Grassland Ecosystems of China: A Synthesis and Resume [1st ed.] 9789811534201, 9789811534218

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Ecosystems of China 2

Linghao Li · Jiquan Chen · Xingguo Han Wenhao Zhang · Changliang Shao

Grassland Ecosystems of China A Synthesis and Resume

Ecosystems of China Volume 2 Series Editors Huajun Tang, Inst of Agri Res & Regnl Planning, Chinese Academy of Agri Sci, Beijing, China Shirong Liu, Resrch Inst of Forest Eco, Env & Protect, Chinese Academy of Forestry, Beijing, China Linghao Li, State Key Lab. of Vege. and Env. Change, Institute of Botany, Beijing, China Jiquan Chen, Center for Global Change & Earth Observa, Michigan State University, East Lansing, MI, USA Ping Xie, Institute of Hydrobiology, Wuhan, China

Due to paucity of content on Chinese ecosystems in the English literature, the extension and incorporation of relevant Chinese research into the international intellectual source has been substantially impeded. The book series Ecosystems of China will generally deal with four categories of Chinese ecosystems, namely the grassland, forest, cropland, and hygroecosystems. Each category accounts for one to several volumes. Each volume will be authored by 4-5 experts from top Chinese institutions, such as Chinese Academy of Sciences, Chinese Academy of Agricultural Sciences, and Chinese Academy of Forestry. The synthesis volumes mainly expound the structural aspects of the ecosystems, whereas the component volumes focus more specifically on the functional mechanisms and ecological processes of relevance. Of special note, the series will build on a total of more than 10,000 research papers and hundreds of specialty books written in Chinese and published in the domestic journals or magazines. Most of these literatures concern the fundamental knowledges as regards the flora, fauna and microorganisms characterizing the structure and biotic composition, as well as physical features and environmental conditions underpinning and driving the functions and survival of various Chinese ecosystems. It is exactly these contents that are crucial in better understanding Chinese biomes as a whole by our foreign colleagues and international institutions. The series can be used as textbooks and research literature for undergraduate and graduate students in ecology, environmental science, natural resource management, agriculture, and other relevant fields. It can be also used as a major reference for researchers studying ecosystems in China, Asia, or globally.

More information about this series at http://www.springer.com/series/16594

Linghao Li • Jiquan Chen • Xingguo Han • Wenhao Zhang • Changliang Shao

Grassland Ecosystems of China A Synthesis and Resume

Linghao Li State Key Laboratory of Vegetation and Environmental Change, Institute of Botany Beijing, China

Jiquan Chen Center for Global Change & Earth Observations, Michigan State University East Lansing, MI, USA

Xingguo Han State Key Laboratory of Vegetation and Environmental Change, Institute of Botany Beijing, China

Wenhao Zhang State Key Laboratory of Vegetation and Environmental Change, Institute of Botany Beijing, China

Changliang Shao Grassland & Remote Sensing Group Chinese Academy of Agricultural Sciences Beijing, China

ISSN 2730-5473 ISSN 2730-5481 (electronic) Ecosystems of China ISBN 978-981-15-3420-1 ISBN 978-981-15-3421-8 (eBook) https://doi.org/10.1007/978-981-15-3421-8 # Springer Nature Singapore Pte Ltd. 2020 This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors, and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, expressed or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. This Springer imprint is published by the registered company Springer Nature Singapore Pte Ltd. The registered company address is: 152 Beach Road, #21-01/04 Gateway East, Singapore 189721, Singapore

Foreword to the Series

The Chinese thought of ecosystem is probably among the earliest in the history of human civilization. The ancient Chinese idea of ecosystem “the unity of heaven, earth, and human” can date back to about 3000 years ago. It is a well-known fact that the earliest written records appeared in China. In Book of Songs, one of the earliest and most famous ancient philosophy works which dates back to 403 BC, it is written to the effect that “Hemiptelea davidii occurs on hills whereas the elm occurs on flat humid sites.” A few centuries later in the Pre-Qin Dynasty, the book Guanzi Diyuan Canto, one of the earliest and most important geographical works, documented the relationship between plants and soils and the vertical distribution of plants on high mountains for the first time. The monograph Dream Brook Sketchbook written by Shen Kuo in as early as the North Song Dynasty (1086–1093) is the first of its kind to have described changes in vegetation distribution with elevation on different slopes and with latitude. This book series with 28 volumes had been regarded by Dr. Joseph Needham as the coordinates of Chinese scientific history, and its French, German, and English editions are currently available worldwide. However, books written in English concerning Chinese ecosystems are extremely lacking, which has substantially impeded the extension and incorporation of relevant Chinese research works into the international intellectual source. Undoubtedly, in varying degrees such a situation has been to the detriment of the integrity and completeness of relevant research and resolution works concerning ecological and environmental issues that have been conducted in a global context, such as Millennium Ecosystem Assessment sponsored by WHO. Relevant world books, such as Ecosystems of the World (D. W. Goodall), International Biological Programme (IBP) Series, and Grasslands of the World (FAO), to name only a few, have involved very little if not nothing of Chinese ecosystems. One has to say that it is indeed a great pity for Chinese researchers on the one hand yet a somewhat loss for the books per se on the other hand, especially in view of the immenseness, uniqueness, and great diversity of Chinese ecosystems. Obviously and understandably, one of the most principal barriers consists in the great difficulty for our foreign colleagues to appreciate the relevant literature written in Chinese. In view of these, we decide to compile the series Ecosystems of China, which generally deals with four categories of Chinese ecosystems, namely the grassland, forest, cropland, and hygroecosystems. Each category accounts for one to several volumes as listed in the inside frontal cover of the current volume. The synthesis volumes mainly expound the structural aspects of the ecosystems, whereas the component volumes focus more specifically on the functional mechanisms and ecological processes of relevance. Of special note, the series will build on a total of more than 10,000 research papers and hundreds of specialty books written in Chinese and published in the domestic journals or magazines, most of which concern the fundamental knowledge as regards the flora, fauna, and microorganisms characterizing the structure and biotic composition, as well as physical features and environmental conditions underpinning and driving the functions and ecosystem services of the various Chinese ecosystems. It is exactly these contents that are crucial in better understanding Chinese biomes as a whole by our foreign colleagues and international institutions.

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Foreword to the Series

I wish that the series can more or less fill the gaps of knowledge and put up with the asymmetry of information in ecological research between China and the outside world. I would like to thank all scientific advisory members, who have contributed priceless insight in the designing and compiling works of the series. Chinese Academy of Agricultural Sciences Beijing, China December 28, 2019

Huajun Tang

Preface

The Chinese grassland (rangeland) accounts for approximately 12.5% of the total area of the world’s grasslands and 41.41% of China’s total land area. It is about three times in size that of the croplands and two times that of the forests of the country. The various grasslands constitute an important part of the natural resources of China. Not only do they provide bases for livestock grazing and animal husbandry production in the broad pastoral regions that determine the livelihood for a population of over 20 million people, but they also play a critical role in maintaining the national environmental and food securities of the whole country. The grasslands and related ecosystems of China may be found in just about all parts of the country—from the cold temperate to the tropics. Generally, five large categories of grasslands are usually classed, i.e., the steppe, desert, meadow, tussock, and wetland. Of these, steppes are most extensive and characteristic, with the alpine steppe endemic to the Qinghai-Tibet Plateau representing the southern extremity of Eurasian steppes. This volume furnishes an overall account of Chinese grassland ecosystems as a whole, with an emphasis on the structural aspects of each of the major grassland ecosystem types, primarily their spatial distribution, geography, climate, soil, flora, fauna, and microflora. In certain detail, it elaborates upon the successional characteristics and managerial practices of certain major ecosystems within each grassland ecosystem type. Of special attention, it puts forward a detailed classification scheme of Chinese grassland ecosystems which are categorized into 11 major ecosystem types. However, it will rely upon the other grassland-related volumes of the series in which functions and processes of certain most principal ecosystem types of the grasslands will be dealt with at length and in depth. As the first author of the volume, I would like to express my heartfelt thanks to those who have helped me so much on all aspects. Dr. Huajun Tang (华俊唐), the editor in Chief of the series and the project leader of “Chinese meadow grasslands: their degradation mechanisms and restoration techniques,” has kindly encouraged me to write this book which appears not rather closely to aim the major target of his project. Dr. Shi Huiqiu (施慧秋) finished all the drawing works of figures. Dr. Yang Liuyi (杨柳依) spent a lot of time in preparing the numerous tables which involve countless Latin names of plants, animals, and microbes that she has surprisingly spelled correctly most of them. Ms. Crank Connor helped so much in English-editing and language polishing. Ms. Cherry Ma and Ms. RaagaiPriya Chandrasekaran, the staff members of Springer, have kindly contacted me many times and solicited the manuscript of the book without minding taking all the trouble. All of them deserve my sincere gratitude. I also would like to thank my career advisors—Profs. Chen Zuozhong (陈佐忠), Chen Lingzhi (陈灵芝), Zou Houyuan (邹厚远), and Lin Peng (林鹏), as well as my friends Drs. Han Xingguo (韩兴国) and Chen Jiquan (陈吉泉), who are among the persons who have enlightened and influenced me so much in the various periods of my research and life experiences.

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To the late professors Li Jitong, Wang Dong, Jia Shenxiu, Li Bo, Zhu Tingcheng, and Zhang Zutong, the most outstanding pioneers and excellent educators in the nation who created the Chinese grassland science. Special thanks are due to Elion Group, especially its chairman of the board, Mr. Wang Wenbiao, for the support to the publication of this volume. Elion long has been committed to the desertification control of the world, and created the internationally-known Kubuqi Desert Mode, which integrates desertification control, ecological protection, industrial development, and poverty alleviation as a whole. The mode has been designated as a global ecological economy demonstration paradigm by the United Nations. The compiling work has been financially supported in turn by the state key research and development program of the Chinese Ministry of Science and technology (2016YFC0500601; 2017YFC0506801), the National Natural Science Foundation of China (No. 41877342), and the Inner Mongolian Pratacultural Research Center, CAS. Beijing, China East Lansing, MI, USA Beijing, China Beijing, China Beijing, China December 26, 2019

Linghao Li Jiquan Chen Xingguo Han Wenhao Zhang Changliang Shao

Series Contributors

Ecosystems of China Editor in Chief: Huajun Tang, Chinese Academy of Agricultural Sciences, Beijing, China Subject Editors: Shirong Liu, Chinese Academy of Forestry, Beijing, China Linghao Li, Institute of Botany, Chinese Academy of Sciences, Beijing, China Jiquan Chen, Michigan State University, East Lansing, MI, U.S.A. Ping Xie, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China Academic Secretaries: Changliang Shao, Chinese Academy of Agricultural Sciences, Beijing, China Xiaoping Xin, Chinese Academy of Agricultural Sciences, Beijing, China Jinling Zhao, Elion Academy of Ecological Technology, Beijing, China Volumes: 1. Overview of Chinese Ecosystems 2. Grassland Ecosystems of China 3. Chinese Steppe Ecosystems 4. Chinese Meadows 5. Chinese Deserts 6. Chinese Wetlands 7. Forest Ecosystems of China 8. Chinese Coniferous Forest Ecosystems 9. Chinese Broadleaved Forest Ecosystems 10. Chinese Scrubs 11. Ecosystems of the Qinghai-Tibet Plateau 12. Agricultural Ecosystems of China 13. Inland Aquatic Ecosystems of China 14. Marine Ecosystems of China 15. Managed Ecosystems of China 16. Ecosystem Research Network of China

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Contents

1

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1 Definitions Concerning Grasslands . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2 Extent of the World’s Grasslands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.3 Classification of the World’s Grasslands . . . . . . . . . . . . . . . . . . . . . . . . 1.4 History of Grassland Ecosystem Research in China . . . . . . . . . . . . . . . . 1.5 Current Advances in Chinese Grassland Ecosystem Studies . . . . . . . . . . 1.6 Treatment of This Volume . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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1 1 3 3 4 7 13 14

2

Overview of Chinese Grassland Ecosystems . . . . . . . . . . . . . . . . . . . . . . . . . 2.1 Broad Distribution and Diverse Grassland Types . . . . . . . . . . . . . . . . . . 2.2 Unique Flora . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3 Highly Adapted Steppe Plants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4 Infertile Soils and Low Productivity . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5 Serious Degradation and Lowered Ecosystem Functions . . . . . . . . . . . . . 2.6 Substantial Shrinkage of Within-Grassland Water Bodies . . . . . . . . . . . . 2.7 Rich Biodiversity of the Wildlife . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.8 Rampant Rodent and Insect Outbreaks . . . . . . . . . . . . . . . . . . . . . . . . . 2.9 Poorly Documented Soil fauna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.10 Little Known Soil Microorganisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.11 Reduced Degradation and Compromising Conservation . . . . . . . . . . . . . 2.12 Delinking of Livestock With Grasslands . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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23 25 26 27 28 29 29 30 33 40 41 42 44 45

3

Natural Conditions Influencing Chinese Grassland Ecosystems . . . . . . . . . . 3.1 Physical Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2 Climates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3 Soils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3.1 Formation of the Soils in China . . . . . . . . . . . . . . . . . . . . . . . 3.3.2 Characteristics of the Soil Resources in China . . . . . . . . . . . . . 3.3.3 Distribution Patterns and Regionalization of Soils in China . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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49 49 52 54 55 60 76 78

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Major Regional Grasslands in China . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1 Tibetan Grasslands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2 Inner Mongolian Grasslands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3 Xinjiang’s Grasslands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.4 Qinghai’s Grasslands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.5 Gansu’s Grasslands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.6 Sichuan’s Grasslands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.7 Yunnan’s Rangelands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.8 Thirteen Nationally Important Regional Grasslands . . . . . . . . . . . . . . . . 4.8.1 Hulun Buir Grasslands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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Contents

4.8.2 4.8.3 4.8.4 4.8.5 4.8.6 4.8.7 4.8.8 4.8.9 4.8.10 4.8.11 4.8.12 4.8.13 References . . .

Horqin Grasslands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Xilin Gol Grasslands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ulan Qab Grasslands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Altay Grasslands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ili Grasslands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lake-Surrounding Grasslands of Qinghai . . . . . . . . . . . . . . . . Gannan Grasslands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Aba (Ngawa) Grasslands . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ganzi Grasslands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Grasslands on the Loess Plateau . . . . . . . . . . . . . . . . . . . . . . . Song-Nen Grasslands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sanjiang Plain Grasslands . . . . . . . . . . . . . . . . . . . . . . . . . . . ...............................................

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105 106 108 108 109 110 111 112 113 114 115 117 118

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Types and Distribution of Chinese Grassland Ecosystems . . . . . . . . . . . . . . 5.1 Methodology and Approaches for Classification . . . . . . . . . . . . . . . . . . . 5.2 Classification of Chinese Grasslands . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.2.1 Vegetation-Based Classification System . . . . . . . . . . . . . . . . . 5.2.2 Rangeland Classification System . . . . . . . . . . . . . . . . . . . . . . 5.2.3 Ren-Hu’s Chart System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.3 Principles and Criteria in This Volume . . . . . . . . . . . . . . . . . . . . . . . . . 5.3.1 Principles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.3.2 Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.4 Classification Scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.4.1 Grassland Ecosystems of China . . . . . . . . . . . . . . . . . . . . . . . 5.5 Distribution of Chinese Grassland Ecosystems . . . . . . . . . . . . . . . . . . . . 5.5.1 Areal Extent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.5.2 Regional Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.5.3 Horizontal Distribution Pattern . . . . . . . . . . . . . . . . . . . . . . . . 5.5.4 Vertical Distribution Pattern . . . . . . . . . . . . . . . . . . . . . . . . . . 5.5.5 Azonal Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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121 121 124 124 124 125 125 125 127 129 129 131 131 131 142 143 145 146

6

Meadow Steppe Ecosystem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.1 Distribution and Geographic Features . . . . . . . . . . . . . . . . . . . . . . . . . . 6.2 Soils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.3 Floristic and Ecological Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . 6.4 Vegetation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.4.1 Stipa baicalensis Formation . . . . . . . . . . . . . . . . . . . . . . . . . . 6.4.2 Leymus chinensis Formation . . . . . . . . . . . . . . . . . . . . . . . . . 6.4.3 Filifolium sibiricum Formation . . . . . . . . . . . . . . . . . . . . . . . . 6.4.4 Cleistogenes polyphylla + Forb Formation . . . . . . . . . . . . . . . 6.5 Root Biomass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.6 Succession . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.6.1 Leymus chinensis Steppe . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.6.2 Stipa baicalensis Steppe . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.7 Fauna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.7.1 Mammals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.7.2 Avifauna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.7.3 Amphibians and Reptiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.7.4 Rodentia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.7.5 Insects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.7.6 Soil fauna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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149 149 151 153 153 153 161 163 164 165 165 165 169 169 169 170 171 174 175 178

Contents

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6.8

Microorganisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.8.1 Microorganisms in the Soil . . . . . . . . . . . . . . . . . . . . . . . . . . 6.8.2 Rhizospheric Microbes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.8.3 Microbes on Litter, Dung and Soil Surface . . . . . . . . . . . . . . . 6.9 Land Use and Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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184 185 186 187 187 189

7

Typical Steppe Ecosystem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.1 Distribution and Physical Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.2 Climate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.3 Soils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4 Floristic and Ecological Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . 7.5 Vegetation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.5.1 Stipa grandis Formation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.5.2 Leymus chinensis and Bunchgrass Mixed Formation . . . . . . . . 7.5.3 S. krylovii Formation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.5.4 Cleistogenes squarrosa Formation . . . . . . . . . . . . . . . . . . . . . 7.5.5 Agropyron cristatum Formation . . . . . . . . . . . . . . . . . . . . . . . 7.5.6 Small Bunchgrass Formation Group . . . . . . . . . . . . . . . . . . . . 7.5.7 Artemisia frigida Formation . . . . . . . . . . . . . . . . . . . . . . . . . . 7.6 Root Biomass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.7 Succession . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.7.1 Stipa krylovii Steppe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.7.2 Artemisia frigida Steppe . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.7.3 Stipa grandis Steppe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.7.4 Leymus chinensis Typical Steppe . . . . . . . . . . . . . . . . . . . . . . 7.8 Fauna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.8.1 Mammals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.8.2 Amphibians and Reptiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.8.3 Avifauna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.8.4 Rodents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.8.5 Insecta . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.8.6 Soil Fauna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.9 Microorganisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.9.1 Abundance of Microorganisms in the Soil . . . . . . . . . . . . . . . . 7.9.2 Biomass in the Soil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.9.3 Rhizospheric Microbes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.10 Utilization and Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

193 194 195 195 196 197 197 201 202 203 204 205 205 207 207 207 212 214 218 219 219 222 223 225 229 233 238 238 241 242 243 245

8

Desert Steppe Ecosystem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.1 Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2 Climate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.3 Soils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.4 Floristic and Ecological Traits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.5 Vegetation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.5.1 Stipa gobica Formation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.5.2 Stipa klemenzii Formation . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.5.3 Stipa glareosa Formation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.5.4 Stipa breviflora Formation . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.5.5 Cleistogenes songorica Formation . . . . . . . . . . . . . . . . . . . . . 8.5.6 Allium polyrhizum Formation . . . . . . . . . . . . . . . . . . . . . . . . . 8.5.7 Dwarf Semishrub Formation Group . . . . . . . . . . . . . . . . . . . . 8.6 Roots . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.7 Succession . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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249 249 251 251 253 254 257 259 260 260 261 262 262 263 264

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8.8

Fauna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.8.1 Mammals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.8.2 Reptiles and Amphibians . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.8.3 Avifauna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.8.4 Rodents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.8.5 Insects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.8.6 Soil Fauna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.9 Microorganisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.10 Land Use and Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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268 268 268 271 271 273 276 278 280 282

9

Alpine Steppe Ecosystem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.1 Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.2 Climate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.3 Soils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.4 Vegetation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.4.1 Flora . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.4.2 Life-Form . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.4.3 Vegetation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.5 Roots . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.6 Fauna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.6.1 Mammals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.6.2 Amphibians and Reptiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.6.3 Avifauna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.6.4 Insecta . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.7 Utilization and Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . .

285 286 287 287 289 289 290 290 297 297 297 301 302 303 304 304

10

Montane Steppe Ecosystem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.1 Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.2 Climate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.3 Soils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.4 Floristic and Ecological Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . 10.5 Vegetation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.5.1 Montane Meadow Steppe . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.5.2 Montane Typical Steppe . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.5.3 Montane Desert Steppe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.6 Roots . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.7 Fauna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.7.1 Mammals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.7.2 Amphibians and Reptiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.7.3 Avifauna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.7.4 Rodents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.7.5 Insecta . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.7.6 Soil Fauna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.8 Microbes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.9 Succession and Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . .

307 308 309 310 312 313 313 317 319 321 321 321 324 324 327 329 331 333 334 335

11

Shrubby Steppe Ecosystem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.1 Climate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2 Soils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.3 Floristic and Ecological Traits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.4 Vegetation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.4.1 Shrubby Meadow Steppe . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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339 340 340 343 343 343

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11.4.2 Shrubby Typical Steppe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Root Biomass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fauna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.6.1 Mammals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.6.2 Amphibians and Reptiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.6.3 Avifauna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.6.4 Rodents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.6.5 Insecta . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.6.6 Soil Fauna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.7 Soil Microbes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.8 Algal Crusts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.9 Succession and Utilization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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346 348 348 348 350 350 350 353 355 355 357 357 362

12

Sandy Grassland Ecosystem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.1 Distribution and Natural Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.2 Soils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.3 Ecological Aspects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.3.1 Life-Form . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.3.2 Ecotype . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.4 Vegetation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.4.1 Sandy Grasslands in the Meadow Steppe Region . . . . . . . . . . . 12.4.2 Sandy Grasslands in the Typical Steppe Region . . . . . . . . . . . 12.4.3 Sandy Grasslands in the Desert Steppe Region . . . . . . . . . . . . 12.5 Fauna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.5.1 Mammals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.5.2 Amphibians and Reptiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.5.3 Avifauna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.5.4 Rodents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.5.5 Insecta . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.5.6 Soil Fauna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.6 Microbes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.6.1 Soil Microorganisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.6.2 Rhizospheric Microorganisms . . . . . . . . . . . . . . . . . . . . . . . . 12.6.3 Microbiotic Crusts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.7 Succession . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.7.1 Hulun Buir Sandy Grassland . . . . . . . . . . . . . . . . . . . . . . . . . 12.7.2 Horqin Sandy Grassland . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.7.3 Hunshan Dak sandland . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.7.4 Mu Us Sandland . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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365 365 366 369 369 371 372 373 373 374 376 376 376 376 379 381 383 386 386 387 390 390 390 391 393 393 398

13

Desert Rangeland Ecosystem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.1 General Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.2 Steppic Deserts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.2.1 Physical Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.2.2 Floristic and Ecological Traits . . . . . . . . . . . . . . . . . . . . . . . . 13.2.3 Vegetation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.3 Typical Deserts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.3.1 Physical Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.3.2 Climates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.3.3 Soils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.3.4 Ecological and Phytogeographic Traits . . . . . . . . . . . . . . . . . . 13.3.5 Vegetation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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401 402 403 403 404 404 409 409 410 411 413 414

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13.4

Alpine Deserts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.4.1 Form. Ceratoides compacta . . . . . . . . . . . . . . . . . . . . . . . . . . 13.4.2 Ajania Alpine Deserts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.4.3 Form. Seriphidium rhodanthum . . . . . . . . . . . . . . . . . . . . . . . 13.4.4 Rhodiola algida var. tangutica Alpine Desert . . . . . . . . . . . . . 13.5 Fauna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.5.1 Mammals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.5.2 Herpetofauna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.5.3 Avifauna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.5.4 Rodents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.5.5 Insects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.5.6 Soil Fauna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.6 Microbes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.6.1 Soil Microbes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.6.2 Rhizospheric Microbes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.6.3 Microbiotic crusts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.7 Succession and Utilization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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428 429 430 430 430 430 430 432 435 436 438 439 442 442 447 447 449 451

14

Meadow Grassland Ecosystem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.1 Typical Meadows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.1.1 Soils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.1.2 Vegetation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.2 Salt Meadows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.2.1 Soils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.2.2 Vegetation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.3 Marshy Meadows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.3.1 Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.3.2 Vegetation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.4 Montane Meadows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.4.1 Low and Medium Montane Meadows . . . . . . . . . . . . . . . . . . . 14.4.2 Subalpine Meadows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.5 Alpine Meadows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.5.1 Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.5.2 Climate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.5.3 Soils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.5.4 Vegetation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.6 Fauna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.6.1 Mammals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.6.2 Herpetofauna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.6.3 Avifauna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.6.4 Rodents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.6.5 Insecta . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.6.6 Soil Fauna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.7 Microbes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.7.1 Typical Meadows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.7.2 Alpine Meadows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.7.3 Marshy Meadows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.8 Succession and Utilization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

455 456 457 459 461 461 462 469 469 469 470 471 473 477 477 478 479 479 487 487 490 491 492 497 498 503 503 504 506 506 511

15

Marsh Grassland Ecosystem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.1 Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.2 Climatic and Hydrologic Characteristics . . . . . . . . . . . . . . . . . . . . . . . . .

515 516 517

Contents

xvii

16

15.3 15.4

Soils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Vegetation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.4.1 Form. Carex muliensis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.4.2 Form. Carex lasiocarpa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.4.3 Form. Carex meyeriana . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.4.4 Form. Carex pseudocuraica . . . . . . . . . . . . . . . . . . . . . . . . . . 15.4.5 Scirpus Formation Group . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.4.6 Carex Plus Deyeuxia Marshes . . . . . . . . . . . . . . . . . . . . . . . . 15.4.7 Carex Plus Juncus effuses Marshes . . . . . . . . . . . . . . . . . . . . . 15.4.8 Form. Phragmites communis . . . . . . . . . . . . . . . . . . . . . . . . . 15.4.9 Zizania caduciflora Marsh . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.4.10 Marshes Dominated by Forbs . . . . . . . . . . . . . . . . . . . . . . . . . 15.4.11 Sphagnum Marshes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.5 Fauna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.5.1 Mammals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.5.2 Herpetofauna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.5.3 Avifauna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.5.4 Insecta . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.5.5 Soil Fauna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.6 Microorganisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.7 Succession and Utilization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . .

518 520 520 521 521 521 521 522 522 522 523 523 524 524 524 525 528 529 531 535 536 542

Tussock and Savanna Ecosystems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.1 Warm Tussocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.1.1 Soils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.1.2 Vegetation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.1.3 Fauna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.1.4 Microorganisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.1.5 Succession and Utilization . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.2 Hot Tussocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.2.1 Soils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.2.2 Vegetation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.2.3 Fauna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.2.4 Microbes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.2.5 Succession and Utilization . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.3 Savannas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.3.1 Form. Heteropogon contortus Plus Pinus yunnanensis . . . . . . . 16.3.2 Form. Bombax malabarica . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.3.3 Form. Flacourtia indica Plus Streblus asper . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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545 545 546 547 548 555 557 559 560 562 565 572 575 576 579 579 580 580

1

Introduction

Abstract

This chapter discusses definitions concerning grasslands of the world that have been put forward by different authors, adopted by different countries or regions, or employed in different research fields of the world. It briefly elaborates upon the extent of the world’s grasslands and their major classification schemes. It introduces in greater detail the history of and reviews at length the current advances in Chinese grassland ecosystem studies.

Together, they constitute a land-use complex of natural resources: the rangeland. Only by doing the above can grasslands equate to rangelands in meaning. Thus, we divide grasslands into two such divisions (typical vs. atypical) in this volume, which sets the basic principle for designing the structure of the book. This volume concerns mainly the natural grasslands in China, with emphasis placed on the zonal grasslands occurring in the temperate regions of north China in particular. In addition, it covers three themes in respect to grasslands, i.e., vegetation, land resources, and ecosystem, respectively.

Keywords

Grassland · Rangeland · Biome · Vegetation · Ecosystem

1.1 Formal statements concerning ecosystems began to appear in the literature in the late 1800s. The term “ecosystem” was first put forward in 1935 by the British ecologist Tansley (1935). Concurrent counterpart concepts during the same period include “biocoenosis” (by German ecologists) and “geobiocoenosis” (by Russian ecologists). However, it is E.P. Odum who established a general ecosystem theory in the mid-twentieth century. An ecosystem or ecological system was defined by Dr. Odum as “any unit that includes all the organisms in a given area that interact with the physical environment so that energy flow leads to clearly defined biotic structures and matter cycling between living and nonliving components” (Odum and Barrett 2005). In Chinese literature, there are many references to two categories of grasslands, namely the typical grassland and the atypical grassland. Typical grasslands, also defined as true grasslands, are those which are dominated by herbaceous plants, especially grasses. Atypical grasslands, in contrast, denote those dominated by grass-like herbs such as sedges and broad-leaf forbs, semishrubs, and shrubs that can be utilized for raising livestock, either by grazing or by mowing.

# Springer Nature Singapore Pte Ltd. 2020 L. Li et al., Grassland Ecosystems of China, Ecosystems of China 2, https://doi.org/10.1007/978-981-15-3421-8_1

Definitions Concerning Grasslands

It is not easy to give an entirely useful, strict, all-inclusive yet generally accepted definition of “grassland.” There exists a series of terms describing purpose-oriented or specifically focused grasslands in question in voluminous ecological, agricultural, rangeland management, and land-use literature across the world. Of these, three categories of definitions are most commonly associated with grasslands, wherein grasslands are defined from vegetation, land-use, and ecosystem perspectives. In the early days, floristically based definitions prevailed, which defined grasslands simply as “a habitat dominated by grasses” (Gibson 2009). Milner and Hughes (1968) further considered a grassland physiognomically or structurally as “a plant community with a low-growing plant cover of non-woody species.” Risser’s definition is much more comprehensive, the main points of which include “the dominance of herbs (grasses) of the family Poaceae (formerly Gramineae or true grasses), an infrequent occurrence of woody species, and a generally arid climate” (Risser 1988). In recent decades, more considerations of importance have been incorporated into the understanding of the grassland,

1

2

inclusive of such characters as soil regime, fire frequency, and grazing history as well as soil fauna and microbes (White et al. 2000). The Oxford Dictionary of Plant Sciences gives a succinct definition that a grassland occurs where there is sufficient moisture for grass growth, but where environmental conditions, both climatic and anthropogenic, prevent tree growth. Its occurrence, therefore, correlates with a rainfall intensity between those of the desert and the forest, and is extended by grazing and/or fire to form a plagio-climax in many areas that were previously forested (Gibson 2009). For a considerable number of grassland researchers worldwide, grassland is generally synonymous with rangeland. Therefore, a strict distinction between the grassland and the rangeland is necessary. According to the yearbook “World Resources 1994–1995,” the term “rangeland” refers to land on which native vegetation is dominated by grasses, forbs, and shrubs, and the plants are well suited as forage for wildlife and livestock (World Resources Institute 1994). In effect, rangeland is a more land-use type-based concept, and includes various terrestrial ecosystems in addition to grassland that potentially can be or have been mainly used for livestock grazing, with grassland being its major component. For instance, in the World Resources Institute’s series of statistical reports (1994–1995), North American rangelands were classified into categories of natural grassland, shrubland, desert, woodland, alpine meadow, coastal marsh, wet meadow, bald mountains, and tundra as well as forestderived pastures and meadows. UNESCO provides a relatively clear distinction between the grassland and the rangeland, stating that rangeland is, in a narrow sense, “grassland,” whereas grassland in the wider sense equates rangeland. Therein, grassland is defined as “land covered primarily by herbaceous plants with less than 10% of the tree and shrub cover,” whereas rangeland is defined by allowing this percentage to rise to 10%–40% (Suttie et al. 2005). Definitions of terrestrial ecosystems that include the associated term “range” have been variously manifold, many with specific local or legal connotations. For example, the second expert meeting on harmonizing forest-related definitions for use by various stakeholders (Suttie et al. 2005) afforded eleven pages to elaborate upon them. From an ecosystem perspective, grasslands are defined mainly with consideration to climate, soil, geography, vegetation, and human disturbances. In “Ecosystems of the World 8B,” emphasis is firstly given to zonality and continuity: grassland should be capable of maintaining its biotic composition and structure in zonal conditions such as zonal climates, soils, and geographical features (Coupland 1993); the vegetation is herbaceous in nature, with grasses being most dominant. The book stresses that natural grasslands are dominated by perennial grasses and sedges (collectively referred to as graminoids) in pristine conditions, whereas annuals will dominate grasslands wherein the climax

1

Introduction

vegetation has been disturbed. Non-graminoid herbs (broadleaved forbs) constitute a varying proportion of the vegetal cover, and mosses, club-mosses, and lichens occur occasionally below the canopy at specific biotopes, while half-shrubs and dwarf shrubs are permitted to occur to a limited extent (Coupland 1993). This definition of “grassland” is effectively limited to vegetation- or is a botanically oriented one, although it takes into account human impacts in the grouping of the higher taxa. It should be noted that “grassland ecosystem” should be defined with the inclusion of many more considerations and aspects in addition to those elaborated above, such as mammals, soil fauna, microorganisms, biogeochemical characteristics, and azonal elements, if these factors are forceful enough in controlling the functions and processes of the ecosystem in question. An ecosystem may be considered as grassland when the cover of grasses is generally continuous and exceeds 50% of the total ground area. Thus, savannas have long been recognized as grasslands, because they are ecologically homogenous with scattered woody plants interspersed in the grassland communities, and generally occur in the relatively dry and extremely nutrient-poor areas of the world. Savanna is determined primarily by soils rather than by climate and thus is regarded as a pedobiome (Walter 1985). In this sense, the Hunshan Dak sandland of Inner Mongolia can be justifiably designated as a temperate savanna, although many Chinese ecologists are reluctant to accept this view point. Artificial grasslands refer to those that are established by the sowing of domesticated forage species, with the grass species of Poa, Agropyron, and rye as well as legumes such as alfalfa and clover being the most prominently seeded throughout the world. These species occupy mostly abandoned or damaged farmlands. By contrast, seminatural grasslands were once originally natural grasslands that have become degenerated and were later improved by reseeding, fertilization, or harrowing. They also occur in forest zones where forest stands were thoroughly cleared or seriously damaged by grazing, burning, and other human or natural disturbances. In such cases, annual herbs, followed by perennial grasses, become established and remain constant at these sites until the factors arresting succession to forest terminate. Different continents have their regional or local terms for grasslands. For example, grasslands in North America are usually referred to as prairie, while in the hot climate regions of South America they are referred to as campos (in Uruguay and southern Brazil) and pampas (in Argentina). In the inner part of the Eurasian continent, steppe is synonymous with natural grassland, whereas savanna (savannah) indicates the tropical grasslands of Africa (Coupland 1993). In addition, the terms meadow and pasture frequently appearing in the literature refer to natural or managed (man-made) grasslands for mowing and grazing, respectively (Gibson 2009).

1.3 Classification of the World’s Grasslands

1.2

3

Extent of the World’s Grasslands

Rangeland constitutes the largest zonobiome in the world (Gibson 2009). Its total area is estimated at 52.5 million km2, covering roughly 40.3% of the world’s total land area (excluding Antarctica, about 130.4 million km2 in area) (World Resources Institute 1994; White et al. 2000; cf. Gibson 2009). Of the total rangeland of the world, grasslands account for 22.1% of Earth’s land area, which comprise the savanna (13.8%, 17.9  106 km2) and the nonwoody grassland (8.3%, 10.7  106 km2). This product is derived by excluding open and closed shrublands (16.5  106 km2) and tundra (7.4  106 km2) from the total amount of rangeland, which account for 12.7% and 5.7% of the world’s total land extent, respectively. Various other estimates have been made concerning the total area of the world’s rangelands, which range from 41 to 56 million square kilometers. This large difference arose mainly from different definitions by different institutions as to what extent shrublands or deserts should be included. The World Resources Institute’s estimates concerning grasslands are largely comparable to those derived from the IBP-grassland biome studies, which gave a relevant estimate that 23% of the world’s total land area was held by grasslands (primarily typical or nonwoody grassland and savanna), including both natural and managed grasslands (Coupland 1979). Estimated proportions of the overall grassland area in the global land area during different periods are 18.4% (15.0  106 km2 for savannas and 9.0  106 km2 for temperate grasslands) by Whittaker and Likens (1975) and Schlesinger (1977), 26.8%(22.5.0  106 km2 for savannas and 12.5  106 km2 for temperate grasslands) by Ajtay et al. (1979), and 30.4%(24.6  106 km2 for savannas and 15.1  106 km2 for temperate grasslands) by Houghton and Skole (1990), respectively, which to a certain extent reflect the considerable temporal variations in grassland area. On the other hand, this inconsistency is largely due to the fact that, while some parts of the grassland are becoming deserts, forests are being felled elsewhere.

World Resources Institute (1994) had estimated the total area of the rangelands in China at 3.92 million km2, the third largest in the world next only to Australia and Russia (Table 1.1). This estimate is highly comparable to that made by Chinese researchers, which totaled 3.93 million km2 (Liao and Jia 1996).

1.3

Classification of the World’s Grasslands

Various approaches have been employed to classify the world’s grasslands. Coupland (1979) noted that the botanically based approach is justifiable only at a local or regional scale, whereas it is generally inadequate and infeasible when used for intercontinental classifications of vegetation or ecosystems, mainly because of the discontinuity in the distribution of plant species. Thus, it is necessary in such cases to take into account the similarities in climate, soil, and other biotic factors as well as the utilization patterns in grouping analogous object taxa of different regions. In IBP-Grassland Biome Studies, the term “grassland” refers to ecosystems in which vegetation is predominantly composed of herbaceous species, whereas deserts, shrublands, and woodlands were excluded because their herbaceous floristic elements play a secondary role. Certain communities of tundra and meadow were recognized in their treatment as grasslands as they were in many aspects similar enough to grassland, especially at ecotones and boundary areas where they were alternately distributed with grasslands. Accordingly, world grassland ecosystems were classified into six top categories, namely temperate natural grassland, temperate seminatural pasture (deforested areas under forest climates), temperate seminatural meadow, tropical grassland, arable grassland (improved by minimal tilling, fertilization, oversowing, chemical suppression, etc. alone or collectively), and cropland (for growing forage or herbage crops) (Coupland 1979). In contrast, in Ecosystems of the World 8, world grasslands were divided into two parts, i.e., the western and the eastern hemispheric grasslands. Lower levels were

Table 1.1 Rangeland areas of major continents and countries in the world (million km2)a Region Asia Europe M East -N. Africa Sub-Saharan Africa North America C. America, Caribbean South America Oceania World a

Rangeland type Savanna Shrubland 0.90 3.76 1.83 0.49 0.17 2.11 10.33 2.35 0.32 2.02 0.30 0.44 1.57 1.40 2.45 3.91 17.87 16.48 b

Note: Adapted from Gibson (2009); Rangeland area

Grassland 4.03 0.70 0.57 1.79 1.22 0.30 1.63 0.50 10.74

Tundra 0.21 3.93 0.02 3.02 0.26 7.44

Total 8.89 6.96 2.87 14.46 6.58 1.05 4.87 6.86 52.23

Country Australia Russia China USA Canada Kazakhstan Brazil Argentina Mongolia

Areab 6.59 6.26 3.92 3.38 3.17 1.67 1.53 1.46 1.31

4

1

determined according to the major continents in which they occurred, whereby five categories were recognized, i.e., the grasslands of North America, the grasslands of South America, the grasslands of Eurasia, the grasslands of Africa, and the grasslands of Oceania (Coupland 1993). In the FAO-sponsored study undertaken by the Grassland and Pasture Crops Group, emphasis was placed on the extensive rangelands (grazing lands) of the world, including not only natural grasslands but also seminatural (improved or managed via oversowing, surface scarification and fertilization) grasslands deriving from cleared woody vegetation, as well as man-made grasslands. In the composition of its official book titled “Grasslands of the World,” nine major rangeland regions, including 3 subcontinents (South African grasslands, North American grasslands, South American campos), 3 countries (Mongolian rangelands, Russian steppes, Australian grasslands), and 3 regions (east African rangelands, Patagonian grasslands, Tibetan steppes), were recognized (Suttie et al. 2005). In the series “Ecosystems of the World,” the world’s grasslands were divided into three categories: natural grasslands, managed grasslands, and tropical savannas. Within the natural grasslands, a continent-based approach was adopted wherein they were further distinguished into five subcategories, including the grasslands of North America, the grasslands of South America, the grasslands of Europe and Asia, the grasslands of Africa, and the grasslands of Oceania (Coupland 1992).

1.4

History of Grassland Ecosystem Research in China

Ecosystem research started with vegetation and soil surveys in China. Early vegetation studies were represented by the following pioneering research works conducted by Chien (1927, 1932) on the vegetation and flora of Mount Huangshan, by Li JT on the forest vegetation of Shi-Shan and Hsiao-Wutai-Shan (Yang 1937; cf. Wu et al. 1980) and the vegetation of Yunnan (Wang 1939, qtd. from Wu et al. 1980), and by Liu (1934) on the phytogeographical characteristics of northern and western China. The late Dr. Hou HY, of the Institute of Botany, Chinese Academy of Sciences (IBCAS), was the founding father of contemporary vegetation ecology in China and one of the earliest phytoecologists. He carried out in-depth studies on the relationship between vegetation and soils (Wu et al. 1980) and published his famous monograph “Indicator Plants” (Hou 1954) based on his many years of field investigations in Sichuan and Guizhou (Hou 1944). Based on a field survey on the Xisha Archipelago of Hainan, Zhang (1948) published his scientific report entitled “Vegetation of the Paracel (Leizhou) Islands.” Subsequently, several local or regional

Introduction

vegetation surveys were carried out, of which those conducted on Mount Mangshan of Hunan and in western Sichuan (Zheng 1949) and in the Nanjing area (Chu et al. 1952), Gansu and eastern Tibet (Teng 1947, 1948a) were most representative. At the same time, Teng (1948b) initiated research on vegetation geography and regionalization in China. These early works mostly involved grassland environments, vegetation and soils to some extent, although some were primarily forest-oriented. Large-scale and systematic baseline surveys of grasslands were conducted successively by different institutions during the three decades from the 1950s to the 1970s, of which those organized by the Chinese Academy of Sciences were the most extensive, systematic, and fruitful. These involved flora, vegetation, soils, climate, geographical characteristics, types, and distributions of important regional grasslands in the country, based upon which a number of important relevant books and reports were published. The most influential books are briefly introduced in the time sequence of publishing as follows. The work “Vegetation in China” (Hou 1960) is probably the earliest vegetation book in China. It summarized all the knowledge concerning various major vegetation types occurring in China based on all the data and references available at that time and especially those achieved in the 1950s. It introduced for the first time the concepts, contents, and methodology in vegetation and geobiocoenosis research, and generally described the natural conditions, especially soils and climates influencing the distribution patterns, succession and ecological relations of different types of Chinese vegetation, with particular emphasis on the vegetation classification and regionalization in China. In addition, the book put forward for the first time the research tasks and methods employed in vegetation mapping, highly stressing the importance of vegetation mapping in vegetation studies. This book provided the guidelines and framework for vegetation studies in the country for the ensuing decades. Of special significance is the book’s establishment of a classification scheme of the four major subtypes of temperate grassland vegetation in China, namely, meadow steppe, typical steppe, desert steppe, and shrubby steppe. “Vegetation of China” (VOC) is undoubtedly the most systematic, comprehensive, and authoritative vegetation book in China, and involves nearly all important aspects of Chinese vegetation such as the natural environments, floras, vegetation types, distributions and regionalization, succession, as well as utilization and protection (Wu et al. 1980). It was a collective reflection of the knowledge level, field and laboratory data, publications and historical literature of the vegetation ecology studies of contemporary China; its compilation involved hundreds of vegetation researchers and built on some 773 references. The data and materials were derived from all previous large-scale field surveys, including

1.4 History of Grassland Ecosystem Research in China

the field survey on soil and water conservation of the middle reaches of the Yellow River (1953–1955), the comprehensive survey on the natural resources of the Heilong River drainage area (1956–1959), the field investigation of vegetation in the Xinjiang region (1956–1959), the investigation on the biological resources of southern China (1958–1961), the integrative field survey on the tropical biological resources of southwest China (1957–1961), the integrative survey on the natural conditions and resources, geographical features, and vegetation of the Gansu-Qinghai region (1958–1960), the comprehensive field survey of the eleven important deserts and sandlands in northwest China and Inner Mongolia (1959–1965), the field survey on the water resources, soils, vegetation, forestry, geology, and physiognomy of northwestern Yunnan, western Sichuan, and southern ShaanxiGansu region (1960–1963), the comprehensive field investigation of natural conditions, grasslands, agriculture, animal husbandry, water resources, and others in Inner Mongolia and Ningxia (1961–1965), the comprehensive baseline investigations of the Tibet region (1951–1976) on flora, fauna, vegetation, geology, landform, mountains, and rivers, and the comprehensive survey of the soils and land resources of northeast China with emphasis on those of the Greater Hinggan mountains, the Sanjiang Plain, the Song-Nen Plain, and the Hulun Buir grassland (1973–1977). It should be noted that the vast majority of these large-scale surveys and investigations were organized by the Chinese Academy of Sciences. As important successive supplementary documents, the “Vegetation Atlas of the People’s Republic of China (1:one million)” along with two volumes of the descriptive book were published in 2007 (Zhang et al. 2007a). Steppes had been fully elaborated in VOC, and many findings concerning their major types, distributions, and successive relations were revealed therein for the first time. For instance, the meadow steppe had been previously regarded as making up the entire northeast steppe region. However, according to field investigations it was found that a considerable portion (the southwestern portion) of the Northeast Plains was occupied by the typical steppe. The Stipa grandis typical steppe had long been ignored in the past when it came to the typical steppe, whereas it was later found to be more widely and predominantly distributed than the Stipa krylovii steppe, which was previously considered the most typical of the typical steppe. It was made clear for the first time that the majority of the middle Qinghai-Tibet Plateau’s vegetation belongs to the alpine meadow steppe and the alpine typical steppe, rather than meadows or deserts. In addition, the shrubby and montane steppes were categorized into non-original steppe subtypes. Most importantly, the major steppe subtypes and their formations, species compositions, community traits, structural characteristics, and ecogeographical distribution patterns along with the formation-level biomass and NPP parameters were basically figured out.

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In addition to VOC, several other important regional grassland vegetation books resulted from the abovementioned field surveys and investigations. These include: “Vegetation of Inner Mongolia” (IMNCST- Inner Mongolia-Ningxia Comprehensive Survey Team of CAS 1985), “Vegetation of Xinjiang and Its Utilization” (XJCST- Xinjiang Comprehensive Survey Team of CAS 1978), “Vegetation of Tibet” (QTPCST- the Qinghai-Tibet Plateau Comprehensive Survey Team of CAS 1988), “Grasslands of Tibet” (QTPCST- the Qinghai-Tibet Plateau Comprehensive Survey Team of CAS 1992), and “Vegetation of Qinghai” (Zhou et al. 1987). In addition, a number of specific books on local grassland resources and their utilizations were published at the same time, including “Natural Pasture Resources in Xinjiang Region” (XJCSTXinjiang Comprehensive Survey Team of CAS 1964a), “Natural Grassland Resources in Some Regions of the Western and Northern China” (XJCST- Xinjiang Comprehensive Survey Team of CAS 1964b), “Natural Grasslands of Pan-Inner Mongolia region” (IMNCST- Inner Mongolia-Ningxia Comprehensive Survey Team of CAS 1980), and “Atlas of Grassland Resources in China (1:1 million)” (Natural Resources Comprehensive Survey Commission 1995). Soil research developed in a roughly parallel manner with that on vegetation in China. The most foundational works of research included the earliest descriptions of soils in China by Shaw (1930), Suo Po (James Thorp 1934), and Li (1934), more accurate elucidations of soil types and distributions by Li (1936a, b), and classifications of soils by Hou (1941). The “Outline Map of Chinese Soils (1:15,000,000)” by Suo is probably the earliest one of its kind in China (Li 1934). Large-scale regional soil surveys had been consecutively conducted from the 1950s to the 1980s, including those carried out in the rubber tree-appropriate areas of south China, the middle and lower reaches of the Yellow River, the Yangtze River valleys, the Heilongjiang River catchment of the northeast, the North China Plains, Xinjiang, Tibet, Gansu, and Pan-Inner Mongolia (Zhang et al. 2008). By drawing on the resultant data, figures, pictures, and other materials, a number of important grassland-relevant soil books were published, including “Soil Geography of Xinjiang” (Wen 1965), “Soils of Tibet” (QTPCST-the Qinghai-Tibet Plateau Comprehensive Survey Team of CAS 1985), and “Soil Geography of the Pan-Inner Mongolia” (IMNCST 1978). “Soils of China” (first edition by the Institute of Soil Science, CAS 1978, and second edition by Xiong and Li 1987) was an agglomeration of the achievements arising from the aforementioned field surveys. The book unravels the types, distributions, geneses, and controls of major soils in China. It elucidates the general physical and chemical properties of the soils, the characteristics of nutrient availability and cycling, and the relevant knowledge on soil organisms and their ecological functions, whereby it further explores the improvement

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approaches and management strategies of China’s soil resources. The book delivered a complete and systematic introduction to contemporary soil studies in China and remains informative even in the light of current standards. Highly important and specific, it is rather natural ecosystemand resources-oriented and covers many topics that are critically important to ecosystem studies, and involves almost all of the important natural ecosystem types in China, such as forests, grasslands, meadows, and deserts. Due to the special importance of soils in agriculture, the nationwide soil census was conducted twice. The first soil census was conducted during 1958–1960 with an emphasis on farmlands; the second was carried out from 1979 to 1985 and involved not only croplands but also various natural ecosystems. The synthetic results were summarized in the monograph “Soils in China” (Xi 1998), concerning the formation, classification, and distribution of soils in China, the major soil types and their characteristics, soil fertility, and the exploitation, utilization, and improvement of soil resources and their regional development strategies. In addition to this synthesis book, the 6-volume series of Chinese soil species and most of the provincial soil books were successively published. Grassland vegetation surveys also have a long and winding history. Early grassland vegetation-specific studies were characterized by the following pioneering research works, including those conducted by: Li JT on the distribution of steppes and deserts in China (Li 1930, qtd. From Liao and Jia 1996), Wang (1953) on the vegetation types and forage grasses of the Xilingol steppe, Jia (1953) on the plants and soils of Tibetan grasslands, Ren (1957) on Gansu grasslands, Zhu (1958) on steppe types and distributions in northeast China, Chen (1958, 1964a, b) on the vegetation functions of grasslands on the Loess Plateau and on the division line between the typical and the desert subregions, Zhang (1960) on the types and productivity of the Hulun Buir grassland, Liu (1960) on the vegetation characteristics of the Inner Mongolian steppe, Li (1962) on the major types and ecogeographical patterns of the zonal vegetation in Inner Mongolia, Wang (1963) on the montane steppes of the Tianshan Mountains, Jiang (1964) on the alpine steppe of western Sichuan, Xü et al. (1993) on the montane steppes of Xinjiang, Xü (1963) on the tussock grasslands of south China, and finally Liu (1965) on the steppe in Bashang area of Hebei Province. Grassland ecosystem studies in this period were mainly concerned with the classification, distribution, and ecogeographical relations of Chinese grasslands at regional or zonal scales. The first baseline survey of grassland resources at the country scale, initiated in 1979 and lasting until 1987, was the most extensive, accurate, and finely scaled of its kind in China. Under the coordination of the Chinese Ministry of Agriculture, the task was undertaken by the provincial

1

Introduction

division of grassland management of each province, with technicians of the grassland management stations at the county level responsible for field investigations and data collection. On average, a sampling site was set up for a controlled area of 50–100 km2 to measure species composition, community indexes, standing crop biomass, and landuse status. A total of at least 30 thousand sampling sites were investigated. The achievements include: a series of maps of grassland resources at county (1:100,000), regional (1:200,000), provincial (1:500,000), and national (1:1million) levels, respectively, statistical databases and materials on the type, area, forage yield, and stocking rate at various scales, a technical report at the provincial level for each major grassland province, and a synthesis report on grassland resources in the country as a whole (Liao and Jia 1996). By drawing on the data and materials produced from the survey, a number of relevant books have been published, of which “Grassland Resources and their Exploitation and Utilization of Eleven Important Grassland-Animal Husbandry Regions in China” (Zhang and Liu 1992) and “Rangeland Resources of China” (RRC) (Liao and Jia 1996) are most comprehensive and systematic. The classification system and the regionalization scheme have become widely accepted in the studies of grassland resources and management in China, and data on the area and distribution of grasslands at the type, subtype, and group levels as well as at areal, regional, and zonal scales are reliable and authoritative. In a strict sense, ecological research on China’s grasslands commenced in earnest in the late 1950s, characterized by studies that focused mainly on their structural aspects, plant biomass, and productivity at the community level, and a few studies concerned with plant and soil or water relations. The most representative works were those conducted by: Chen (1958) on the vegetation and its role in soil-water conservation in the Ziwu Ridge area, Fang and Wen (1958) on the distribution and environmental characteristics of Stipa species in middle and western Inner Mongolia, Wang and Chen (1959) on grassland vegetation in the northern section of the Zhangbei-Huade-Jining-Erenhot line, He (1963) on Guangdong tropical savanna, Zhu and Zhao (1963) on the vegetation complex in the northeast grassland, Liu (1963) on Stipa grasslands in Inner Mongolia, Lang et al. (1964) on marsh vegetation of the western Sichuan plateau, Huang et al. (1963) on the canopy structure characteristics of perennial grasses, Hu (1963) on the Haloxylon ammodendron desert in northwest China, Zhang (1963) on the basic characteristics and zonal significance of the alpine steppe on the southeastern Qiangtang plateau, Huang and Lin (1964) on the growth rhythm of desert plants in relation to ecological factors, Jia (1964) on the principles for classifying Chinese grasslands and their major types, Wang (1964) on the distribution of halophilous plant communities in relation to surface soil moisture and groundwater, Li (1964) on water relations of

1.5 Current Advances in Chinese Grassland Ecosystem Studies

Leymus chinensis and bunchgrass communities, Kong and Liu (1964) on the contents of chemical elements in plants of different ecotypes in the sandy grassland, Jiang et al. (1965) on pasture types and their economic evaluation in the southeastern Yushu area of Qinghai Province, and Li and Xiao (1965) on the succession of a Leymus chinensis steppe. Ecological research on mammals in Chinese grassland ecosystems was relatively poorly documented during this same period, as characterized by faunal investigations and very simple zoogeographic studies. According to Zhang and Lin (1981), some 207 papers or abstracts had been published on the topic as of 1981 in China, among which 77 were on general faunal investigations, 49 were specifically on rodents, 48 were on investigations of “economically important” mammals, and 33 were on zoogeographical characteristics. Of these, only 19 were conducted in the grassland regions of Xinjiang, Tibet, and Inner Mongolia, with 11 on regional or local faunas, 2 on rodents, and 6 on others. The research by Sun et al., on rodents in the Linhe forest was one of the earliest works in a real ecological sense (Zhang and Lin 1981). Ecological research on insects was rarely documented; only 4 grassland-relevant articles had been retrieved that were published before 1980. Zhang (1955) investigated the distribution, habitat selection, and life cycle of Locusta migratoria in the Xinjiang desert and grassland; Ma (1958) investigated the population dynamics of Locusta migratoria manilensis in China; Chen led the entomological expedition to Tibet from 1960 to 1961 during which he focused on the ecogeographical aspects of the Chrysomelidae insects in the order Coleoptera (Chen 1963) and the Acrididae insects of Orthoptera (Chen 1964a, b); Wang (1966) investigated the population dynamics of a beetle species injurious to grasslands on the Qinghai plateau. Studies on the soil fauna of some important terrestrial ecosystems have been fully summarized by Yin (2000) in her famous writings “Soil animals of China,” which reviewed in detail the relevant advances in the ecogeographical studies of the soil fauna in China at that time. Research on the functions of microorganisms in grassland ecosystems was almost entirely lacking before 1980. However, enlightened by the outcomes of the IBP program, ecological studies on the faunal taxa and microbes in Chinese grassland ecosystems boomed during the 1980s, with those concerning the temporal and spatial patterns of biomass, the identification of important functional groups, and the characteristics in nutrient cycling of the major microbial and faunal groups being particularly numerous. Readers are referred to the series “Research on Grassland Ecosystem” (Vol. 1–5) edited by the Inner Mongolian Grassland Ecosystem Research Station on the typical steppe and the series “Alpine Meadow Ecosystem” (Vol. 1–6) edited by the Haibei Alpine Meadow Ecosystem Research Station.

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Stationary field studies of Chinese grassland ecosystems were initiated by Xia and Zhou on the alpine meadow grassland (Xia 1982), by Jiang (1988), Li et al. (1988a, b), and Chen (1988) on the typical steppe, by Zhang on the sandy grassland (1990), by Zou (1986) on the Loess Plateau shrubby steppe, by Ren and Hu on the mountain grassland (Hu et al. 1994), by Zhu and Li on the Song-Nen Plain meadow grassland, by Li and Tang on the Hulun Buir meadow steppe, by Han and Li (2012) on the agro-pastoral ecotone region, and by Zhang and Li on the desert steppe (Wei et al. 2013b). Important journals concerning grassland ecosystem studies comprise the “Chinese Journal of Plant Ecology (1958-),” the “Chinese Journal of Grasslands (1979),” “Acta Ecologica Sinica (1981-),” the “Chinese Journal of Ecology (1982-),” the “Chinese Journal of Applied Ecology (1990-),” “Acta Prataculturae Sinica (1990),” “Acta Agrestia Sinica (1991-),” and “Pratacultural Science (1984-).”

1.5

Current Advances in Chinese Grassland Ecosystem Studies

Initial field surveys of grassland vegetation and plant species in the nation date back to the end of the nineteenth century, whereas large-scale, systematic explorations and investigations of vegetation, soils, climates, and geography of the principal grassland regions were conducted during the 1950s–1980s. However, it was not until the mid-1980s that comprehensive studies of the community dynamics, ecosystem functions, and biogeochemical processes at several pilot steppe sites, studies of various regional steppes as a whole that integrated multi-scale and multidisciplinary approaches, and the multifactor manipulative experiments were initiated (Kang et al. 2007). The formal beginning of grassland ecosystem studies in China was generally marked by the establishment and operation of two of the best-known grassland ecosystem research stations affiliated with the Chinese Academy of Sciences. The Inner Mongolian Grassland Ecosystem Research Station (IMGERS) of the Institute of Botany, CAS, was set up in 1979, and ever since has been conducting a series of studies covering nearly all aspects of the Stipa spp. and Leymus chinensis mixed typical steppe ecosystems (NRC 1992). The station runs two permanent plots in situ for observations of the long-term changes in vegetation and environmental factors; its treatment plots of plant species removal, grazing, and burning are unique and open to the public. The second, the Northern Qinghai Alpine Grassland Ecosystem Research Station (the Haibei station for short), was established in 1976 and belongs to the Northwest Institute of Plateau Biology of CAS, which aims specifically at the alpine steppe ecosystem,

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with its studies focused most characteristically on the biological responses of the biota to climate change. Following the establishment of these two stations, a number of other grassland ecosystem research stations have come into being. The Hulun Buir Meadow Steppe Ecosystem Research Station of the Chinese Academy of Agricultural Sciences (CAAS) (1997-) focuses mainly on the impacts of utilization and management on the meadow steppe ecosystem of the eastern Inner Mongolia grassland. It runs a 5-class grazing intensity experimental plot with cattle ranging, which is probably among the most accurately controlled and groundhomogenous field plots in the world. The Duolun Restoration Ecology Experimentation and Demonstration Station (2000-) of IBCAS is primarily concerned with degraded ecosystems of the agro-pastoral ecotone grassland, and its multifactor manipulative experiment is internationally known and highly comprehensive. The Siziwang Desert Steppe Research Station (2001-) affiliated with the Inner Mongolian Academy of Agricultural and Animal Husbandry Sciences is located in the interface area between the Loess Plateau and the Mongolian Plateau; its research is concentrated on the desertification process of grassland ecosystems as impacted by overgrazing. The Ordos Sandland Ecological Research Station (1990-) of IBCAS is located at the hinterland of the Mu Us desert. It has long been devoted to the study of the optimal paradigm for ecosystem production and ecological services of sandland ecosystems. At present, 20 more field research stations of grassland ecosystems belonging to various institutions of CAS, the Ministry of Agriculture, and various universities are in operation, and involve nearly all chief grassland types. The Chinese Ecosystem Research Network (CERN) created in 1988 by CAS and the National Science and Technology Infrastructure Project initiated in 2006 jointly coordinate the concerted operations of some of the key research stations (Han et al. 2019). The structures, functions, and processes of the Inner Mongolian temperate grassland ecosystems have been studied most extensively, of which the studies on the typical steppe ecosystem are most systematic, intensive, and comprehensive (Kang et al. 2007). In-depth studies regarding Stipa grandis and Leymus chinensis mixed typical steppe ecosystems have been conducted mostly at the Xilingol station (IMGERS). Han XG and his colleagues and students have been concentrating on studies regarding nitrogen biogeochemistry (Wang et al. 2006; Cheng et al. 2009; Giese et al. 2013), greenhouse gas dynamics (Chen et al. 2010; Wang et al. 2008; Wolf et al. 2010), soil microbes (Wei et al. 2013a; Zhang et al. 2014b, 2015, 2016a), plant species dynamics (Zhang et al. 2014c, 2016b) and stoichiometric ecology (Yu et al. 2010; Zhang et al. 2011c; Yu et al. 2015). Bai YF and his associates focus on revealing temporal-spatial patterns and controls of NPP at different spatial scales (Bai et al. 2008b), plant community structure and succession (Bao

1

Introduction

et al. 2004), species diversity and ecosystem functioning (Bai et al. 2004, 2010b; Wu et al. 2015), and soil fauna (Chen et al. 2015, 2016a, b). In various typical steppe communities, Dong YS and his associates investigated biomass, community composition, and functional diversity of soil microbes (He et al. 2013), and measured soil respiration dynamics consecutively (Dong et al. 2005). In recent years, they have begun to cope with N2O emissions (Peng et al. 2011), examined their responses to water and nitrogen additions and to grazing (Qin et al. 2011; Liu et al. 2010;), and assessed the effects of conversion from grasslands to croplands on different soil organic carbon fractions (Qi et al. 2012). Zheng and her colleagues focused on measurements of greenhouse gas exchanges in the typical grassland ecosystem. They assessed grazing-induced reduction of natural nitrous oxide release from the continental steppe (Wolf et al. 2010), measuring mehane uptake by the steppe as regulated by stocking rates (Chen et al. 2011a, b), determining the spatial variability of GHGs fluxes within the Xilin River catchment of Inner Mongolia (Yao et al. 2010), and monitoring carbon dioxide emissions from steppe soils during the nongrowing season (Chen et al. 2013b). Wang and her associates determined seasonal and interannual variations in water evaporation, energy, and carbon exchange (Hao et al. 2007), partitioned the evapo-transpiration in respect to CO2 fluxes (Huang et al. 2010), discerned the response of ecosystem CO2 exchanges to small precipitation pulses (Hao et al. 2010), and investigated soil bacterial diversity, community structure (Zhou et al. 2007a, 2008), and soil organic carbon content (Cui et al. 2005) as affected by long-term grazing in various typical steppe ecosystems. At the Xilingol research site, the manipulative experiments treated by grazing (Wang et al. 2003), burning (Zhou et al. 2009), and pulse N addition (Tian et al. 2016a, b; Zhang et al. 2016b) have been influential, fruitful, and internationally attractive. Grasshoppers have been the object of particular research emphasis in the typical steppe. Long-term studies of grasshopper ecology have mainly focused on the fauna and food selections of the grasshoppers, and on determining the economic threshold for control guidelines for major pest grasshopper species infesting the region (Kang et al. 2007). In recent years, more research efforts by Kang’s group (Cease et al. 2012) have been placed on understanding the lifehistory strategies, chemical ecology, niche differentiation, and community dynamics of grasshoppers in response to livestock grazing. Research on rodents in grassland ecosystems by Zhang’s group have focused on the population ecology of major species such as Citellus dauricus, voles and Chinese Zokor (Myospalax fontanieri), and on their effects on the steppe communities prior to the year 2000 (Zhong and Bao 1999). Recent studies have dealt with dominance changes in rodent species as influenced by grazing and climate change (Zhang et al. 2003). Readers are referred to the

1.5 Current Advances in Chinese Grassland Ecosystem Studies

following four books for detailed research advances in the typical steppe region: “Typical Steppe Ecosystems of China” (Chen and Wang 2000), “Management of Grazed Ecosystems” (Wang et al. 2003), and “Mechanisms for Maintaining Inner Mongolian Grassland Ecosystems” (Han and Li 2012). The Stipa krylovii typical steppe ecosystem in the agropastoral zone of north China has been intensively studied at Duolun Station research sites. The characteristic themes examined by Li LH and his colleagues and Zhang WH’s group include nutrient use efficiency (NUE) of steppic plants (Yuan et al. 2006), chronic effects of nitrogen addition on community succession (Tian et al. 2016b) and soil microbes (Shen et al. 2011; Liu et al. 2014), root lifespan of dominant plants (Bai et al. 2008a, 2010a, 2015a), GHGs emissions (Zhang et al. 2014a, 2020), and the impacts of land-use changes on the primary production (Zhou et al. 2006) and soil carbon and nitrogen reserves (Zhou et al. 2007b). The multifactor manipulative experiment (MUME) set up by Wan and his colleagues is most representative of the studies regarding climate change and steppe ecosystems in the northern grasslands. In an effort to examine variations of the steppe ecosystem in response to changes of single or combined environmental factors, it has involved as many biotic and abiotic factors as possible—covering both the above- and belowground parts—potentially affecting the structure, function, and process of the S. krylovii steppe ecosystem (provided that the methods and approaches to cope with them were technically feasible or available at that time). The concrete research contents concern: plant traits (Yang et al. 2011a, b), individual plant ecology (Xia and Wan 2008), plant phenology (Xü et al. 2015a, b), species richness (Yang et al. 2012a), NPP and biomass (Lin et al. 2010), root longevity (Bai et al. 2012), photosynthesis (Wan et al. 2009), soil respiration (Xia et al. 2009a; Yan et al. 2010; Yan et al. 2011a), net ecosystem carbon exchange (Xia et al. 2009b; Niu et al. 2010), the carbon cycle (Xia et al. 2014), community structure and composition (Yang et al. 2011b), insects (Song et al. 2015), BVOCs emission (Wang et al. 2012a, c), water use efficiency (Niu et al. 2008; Liu et al. 2009b; Niu et al. 2011), and soil microbes (Zhou et al. 2013). Zhang and his students examined concerted changes in the plant-soilmicrobe complex as affected by grazing (Liu et al. 2015) and the interaction between arbuscular mycorrhizal fungi and soil phosphorus availability in relation to plant community productivity and ecosystem stability in the S. krylovii ecosystem (Yang et al. 2014a); they also unraveled a potential mechanism by which N deposition favors the dominance of grasses over forbs, and established an innovative grassland ecosystem management system for environmental and livelihood benefits in north China (Shen et al. 2018). Jiang Y and his colleagues revealed that environmental changes drive the temporal stability of the steppe ecosystem to some extent

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by altering species asynchrony (Xü et al. 2015a), and identified the antithetical effects of nitrogen and water availability on the community similarity (Xü et al. 2015b). They linked ethylene to nitrogen-dependent leaf longevity of grass species (Ren et al. 2013), evaluated the effects of water and nitrogen additions on the species turnover (Xü 2012), and examined the responses of enzymatic activities within soil aggregates to 9-year nitrogen and water additions in the Stipa krylovii steppe ecosystem (Wang et al. 2015a). It should be stressed here that the cooperative studies between several of the above authors and their foreign colleagues on the typical steppe ecosystems of Inner Mongolia have been most active and fruitful, and have substantially expanded the width and depth of relevant research subjects. Of these, the ones in collaboration with Jianguo Wu on grassland biodiversity and ecosystem functioning in Xilingol typical steppe (Bai et al. 2004), Weixin Cheng on biogeochemistry in a typical steppe (Chen et al. 2010), Jiquan Chen on eddycovariance technique-based research in various Inner Mongolia grasslands (Shao et al. 2013), Elser on plant and insect stoichiometry (Yu et al. 2010; Cease et al. 2012), S Naeem on functions of biodiversity in the typical steppe (Bai et al. 2010b), and a number of German ecologists on exchanges of GHGs (Wolf et al. 2010) are the most influential and have benefited many of their Chinese counterparts. Studies on the alpine meadow steppe and the meadow ecosystems on the Qinghai-Tibet Plateau (QT Plateau for short throughout) are rather systematic and persistent, of which the research at the Haibei Station is most typical. Early works concentrated on the species composition and biomass and/or production dynamics of plants, animals, and microorganisms (Haibei station, 1985–1993). Studies on the alpine meadow ecosystem by Zhao and his colleagues (Zhao et al. 1999) concern herbivory and the energy balance of rodents (Zhao et al. 2004), yaks (Bai et al. 2005), plant species dynamics (Klein et al. 2004, 2005, 2007) and the net exchange of CO2 (Zhao et al. 2006) in response to climate change in the region. Cui XY assessed root biomass and production in a Kobresia humilis meadow ecosystem (Wu et al. 2011). Based on the field evidence, Zhou et al. (2014a) showed earlier leaf-out dates of the plants in the alpine grassland of the eastern Tibetan Plateau from 1990 to 2006. Cao GM’s group measured nitrous oxide (Du et al. 2008) and methane emissions (Cao et al. 2008) in several alpine meadow communities; they also unraveled the thirtyyear variation patterns of aboveground net primary production and precipitation-use efficiency in an alpine meadow (Li et al. 2015a) and examined changes in plant community traits and the soil water status of an alpine Kobresia meadow along different degradation gradients (Li et al. 2015b). Wang and Li (1995) measured the seasonal pattern of soil fungal biomass in different communities of an alpine meadow, which delivered the earliest highly reliable knowledge in this regard.

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In recent years, a series of studies on ecosystem structural traits and functions in response to climate change (Wang et al. 2012c), grazing (Niu et al. 2015), mowing, and N deposition (Zhong et al. 2015) have been continually conducted by Wang SP and his colleagues in the same alpine meadow grassland ecosystem as above. These studies concern soil respiration (Cui et al. 2011), nitrogen transformation and cycling (Chen et al. 2013a; Hu et al. 2010a), GHGs emissions (Li et al. 2014; Wang et al. 2015b), plant phonological and botanical traits (Wang et al. 2014b, c), rodents (Du et al. 2016), and microorganisms (Yang et al. 2013a). They also have examined the responses of ecosystem respiration (Liu et al. 2011) and litter mass loss (Luo et al. 2010a) to warming and grazing during growing seasons, and ascertained the nonadditive effect of species diversity and temperature sensitivity on the decomposition of mixed plant detritus (Duan et al. 2013). Yu GR and his colleagues studied the responses of soil organic matter and CO2 efflux to multiform and low-level N addition in an alpine meadow ecosystem in Dangxiong, Tibet (Fang et al. 2012, 2014). Shi PL and his students examined the effects of litter traits and richness of plant species on carbon and nitrogen dynamics (Jiang et al. 2013a), and figured out the response pattern of ecosystem respiration and its components to fertilization (Jiang et al. 2013b). In addition, Song et al. (2012, 2015) unraveled a plant species coexistence mechanism and the compensatory effects among different plant species and/or species groups on the community stability as affected by nitrogen addition in the alpine meadow. At a regional scale, Yang YH and his colleagues ascertained the determinants of carbon release from the active soil layer and permafrost deposits of Tibetan grasslands (Chen et al. 2016c), linking temperature sensitivity of soil CO2 release to substrate, environmental and microbial properties across the entire alpine zonobiome (Ding et al. 2016a, b), and relating microbial C: N:P stoichiometric traits of soils to microbial community properties and abiotic factors along a 3500 km-long transect on the QT Plateau (Chen et al. 2016d). Yang and his colleagues also established a new means of evaluation by using deep sediment cores, whereby they have built up a permafrost soil carbon sequestration inventory of the QT Plateau (Ding et al. 2016a, b). They showed that edaphic rather than climatic factors control 13C enrichment in the soil and vegetation in the alpine grasslands (Yang et al. 2015b). In addition, they also discerned stoichiometric shifts of surface soils along broader geographical gradients all across China’s grasslands (Yang et al. 2014b), expounded the relationship between vegetation and soil 15 N natural abundances in various alpine grasslands of the Tibetan Plateau (Yang et al. 2013b), and investigated the rain use efficiency across a precipitation gradient on the plateau (Yang et al. 2010b). Meadow steppe ecosystems have been studied continually in northeast China. The research works conducted by Wang

1

Introduction

and his colleagues are the most characteristic and systematic. Unlike in other steppes, their studies concentrated largely on the interaction between animals and plants in relation to vegetation succession and the coevolution of grasses and livestock, which are the most poorly documented aspects of the current grassland ecosystem studies in the nation. Important topics include: the relation between plant species richness and ecosystem multi-functionality (Maestre et al. 2012), the effects of plant spatial distribution patterns on the foraging selectivity of livestock (Huang et al. 2012; Tsegaia et al. 2013), the impacts of large herbivores and grasshoppers on grassland plant diversity (Zhong et al. 2014), and the effects of simulated herbivory on rhizomatous perennial herbs (Gao et al. 2014b). They also examined the effects of altered precipitation on the species composition and structure of insect communities, and the interactive effects of large herbivores and plant diversity on insect abundance. They compared the responses of two contrasting saline-alkaline grassland communities to nitrogen addition during early secondary succession (Bai et al. 2015b). In addition, they researched the effects of warming and nitrogen deposition on the coupling mechanism between soil nitrogen and phosphorus (Zhang et al. 2013), foraging responses of clonal plants to multi-patch environmental heterogeneity (Gao et al. 2012b), as well as the seedling growth of several major plant species in response to parental warming environment (Gao et al. 2012a). Xin and her colleagues have been conducting a long-term manipulative experiment examining the effects of livestock grazing on various aspects of a Stipa baicalensis meadow steppe ecosystem, and a series of new findings has cropped up in recent years (Yan et al. 2011b, 2015). Studies on the desert steppe ecosystem are conducted relatively less often. However, the research on vegetationand community-related aspects is quite unique and inspiring. By drawing on the data and materials collected in three research stations since 1959, the Inner Mongolia Agricultural University Laboratory of Grassland Management led by Dr. Han has systematically summarized the major results in the book “Research on the Chinese Desert Steppe Ecosystem,” wherein many new findings were issued for the first time (Wei et al. 2013b). Studies on the shrubby steppe ecosystem focus on vegetation dynamics, community succession, and natural regeneration and restoration in response to human activities. Of these, the studies conducted by Jiao and her students on seed production, dispersal, establishment, and seed bank of the various shrubby steppe communities occurring in the hillygully areas of the Loess Plateau are the most characteristic (Jiao 2015). In total, the seeds of 202 seed plant species were identified in the regional soil seed bank of these areas, involving 45 shrubby steppe communities. They found that seed removal through soil erosion explained to a large extent

1.5 Current Advances in Chinese Grassland Ecosystem Studies

the scarcity of vegetation on the Loess Plateau (Jiao et al. 2011). They also deciphered the role of the local species pool, soil seed bank, and seedling pool in natural restoration of vegetation on the abandoned slope lands (Wang et al. 2010, 2011, 2013a, b) and examined the effects of rainfall erosion on seedling establishment in relation to micro-topographies (Wang et al. 2012b) and the effects of seed morphology on seed removal and plant distribution in the region. Sandy grassland ecosystem studies have been undertaken in each major sandland. Dong M and Yu FH were the earliest to carry out research on clonal plant ecology, and on sandy clonal plants in the Mu Us sandland in particular. They studied the effects of clonal integration on the survival of sandy grasses (Yu et al. 2004), the effects of reciprocal and coincident patchiness of multiple resources on clonal integration of perennial herbs (He et al. 2011), the expansion, stabilization, and decline of shrubs as affected by habitatspecific demography (Li et al. 2011d), adaptation of rhizome connections to the dryland environment (Yu et al. 2008), and the trade-off between the guerilla and phalanx plant growth forms (Ye et al. 2006) in the sandy grassland ecosystem. Research works by Huang and his students in the Mu Us sandland are fairly systematic and convincing, involving various aspects of the seed ecology for a number of important psammophilous plant species (Huang et al. 2016), such as Psammochloa villosa (Huang et al. 2004a, b, c), perennial grasses (Zhu et al. 2009), Hedysarum leaves (Yang et al. 2010a), and Leymus secalinus (Zhu et al. 2014), as affected by or in response to sand burial, soil moisture status, and changes in precipitation and nutrients. Their in-depth studies also include topics such as the role of mucilaginous pellicle of seeds in seed germination (Yang et al. 2010c), postdispersal and seed removal by ants (He et al. 2013), and sand-stabilizing (Huang et al. 2014), with those regarding degradation of seed mucilage by soil microbes most characteristic and idiographic. Their study on the C:N:P stoichiometry of Artemisia species across northern China unraveled the effects of climate and soils on plant taxonomic traits for the first time (Yang et al. 2015a). They have successfully studied the seed-habitat relation of several dominant plant species occurring in the Junggar Desert, notably Haloxylon ammodendron (Huang et al. 2003), Leymus racemosus (Huang et al. 2004a, b, c), Halocnemum strobilaceum (Qu et al. 2008b), Salsola affinis (Wei et al. 2007), Kalidium capsicum (Qu et al. 2008a, b), and Suaeda corniculata (Yang et al. 2012b), to examine the responses of certain biological and ecological traits of the seeds to salinity, cold stratification, and changes in temperature and light. In addition, they also investigated the aerial and soil seed banks of several desert annual plants (Gao et al. 2014a). The Horqin sandy grassland ecosystem has been intensively studied by the ecologists at the Naiman (Horqin) Sandland Ecosystem Research Station affiliated with the

11

former Lanzhou Institute of Desert Research. Li SG and his colleagues persistently observed micrometeorological changes following the establishment of artificial sage vegetation on sand dunes (Li et al. 2002a), and assessed the grassland desertification status caused by grazing in Inner Mongolia. They investigated the impacts of habitat degradation, topography, and rainfall variability on seed distribution and recruitment in a sand dune grassland community, assessing the influence of vegetation degradation and wind erosion on soil carbon, nitrogen, and phosphorus accumulations in various sandy grassland soils (Li et al. 2009) and monitoring the population establishment processes of two important Artemisia species on the mobile sand dunes as affected by livestock grazing (Li et al. 2002a) and wind (Li et al. 2005). Su and his colleagues investigated variations in soil properties and plant species composition following an age sequence of Caragana microphylla plantations in the Horqin sandland (Su and Zhao 2003), and examined changes in soil properties following the cultivation and fencing of a sandy grassland (Su et al. 2004a). In addition, they systematically examined the influence of shrubs on soil chemical properties of a sandy shrubland (Su et al. 2004b) and the contrasting influences of continuous grazing vs. enclosure on the soil properties in a degraded sandy grassland (Su et al. 2005). Zuo and his colleagues found that plant functional diversity can mediate the effects of vegetation and soil properties on community-level plant nitrogen use in the restoration of a semiarid sandy grassland (Zuo et al. 2016a), which they ascribed to the enhancement of associations among the plant-soil-fungal complex (Zuo et al. 2016b). They investigated changes in carbon and nitrogen storage, vegetation pattern, and the soil degradation status along a restoration gradient in the grassland (Zuo et al. 2009, 2015), and assessed the long-term impacts of different fire frequencies on the vegetation succession in an old-field grassland in the region (Li et al. 2013). The Hunshan Dak sandy grassland ecosystem recently has drawn the attention of a number of researchers, mainly due to its peculiar vegetation physiognomy featured by savanna-like characteristics. Jiang GM’s group has conducted specific studies on the woody plant species Ulmus pumila, the most characteristic tree species in this area, with attention paid to photosynthesis (Jiang et al. 2006a, b; Li et al. 2007), gas exchange and water use efficiency of the elm seedlings (Li et al. 2003), and the soil seed bank (Liu et al. 2009a). They measured gas exchange, photochemical efficiency, and leaf water potential of three Salix species, and examined the leaf osmotic potential of 104 plant species in relation to the habitats and plant functional types (Liu et al. 2003a, b). They estimated the biomass carbon storage and net primary production of a number of different sandy stands (Li et al. 2011a, b), comparing the photosynthetic traits between the legume and nonlegume shrubs (Niu et al. 2003), and examining the photosynthesis, transpiration, and water use

12

efficiencies of several psammophilous plants in response to livestock grazing (Peng et al. 2007). In addition, inquiries on the control of sandstorms for strategies of ecosystem management and on the means of restoring damaged sandlands in the region have also been conducted with great effort (Jiang et al. 2006c). Studies on the Xinjiang montane grassland and typical desert ecosystems are rather extensive and unique. Targeting an important shrubby legume, Eremosparton songoricum, distributed in the Gurbantünggüt Desert, Zhang and his students explored its pollination mechanism (Shi et al. 2010), recruitment approach (Zhang et al. 2011a), and conservation means (Zhang et al. 2011b), and examined the effects of sand burial, seed bank, and soil moisture status on the population regeneration of the species. Li’s group examined the relationship between the water use and carbon gain of a halophytic desert community (Ran et al. 2012), and detected the ecophysiological response and morphological adjustment of the desert shrubs to summer precipitation change (Xü et al. 2007) and to pulse raining events in particular (Xü et al. 2006). Zeng and his colleagues specifically studied the water and nutrient dynamics in the surface roots and soil of a hyper-arid desert community (Zeng et al. 2006), revealed the water relation characteristics (Zeng et al. 2002), growth control, physiological characteristics, and ion distribution of Alhagi sparsifolia, a dominant desert plant species (Zeng et al. 2008), and evaluated the influence of floodwater on the vegetation composition and regeneration of a Taklimakan desert oasis. Ma and his colleagues have engaged in long-term ecological observations and field surveys of the wildlife species inhabiting the various Xinjiang ecosystems. Their specific topics of study include the distribution, population size and dynamics, breeding ecology, conservation biology, and ecosystem function of the snow leopards colonizing the Muzat Valley of the Tianshan Mountains (Ma et al. 2006a), the saker falcon ranging in the desert (Ma et al. 2006b), and the golden eagle inhabiting the central Kunlun Mountains (Ma et al. 2010a, b). Luo’s group conducted modeling studies on evapo-transpiration of the desert ecosystem (Li et al. 2011c) and land-use scenario analysis at the regional scale (Luo et al. 2010b). In the Gurbantünggüt Desert, Zhang and his students conducted research on the biomass allocation pattern of the ephemeral and annual plants (Zhou et al. 2014b), and on the desert mosses and annuals in response to various stresses (Zhou et al. 2011a, b). They have persistently conducted studies focusing on the microstructure and formation (Zhang et al. 2005), spatial distribution patterns (Zhang et al. 2007b), and variations in microalgal species composition at different successional stages (Zhang et al. 2009), as well as CO2 exchange (Su et al. 2012, 2013) of the biological soil crusts occurring on the deserts. In addition, they also examined variations in microbial activity across a gradient of

1

Introduction

nitrogen addition (Zhou et al. 2012) and evaluated the influence of the microstructure of microbiotic crusts on wind erosion (Zhang et al. 2006a, b, c, 2007b). In the Junggar Basin, Ma and her students waged several studies on the carbon stable isotope characteristics of a number of desert plants (Ma et al. 2005, 2007a, b, 2012) and different soils (Ma et al. 2009). They have been also engaged in systematic studies on the water resource availability and water-use efficiency of desert plants in the Hexi Corridor Desert (Cui et al. 2011, 2015). Li et al. (2010) evaluated the influence of groundwater depth on the plant species composition and community structure of Cele oasis, investigated variations in the ecophysiological traits of Calligonum roborovskii with respect to decreasing soil water content along an altitudinal gradient on the Kunlun Mountains (Zhu et al. 2010), and discerned the water relation of Alhagi sparsifolia growing in the southern fringe of the Taklimakan Desert (Li et al. 2002b). Hu and his colleagues investigated the plant diversity and productivity patterns (Hu et al. 2009b) and measured emissions of GHGs in a montane steppe ecosystem occurring on the central Tianshan Mountains (Li et al. 2012). They also attested to the succession sequence of the montane steppe in response to different years of fencing (Hu et al. 2009a, b). Large-scale studies on the Chinese grassland zonobiome have been advancing rapidly in recent years, of which the following research works are most relevant and influential. Fang JY and his colleagues detected significant shrinkage and disappearance of the grassland-based lakes on the Inner Mongolian Plateau during the past several decades, with particularly rapid losses of the lakes occurring since the late 1990s (Tao et al. 2015). They found widespread decreases in the inorganic carbon stock of topsoils and significant soil acidification in various grasslands that occurred during the 1980s and the 2000s, and unraveled the large-scale pattern of biomass partitioning of Chinese grasslands as a whole (Yang et al. 2010d). In addition, they related the variability in aboveground net primary production of the world’s grasslands to precipitation at a global scale (Yang et al. 2008). He JS and his colleagues examined the taxonomic, phylogenetic, and environmental trade-offs between leaf productivity and persistence (He et al. 2009), synthesizing the general patterns of the leaf nitrogen-to-phosphorus ratio (He et al. 2008) and the leaf carbon-to-nitrogen ratio across the grassland biomes of China (He et al. 2006a), and testing the generality of the leaf trait relationship in the Tibetan Plateau grasslands (He et al. 2006b). In addition, they also examined the effect of geographical range size on the plant functional traits and relationships between plants, soils, and climates in Chinese grasslands (Geng et al. 2012), and revealed that alpine climates may alter the relationship between leaf and root morphological traits to varying extents (Geng et al. 2014). Hu investigated the precipitation-use efficiency of terrestrial plants along a 4500-km grassland

1.6 Treatment of This Volume

transect (Hu et al. 2010b), synthesized the effects of livestock exclusion on carbon dynamics in the grasslands nationwide (Hu et al. 2016), and assessed vegetation controls over ecosystem water use efficiency within four grassland ecosystem types in China. Bai E and her students figured out the aridity threshold for controlling ecosystem nitrogen cycling in the temperate grassland ecosystem zone (Wang et al. 2014a). Grassland studies in northern China have been briefly summarized by J. Ellis, XS Zhang, JG Wu, and several other grassland researchers, the resultant book being probably one of the earliest English writings pertaining to Chinese grassland ecosystems (NRC 1992). The above two sections briefly reviewed the history and current advances of ecosystem studies for only the steppic and semi-steppic grassland ecosystem types. The non-steppic and man-made grassland ecosystem types, such as the desert rangeland in the northwest and the meadow grassland in the northeast, will be reviewed and discussed in the coming individual chapters of the book. In summary, one sees that the research dimensions differ greatly among different grassland types and different regions. The studies on the typical, alpine, and meadow steppes as well as the sandy grassland are apparently more intensive and extensive, whereas those on the desert rangeland, the meadow grassland, and the montane and shrubby steppes are relatively inadequate. Besides, much like the situation facing our international counterparts, research on both the structure and function of soil fauna and microorganisms is extremely insufficient, and the research on belowground processes deserves particular attention and substantial promotion in the future. Nowadays, holistic and concerted ecosystem studies covering as many as possible structural components and functional processes simultaneously as a whole—as they were done just two or three decades ago—are becoming more and more difficult to realize at most of the grassland ecosystem research sites in China due to the prevalent individualized tendency of ecological research currently, making it extremely difficult to construct a complete diagram of the matter cycling or energy flowing at current time scales in any grassland ecosystem. Research papers and works concerning Chinese grassland ecosystems published up to date are roughly categorized according to the relevant themes and summarized in Table 1.2.

1.6

Treatment of This Volume

This volume was written following three thematic lines. Firstly, it is concerned with the natural grasslands in China. Natural grassland here refers to the zonal (true) grasslands

13 Table 1.2 Total literature and theme-based distributions concerning studies of Chinese grassland ecosystemsa Theme Vegetation Dynamics and succession Community structure Canopy biomass and NPP Diversity and stability Roots Nutrient cycling Energy balance Water and heat fluxes Soil property Soil respiration Nitrogen transformation GHGs emissions Decomposition of litter Soil fauna Soil microbes Herbivores Insect ecology Rodent ecology Avian ecology Land-use Management Restoration Resources Total

CSCD paperb 890 160 526 705 248 117 221 247 666 203 120 394 76 47 66 127 631 401 20 25 255 465 382 327 6992

SCI paper 168 18 17 102 68 18 49 21 166 32 40 99 42 25 11 9 24 4 2 1 76 71 28 21 1112

Books 9 13 8 7 5 1 2 1 3 4 1 6 6 1 2 15 3 6 6 1 20 21 10 8 159

Note: aSummarized by Hou LY ([email protected]); bIncluded by the Chinese Science Citation Database

(steppes), the azonal (nontypical) grasslands (meadows, tussocks, and marshes), and the rangeland (sandlands and deserts). Secondly, it involves to a certain extent the resource aspects of the grasslands, in which important regional grasslands such as the Inner Mongolian grassland, the Qinghai-Tibet grassland, the Xinjiang grassland, and the northeast China grassland have been elaborated on in terms of the yield, stocking rate, and general natural features. Thirdly, it focuses mainly on the ecosystem aspects of the grasslands, providing wide coverage on all of the major grassland types in China. One can see that strong emphases have been given to the structural aspects such as the type, distribution, succession, and biotic composition, as well as soil, water, and atmospheric backgrounds or baseline characteristics, while much less emphasis is placed on the functions and processes of the grassland ecosystems and on the utilization or management of the grassland resources. This is mainly because the latter-mentioned topics will be specifically discussed in the companion books of the series.

14

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1

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1

Introduction

Yu FH, Dong M, Krusi B (2004) Clonal integration helps Psammochloa villosa survive sand burial in an inland dune. New Phytol 162:697–704 Yu FH, Wang N, He WM, Chu Y, Dong M (2008) Adaptation of rhizome connections in drylands: Increasing tolerance of clones to wind erosion. Ann Bot 102:571–577 Yu Q, Chen Q, Elser JJ, He NP et al (2010) Linking stoichiometric homoeostasis with ecosystem structure, functioning and stability. Ecol Lett 13:1390–1399 Yu Q, Wilcox K, Pierre LK, Knapp AK et al (2015) Stoichiometric homeostasis predicts plant species dominance, temporal stability and responses to global change. Ecology 96(9):2328–2335 Yuan ZY, Li LH, Han XG, Chen SP, Wang ZW et al (2006) Nitrogen response efficiency increased monotonically with decreasing soil resource availability: a case study from a semi-arid grassland in northern China. Oecologia 148:564–572 Zeng FJ, Zhang XM, Foetzki A, XY LI et al (2002) Water relation characteristics of Alhagi sparsifolia and consequences for a sustainable menegement. Sci China (Ser D) 45(Suppl):125–131 Zeng FJ, Timothy M, Bleby P et al (2006) Water and nutrient dynamics in surface roots and soils are not modified by short-term flooding of phreatophytic plants in a hyperarid desert. Plant Soil 279:129–139 Zeng J, Zeng FJ, Arndt SK, Guo HF et al (2008) Growth, physiological characteristics and ion distribution of NaCl stressed Alhagi sparsifolia seedings. Chin Sci Bull (Suppl) 53:169–176 Zhang HD (1948) The vegetation of Paracel Islands. Sunyatsenia 7(1/2) Zhang XZ (1955) A preliminary report on Sinkang Acridiidae with special reference to their egg capsules and distribution. Acta Entomol Sin 5(4):463–474 Zhang ZT (1960) Preliminary investigation on the types and productivity of the Hulun Buir grassland. Unpublished Zhang JW (1963) Basic characteristics and zonal significance of the alpine steppe on southeastern Qiangtan plateau. Acta Phys Sin 1 (1):131–140 Zhang RZ, Lin YL (1981) On the development of mammalian zoogeography in China for the last thirty years. Acta Theriol Sin 1(1):3–13 Zhang ZT, Liu Q (1992) Rangeland Resources and Utilization in the Main Pastoral Regions of China. China Science and Technology Press, Beijing Zhang ZB, Pech R, Davis S, Shi D et al (2003) Extrinsic and intrinsic factors determine the eruptive dynamics of Brandt’s voles Microtus brandti in Inner Mongolia, China. Oikos 100:299–310 Zhang BC, Zhang YM, Zao JC (2005) Composition and ecological distribution of the algae living in the Gurbantunggut desert of Xinjiang. Acta Botan Boreali-Occiden Sin 25(10):2048–2055 Zhang HM, Hu JZ, Gong MH (2006a) Summer community of ungulates in Shiqu County, Sichuan Province. Sichuan J Zool 25(1):34–39 Zhang YM, Yang YF, Wang LJ (2006b) Seasonal dynamics in production and allocation of Phragmites communis wetland in Sanjiang Plain. Chin J Grassl 28(4):1–5 Zhang YM, Wang HL, Wang XQ, Yang WK, Zhang DY (2006c) The microstructure of microbiotic crusts and its influence on wind erosion of a sandy soil surface in the Gurbantunggut desert of northwestern China. Geoderma 132:441–449 Zhang XS, Sun SZ, Yong SP, Zhuo ZD, Wang RQ (2007a) Vegetation and its Geographic Patterns in China. Chinese Geology Press, Beijing Zhang YM, Chen J, Wang L, Wang XQ, Gu ZH (2007b) The spatial distribution pattern of biological soil crusts in the Gurbantunggut sesert of northern Xinjiang, China. J Arid Environ 68:599–610 Zhang GL, Shi XZ, Gong ZT (2008) Retrospect and perspect of soil geography in China. Acta Pedol Sin 45(5):792–801 Zhang BC, Zhang YM, Zhao JC et al (2009) Microalgal species variation at different successional stages in biological soil crusts of the Gurbantunggut desert, northwestern China. Biol Fertil Soils 45:539–547

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2

Overview of Chinese Grassland Ecosystems

Abstract

This chapter generally elaborates upon the fundamental characteristics of Chinese grassland ecosystems as a whole. Firstly, it introduces the major types and distribution patterns of Chinese grasslands in terms of vegetation, ecosystem, and land use. Secondly, it makes simple accounts of the biotic composition characteristics of Chinese grassland ecosystems, with emphasis on those pertaining to the steppe plants, mammals, rodents, insects, and microorganisms. In addition, it discusses the current regimes of soil and vegetation degradation of Chinese grasslands, and points out a trend of the delinking of the grasslands with livestock in the country that deserves special attention. Keywords

Grassland type · Flora · Fauna · Land use · Degradation

China lies in the eastern part of Asia, borders the Pacific Ocean on its east, and is not far from the Indian Ocean to its southwest. It occupies a geographical extent latitudinally between 3
510 and 53
34’N and longitudinally from 73
400 to 135
340 E, spanning a distance of roughly 5500 km from north to south and 5200 km from west to east. The land territory totals some 9.6 million km2, while its marine area amounts to 4.73 million km2, consisting primarily of four large seas, i.e., the Bohai Sea, the Huanghai Sea, the East China Sea, and the South China Sea (NBEP 1998). China’s various grasslands possess a total area of roughly 3.93 million km2 (Table 2.1), which accounts for approximately 12.5% of the total area of the world’s grasslands (Suttie et al. 2005) and 41.41% of China’s total land area, of which about 84.3% is utilizable (Liu et al. 1996). China’s grassland area is about three times that of the croplands and two times that of the forests within the country. The

# Springer Nature Singapore Pte Ltd. 2020 L. Li et al., Grassland Ecosystems of China, Ecosystems of China 2, https://doi.org/10.1007/978-981-15-3421-8_2

grasslands constitute an important component of the natural resources in China. Not only do they provide bases for livestock grazing and animal husbandry production within the broad pastoral regions containing a population of over 20 million people, but they also play a critical role in maintaining the national security in environments and food provisioning for the whole country. This chapter elaborates on the general characteristics of Chinese grasslands, with emphasis on the natural and social aspects that have played important roles in forming, shaping, and modifying the grasslands’ historical and current regimes. In a broad sense, there are three important types of natural grasslands that occur in China, including the temperate grassland, the alpine grassland, and the subtropical tussock grassland, which generally consist of xeromorphic vegetation in nature. The temperate steppes are composed primarily of temperate and cold-temperate herbaceous plants and are distributed broadly across the entire temperate zone from Xinjiang to Inner Mongolia and northeast China, with species of the genus Stipa being the most predominant, vastly distributed and representative species. The alpine grassland consists more often of cold-tolerant, hygrophilous forbs, and occurs mostly on the Qinghai-Tibet Plateau, with the sedge swards most prevalent. By contrast, tussock grasslands and savannas consist predominantly of thermophilous and drought-resistant perennial herbaceous plants, accompanied usually by evergreen or deciduous shrub species that are morphologically ordinary and, at times, some thorny or succulent shrubs in the dry-hot valleys. A few scattered dwarf tree species are also occasionally found in the stands, all in which species of the genus Heteropogon are the most prominent. They occur most vastly in the subtropical and tropical regions of southwest China (Li et al. 1980a). In the semiarid temperate zone of northern China, zonal steppes are alternately distributed, forming a vast steppe region and constituting an important part of the Eurasian

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24

2 Overview of Chinese Grassland Ecosystems

Table 2.1 Total land area, grassland acreage, and their provincial distributions in Chinaa

Province Beijing Tianjin Hebei Shanxi Inner Mongolia Liaoning Jilin Heilongjiang Shanghai Jiangsu Zhejiang Anhui Fujian Jiangxi Shandong Henan Hubei Hunan Guangdong Guangxi Hainan Sichuan Guizhou Yunnan Tibet Shaanxi Gansu Qinghai Ningxia Xinjiang National total a

Land area (104 km2) 1.64 1.13 18.80 15.68 114.53

Grassland acreage (hm2) 394,816 146,604 471,2140 4,552,000 78,804,483

Prop. of grassland in total land (%) 24.07 12.97 25.06 29.03 68.81

14.59 19.09 45.46 0.63 10.12 10.37 13.99 12.38 16.71 15.67 16.57 18.56 21.19 17.81 23.67 3.40 56.26 17.57 38.17 120.48 20.56 42.56 70.82 5.18 165.09 948.68

3,388,848 5,842,182 7,531,767 73,333 412,709 3,169,853 1,663,179 2,047,957 4,442,334 1,637,974 4,433,788 6,352,215 6,372,668 3,266,241 8,698,342 949,773 22,538,826 4,287,257 15,308,433 82,051,942 5,206,183 17,904,206 36,369,746 3,014,067 57,258,767 392,832,633

23.23 30.06 16.57 11.64 4.08 30.57 11.89 16.54 26.58 10.45 26.76 34.23 30.07 18.34 36.75 27.93 40.04 24.40 40.11 68.10 25.32 42.07 51.36 58.19 34.68 41.41

Adapted from Liu et al. (1996)

steppes. The alpine steppes are generally zonal and confined mostly to the QT Plateau. In stark contrast, the tussock grasslands are generally secondary and azonal, scattered sporadically across the mountain slopes, rolling terraces, and dry and hot river valleys of the mainland as well as on the basaltic tablelands of the northwestern Hainan Islands. The total area of China’s temperate grasslands approximates 1.8876 million km2, accounting for about 48.1% of the country’s total grassland area. The temperate grasslands form a broad zone extending from the Northeast Plains in the east to Xinjiang in the west and spanning a latitudinal range from 35
to 51
N (Fig. 2.1). They border mainly Mongol grasslands to the north and parts of the former Soviet Union to the northwest and northeast. They are bounded on the west by the Central Asian deserts and

steppes and by the coniferous and/or broadleaved and coniferous mixed forests in the east and northeast, whereas in the south they are bounded by the temperate deciduous broadleaved forests. The main body of the temperate grasslands occurs on the Inner Mongolia Plateau, and an eastward extension occupies large areas of northeast China, while a southwesterly extension involves the Loess Plateau. In the farther western reaches of China, the zonal alpine grasslands are widely and predominantly distributed across almost the entire Qinghai-Tibet Plateau, with a total area of some 1.4096 million km2—about 35.9% of the country’s total grassland extent. By contrast, the remaining 16% is trans-zonally distributed mainly in the various subtropical areas, occurring in the form of scattered tussock stands. In addition, a substantial portion of the areas previously occupied by natural grasslands has been converted into croplands or forage meadows in the north, whereas some seminatural grasslands have derived largely from the clearcutting of forests and woodlands in the south. In a narrow sense, however, various steppes occupy a total area of some 1.33 million km2, of which the temperate steppes total 0.75 million km2 while the alpine steppes amount to roughly 0.58 million km2. The desert rangelands amount to 0.63 million km2 in total, with the temperate steppic desert, the temperate desert, and the alpine desert totaling 106,734, 450,608 and 75,278 km2, respectively. The meadow grasslands possess a total area of some 1.06 million km2, including lowland meadows (252,196 km2), montane meadows (167,189 km2), and alpine meadows (637,206 km2). By contrast, the tussock grasslands total 0.51 million km2, made up of warm tussocks (184,477 km2), hot tussocks (316,139 km2), and savanna (8631 km2), respectively (Liao and Jia 1996). Historically, grasslands in China have been used for centuries as important animal husbandry production bases in association with the concurrent evolution of nomadic nationalities and their characteristic cultures across the broad areas of northern China. Currently, the subsistent livelihood of some 80 million people directly relies on grassland-based animal husbandry nationwide. The grasslands cover the chief headwater areas where several large rivers originate, including the Yangtze River and the Yellow River. A large portion of the grasslands also lies in the ecologically fragile zones where major sandstorms have occurred frequently in recent decades. Natural grasslands are rich in animal and plant resources, which provide raw materials for various economic sectors, including textile and clothing manufacturing, food and milk production, the chemical and leather industries, medicine making, as well as the ecotourism and hunting industries. Last but not least, far-away portions of the grasslands border many other countries and provide living space for minority peoples, and are thus critical for the peaceful and harmonic coexistence of multi-nationalities. The primary characteristics of Chinese grasslands are summarized as follows.

2.1 Broad Distribution and Diverse Grassland Types

25

Fig. 2.1 Map of Chinese grassland types (Image regeneration courtesy of CY Song)

2.1

Broad Distribution and Diverse Grassland Types

Chinese grasslands may be distinguished into two divisions, namely the typical grasslands (steppes) and the atypical grasslands (rangelands), each making up roughly 33.8% and 66.2% of the country’s total grassland area, respectively. Typical grasslands include two subdivisions, i.e., the zonal natural grasslands that are distributed mainly in the Northeast Plains, Inner Mongolia, Xinjiang, and the Qinghai-Tibet Plateau, and the zonal seminatural grasslands that occur primarily on the Loess Plateau and in the northern agro-pastoral transitional region involving several northern provinces. The vegetation is essentially that of steppe. The atypical grasslands also include two subdivisions, namely the derived grassland (meadows, deserts, tussocks) and the artificial grassland. The deserts are mostly zonally distributed across

the broad northwest, while the meadows are centered in the northeast and on the Qinghai-Tibet Plateau. The tussocks occur azonally and are interspersed across various forest regions. The steppes are most typical and principal of Chinese grasslands. They constitute a very important portion of the Eurasian steppes, being among the broadest of their kind in the world. On the Eurasian continent, the steppe generally shows a west-east distribution pattern, spanning about 110 longitudinal degrees roughly from 27
E to 128
E (Li et al. 1980a, b; Lavrenko and Karamysheva 1993), and ranging from the temperate zone down to the tropics (Coupland 1993). Numata once separated Asian grasslands into two categories: monsoonal and arid (Coupland 1993). He considered that climax steppes occur only in arid and semiarid regions as well as in alpine areas. It turns southward and enters into China at the eastern portion of the Mongolian Plateau at roughly 49
N. This trend is closely associated with

26

2 Overview of Chinese Grassland Ecosystems

its distance away from the continent to the sea. The southeastern half of China is mainly influenced by monsoons coming from the South China Sea, bringing about a prevalently warm and moist climate. Towards the northwest, however, the monsoons’ influence gets gradually reduced, whereas the influence of high-pressure air currents from Siberia and Mongolia becomes increasingly intensified, bringing about a gradual increase in aridity. This is fully reflected by the sequential or serial occurrences of forest, grassland, and desert along the northwesterly direction, the trend of which is rather comparable to the general distribution pattern of the vegetation in the inner Asian continent, although opposite in direction. All these factors corroborate or attest to the assumption that arid deserts occur without exception in the center of the continent, while moist forests tend to be present in the seaward areas, and grasslands generally lie between the two. The vast majority of China’s natural grasslands exist in the temperate zone ranging from 35
to 51
N in the south to north direction, spanning a distance of about 2500 km. In this expansive zone, the relief supporting the grassland vegetation increases southwestward little by little in elevation, which causes a counteractive effect on the temperature change. Therefore, the hydrothermal regimes of the whole steppe zone generally remain temperate semiarid to semi-humid. According to RRC, Chinese grasslands comprise 18 major types (Table 2.2). Regionally, 11 key pastoral areas are recognized, including Hulun Buir, Horqin, the Xilingol, and Ulanqab grasslands of Inner Mongolia, the Ili and Altay grasslands of Xinjiang, the Songnen grassland of northeast China, the Aba and Ganzi grasslands of northwestern Sichuan, the Qinghai Lake-surrounding grassland, and the Gannan grassland of Gansu (Zhang and Liu 1992).

2.2

Table 2.2 Chinese grassland types and their areas Grassland type Temperate meadow steppe Temperate typical steppe Temperate desert steppe Alpine meadow steppe Alpine typical steppe Alpine desert steppe Temperate steppic desert Temperate desert Alpine desert Warm tussocks

Acreage (hm2) 14,519,331

Prop. in total (%) 3.70

References Zhu et al. (1996)

41,096,571

10.45

Miao (1996a, b)

18,921,607

4.82

6,865,734

1.75

41,623,171

10.59

9,566,006

2.44

Shi and Wang (1996) Xue (1996)

10,673,418

2.72

Miao (1996a, b)

45,060,811 7,527,763 6,657,148

11.47 1.92 1.69

Song (1996) Su (1996) Liu and Wu (1996) Wang et al. (1996) Wu (1996) Zhou and Zhang (1996) Wu and Liu (1996) Wang et al. (1996) Song (1996) Liu and Wu (1996) Sun et al. (1996) Li (2017)

Warm shrubby tussocks Hot tussocks Hot shrubby tussocks Savanna

11,790,493

3.00

14,237,195 17,376,693

3.62 4.46

863,144

0.22

Lowland meadow

25,219,621

6.40

Montane meadow Alpine meadow

16,718,926 63,720,549

4.26 16.21

Marsh Sporadic grasslands National total

2,873,812 37,520,640

0.73 9.55

392,832,633

100

Guo and Cui (1996) Xue (1996)

Liao and Jia (1996)

Unique Flora

A total of 31,362 species of vascular plants have been recorded in “Flora of China,” distributed across 3328 genera and 312 families, of which 2129 are ferns and lycophytes, 237 are gymnosperms, and 28,995 are angiosperms. Of the species, some 6352 are recognized as grassland species, which belong to 1545 genera of 246 families, including 16 species of lichens, 31 species of ferns, 291 species of pteridophytes, 88 species of gymnosperms, and 5926 species of angiosperms (Chen 1994). The families Leguminosae and Gramineae contain the most numerous species (Table 2.3), while Astragalus, Carex, and Oxytropis are the largest genera (Table 2.4). Some 1887 major grassland or forage species have been recorded and numbered in the aforementioned nationwide baseline survey of grasslands (Liao and Jia 1996), while roughly 940 grassland species of 83 families

Table 2.3 Major families of the grassland plants in Chinaa Family Leguminosae Gramineae Compositae Cyperaceae Rosaceae Chenopodiaceae Liliaceae Polygonaceae Salicaceae Others (237) Total (246) a

Genus 125 210 136 24 40 38 20 11 3 938 1545

Adapted from Chen (1994)

Species 1157 1028 532 350 222 183 150 135 116 2479 6352

Subspp. 6 15 1 1 8 3 5 8 8 3 29

Var. 69 98 5 7 11

84 303

2.3 Highly Adapted Steppe Plants

27

Table 2.4 Top 14 genera of the grassland plants in Chinaa Genus Astragalus Carex Oxytropis Poa Roegneria Salix Allium Polygonum Artemisia Caragana Indigofera Desmodium Saussurea Hedysarum Others (1531) Total (1545) a

Spp. (no.) 276 181 124 96 74 80 73 68 66 65 63 54 53 48 5031 6352

Prop. (%) 4.35 2.85 1.95 1.51 1.16 1.26 1.15 1.07 1.04 1.02 0.99 0.85 0.83 0.76 79.20 100.00

Adapted from Chen (1994)

were listed and described in the inventory book series “Forage Plants in China” as the most common (Jia 1995). The floristic composition of Chinese grasslands is much more species-rich than that of the North American grasslands and the grasslands of the former Soviet Union, owing largely to China’s complex environments, especially within the Qinghai-Tibet Plateau.

2.3

Highly Adapted Steppe Plants

Arid and cold climates prevail in the steppe zone of north China. Steppe plants have evolved a set of morphological traits and features in response and adaptation to the harsh conditions. They are generally characterized by ubiquitously xeromorphic features such as shrunken leaf area, inward-curled leaf blade, sunken stomata, and well-developed protective mechanical tissues, with Stipa spp. particularly affected. In addition, their underground parts are usually robustly developed, with densities well exceeding that of the canopy—a reflection of their adaptation to the arid environments. For most species, their roots are shallow and concentrated at the 0–30 cm soil layer, with the fine roots being much shallower in distribution. Many plants form tight bunches encompassed at the base by residuals to avoid overheating in the summer and bitter cold in winter, such that their regenerative buds and seedlings can survive. For the alpine steppe plants, their adaptation to the high-elevation and cold environment is characterized by taking on the ecologically frigid-xerophytic to frigid-mesophytic growth forms. The developmental rhythms of the steppe plants are strongly controlled or regulated by the steppe climate. The chief dominant plant species reach the peak growth period mostly between July and August, a time at which

precipitation and temperature both are optimal, favoring their growth and phytomass accumulation to the full extent. The seasonal growth trend is highly variable between years, depending largely on the precipitation magnitude and its seasonal allocations. In drought years, some plants cannot reproduce sexually, their seedlings being weak and withering rapidly, whereas in years with abundant rainfall, not only are plants of luxuriant foliage, but can also flower and fruit plentifully. The means by which steppe plants propagate is a persuasive reflection of the harsh conditions they face. Although capable of flowering and fruiting normally and regenerating sexually, they more often take on vegetative propagation as their primary means. Take Leymus chinensis and Stipa spp., the most conspicuous steppe species, as examples; the former proliferates primarily by means of rhizomatous propagation because its sexual reproduction is constrained in three aspects: firstly it cannot yield enough seeds, secondly most of the seeds borne are unviable, and thirdly the germination rate of the viable seeds is extremely low. By contrast, the Stipa species propagate and regenerate more frequently by having their young individual shoots arise from tillering buds, which hide within the base and are perfectly sheathed by their parent bunches. Life-forms can also reflect the characteristics of the environment and the strategies with which plants survive (Suttie et al. 2005). The life-form of the steppe plants is highly differentiated and diversified in Chinese grasslands. According to “Vegetation of China” (VOC), the following are the commonly recognized life-forms occurring in the various grassland habitats. Trees, which mostly are perennial and mesophytic, occur chiefly in the sandy grassland in sparse patches, and form a very unique landscape known as the temperate savanna. Only a few tree species are recognized to appear within the grassland, such as Pinus sylvestris var. mongolica which is widely distributed in the meadow steppe occupying the western piedmonts of the Greater Hinggan Mountains, two elm species (Ulmus pumila and U. macrocarpa) which co-dominate the Hunshan Dak sandland, and Picea meyeri and Populus davidiana which are scattered on the shady slopes of small hills in the typical steppe region. Shrubs and dwarf shrubs are perennial and xerophytic, with Caragana spp. being the most typical. Although originating from mesomorphic types, these steppe shrubs have become better adapted to the arid environment of the steppe climate zone. Others are xeromesophytic, such as Prunus sibirica, which often can form a shrub synusia in the meadow steppe of the Songliao Plain, leading to a shrub stand-like appearance. Semishrubs and dwarf semishrubs can be dominant in the arid region, the dominance of which increases with aridity. In the humid meadow steppes their role is insignificant and negligible. In the typical steppe with intermediate water

28

2 Overview of Chinese Grassland Ecosystems

status, some xerophytic dwarf semishrubs occur in small amounts as associates, yet they can become dominated at overgrazed sites, at which Artemisia frigida and Kochia prostrata are most typical. Thymus mongolicus usually occupies gravelly soils in this area, becoming a dominant or constructive species on the slopes, and forming the T. mongolicus formation with dotted clumps of its prostrate twigs on the ground, which is most characteristic of the shrubby typical steppe. When entering the desert steppe, xerophytic dwarf semishrubs become substantially heightened in their importance, becoming stable dominant constituents or even constructive species, the most representative of which include Hippolytia trifida, Ajania achilloides, and Artemisia dalailamae. Present in the sandy steppe are some tall xerophytic semishrubs, such as Artemisia halodendron and A. ordosica, which are commonly found as dominants in the various sandland communities. “Functional group” is the extended term of “life-form,” which is assigned by not only structural characteristics, but also physiological and functional traits such as photosynthesis pathways to divide C3/C4 plants, nitrogen-fixing capacity to distinguish the N2 fixers from the non-nitrogen fixers, and longevity characters. Yin and Li (1997) listed a total of 533 C4 plant species that occur in the various Chinese terrestrial ecosystems, which belong to 160 genera and 24 families. Of these, 97 are dicotyledons, and 436 are monocotyledons,

with 324 in the family Gramineae, 108 belonging to Cyperaceae, and 37 in Chenopodiaceae. Tang and Liu (2001) estimated that among the 2326 vascular plant species occurring in Inner Mongolia, some 125 species of 57 genera are C4 plants. Wang et al. (1997) reported that 89 C4 species are commonly found in the grasslands of northeast China.

2.4

Infertile Soils and Low Productivity

Grassland soils are generally diverse and regionally characteristic in China. However, the fertilities of most of the soil types are relatively low, except for those occurring in the humid and frigid-humid regions where decomposition of plant residuals and humus is weak while plant production is relatively high. The general fertility status for the bulk of the soils can be described as lacking in nitrogen, deficient in phosphorus, while adequate in potassium. As a result, the forage yield and the stocking capacity of the pastures are both just passable (Table 2.5). Shen et al. (2016) estimated that the mean aboveground biomass of the nation’s natural grasslands during the period 1982–2011 was about 178 g m2, with an increasing rate of 0.4 g m2 yr.1 detected; the mean net primary productivity ranged from 89 to 320 gC m2 yr.1 among the various natural grasslands during the same period, with an average

Table 2.5 Productivity and the soil fertility level for major types of Chinese grasslandsa Region NWb

SEc

QTd

a

Total nitrogen (%)

Soil type Meadow soil

SOMe (%) 6–9

Black soil Chernozem Chestnut soil Brown soil Desert soil Yellow-brown earth Yellow earth

5–8 3–7 1–4 0.5–1 0.2–0.8 1–4

0.256–0.695 0.129–0.431 0.018–0.197 0.040–0.105 0.028–0.073 0.060–0.148

5–10

0.144–0.570

Red earth Latosol Torrid earth Black felty soil Soddy felty soil Cold calcic soil

4–7 8–10 3–4 10–15 9–10 1.5–3.5

0.101–0.340 0.090–0.305

Frigid calcic soil

1–3

0.104–0.166

Cold brown calcic soil Frigid desert soil

1–2

Grassland type Lowland meadow Meadow steppe Meadow steppe Typical steppe Desert steppe Typical desert Warm shrubby tussock Hot shrubby tussock Warm tussock Hot tussock Savanna Alpine meadow Alpine meadow Alpine meadow steppe Alpine typical steppe Alpine desert steppe Alpine desert

0.268–0.584

0.4–0.6 b

c

d

Yieldf (kg/hm2) 1730

SRg (SU/hm2) 1.92

1465 1465 889 455 329 1769

1.26 0.67 0.36 0.3 0.24 2.17

2527

2.78

2643 2643 1770 882

3.33 3.33

307

0.28

284

0.29

195

0.16

1.02

117 e

0.11 f

Note: Adapted from Zhang (1996); Northwest China; Southeast China; Qinghai-Tibet Plateau; Soil organic matter; Dry weight of hay; g Stocking rate in sheep unit

2.6 Substantial Shrinkage of Within-Grassland Water Bodies

29

Table 2.6 Mean values of altitude, climate, and biomass for different grassland types during the past three decades (1982–2011)a Grassland type Meadow steppe Typical steppe Desert steppe Alpine steppe Montane steppe Marshy steppe Salt meadow Alpine meadow Warm tussocks Hot shrubby tussocks Temperate marsh Alpine marsh

MATb (
C) 3.30

MAPc (mm) 368.3

ABBd (g/m2) 281.1

RBe (g/m2) 1108.4

1461

4.82

299.7

138.7

654.7

2180 4777 1123

5.84 0.93 4.15

194.5 276.1 492.2

77.9 67.7 399.9

426.1 383.7 1441.7

749

2.61

449.3

405.8

1457.3

1154 4396

7.56 1.97

207.7 435.8

118.3 155.9

581.7 714.6

756

10.97

608.7

312.7

1199.2

986

17.92

1306.5

412.0

1473.5

531

0.87

480.8

513.5

1736.4

3610

2.14

626.4

361.8

1337.3

Elevation (m) 891

Note: aAdapted from Shen et al. (2016); bmean annual temperature; c mean annual precipitation; daboveground biomass; eroot biomass

of approximately 176 gC m2 yr.1 nationwide (Table 2.6). One can see from Fig. 2.2 that interannual variations were generally significant for almost all of the grasslands. However, they were much more substantial for some provinces and less significant for others.

2.5

Serious Degradation and Lowered Ecosystem Functions

Grassland degradation was alarmingly severe until the early 2000s when the nationwide campaign of livestock exclusion from grasslands commenced. Li (1997) estimated that, of the various grasslands in north China comprising a total area of about 2.7422  106 km2, roughly 50.24% 6 2 (1.3777  10 km ) was degraded to some extent. Among the degraded grasslands, 57.03% of the total area was assessed as lightly degraded, and 30.54% as intermediately degraded, with the remaining 12.16% being designated as heavily degraded as of 1995. A comparison to the relevant data from the early 1980s showed that the areas of degraded grasslands had increased considerably for most of the principal grassland regions, the overall ascending rate of which averaged to about 15,000 km2 per year (Liu and Diamond 2005). For example, during the period of 1980 to 1995, a year-by-year increase of 1.9% in the total area of degraded

Inner Mongolian grasslands was detected, amounting to an annual areal increase of 11,574 km2. Overgrazing has long been regarded as the most forceful factor engendering grassland degeneration in China. A metaanalysis based on 48 field studies including 251 datasets in the temperate steppes of north China showed that grazing had decreased the total biomass by 58.34%, increased the root/ shoot ratio by 30.58%, and decreased litter by 51.41%. Aboveground and belowground biomass decreased by 42.77% and 23.13%, respectively. However, biomass responses were dependent largely on the grazing intensity and site-specific environmental conditions. Percentage changes in aboveground biomass showed a quadratic relationship with precipitation in the lightly grazed pastures and a linear relationship in the moderately and heavily grazed pastures, but were insignificant with temperature. By contrast, grazing effects on belowground biomass were generally independent of precipitation or temperature regimes. Compared to the global average level, grazing had greater negative effects on the grassland production in China (Liang et al. 2013). Bai et al. (2012) conducted a field survey along a precipitation gradient across Inner Mongolian grasslands and found that long-term grazing had dramatically altered the C, N, and P pools and their stoichiometric relations within various steppe ecosystems. Grazing reduced the C, N, and P pool sizes in the aboveground biomass and litter, while the responses of belowground biomass and soil C, N, and P pools to grazing differed substantially among community types. Grazing increased N content and thus decreased the C:N ratio in the plant compartment, which accelerated N cycling to a great extent. The altered C:N:P stoichiometric ratios may be explained by changes in the composition of both plant species and functional groups as well as by increases in foliar N and P contents of the same species in grazed communities. Generally, the stoichiometric response to grazing was more considerable in the meadow steppe than in the typical steppe, while it was basically insignificant in the desert steppe.

2.6

Substantial Shrinkage of Within-Grassland Water Bodies

Within-grassland water bodies like interior rivers, lakes, streams, ponds, and “Nurs” (small ponds in the Mongolian language) and their riparian outstretches are crucial in maintaining the spatial distribution pattern of grassland vegetation and the biological diversity therein, and in facilitating matter exchanges between landscapes. Equally as important are the watering holes for livestock and wild animals. These watering holes determine to a large extent the utilization pattern and intensity of a grassland, as a grasslands’ feasibility and suitability as either grazing or mowing pastures

30

2 Overview of Chinese Grassland Ecosystems

Fig. 2.2 Changes in aboveground biomass of China’s grasslands during the period of 1982 to 2011. Solid line indicates that the temporal trend is statistically significant (p < 0.05). (Adapted from Shen et al. 2016)

depends heavily on the availability of and the distance from the watering hole in remote grasslands. Concerningly, Fang and his research team recently revealed substantial shrinkage in the water surface of the various water bodies and an obviously prolonged number of dry-up days in the rivers of Inner Mongolia’s broad grassland region, where many of the nation’s grassland interior rivers and major lakes are distributed. They detected the disappearance of a considerable number of small lakes and widespread grassland degradation on the Inner Mongolian Plateau in the past several

decades, with a particularly rapid loss of lakes since the late 1990s (Tao et al. 2015).

2.7

Rich Biodiversity of the Wildlife

China’s fauna is among the richest of the world. A total of some 6706 vertebrate species (including varieties or variants) have been recognized to range within the country, accounting for 14.8% of the world’s total. Of the vertebrate fauna, some

2.7 Rich Biodiversity of the Wildlife

31

607 mammalian, 1371 avian, 412 reptilian, 295 amphibian, and 4060 fish species have been recorded (Ma and Zhang 2009). Additionally, it has been established that 110 mammalian, 98 avian, 25 reptilian, and 30 amphibian species are endemic to China (NBEP 1998). Invertebrates (including insects) are too plentiful to realistically estimate. Wang and Zhang (1993a, b, c, d) listed 544 mammalian species of 211 genera distributed in 57 families under 14 orders that might be expected to have ranges in the various

Table 2.7 (continued) Order/family (34) Globicephalidae (35) Delphinidae (36) Phocoenidae (37) Physeteridae (38) Ziphiidae (39) Platanistidae 9 Carnivora (40) Canidae (41) Ursidae (42) Procyonidae (43) Ailuropodidae (44) Mustelidae (45) Viverridae (46) Felidae 10 Pinnipedia (47) Phocidae (48) Otariidae 11 Proboscidea (49) Elephantidae 12 Sirenia (50) Dugongidae 13 Perissodactyla (51) Equidae 14 Artiodactyla (52) Suidae (53) Camelidae (54) Tragulidae (55) Cervidae (56) Moschidae (57) Bovidae Total

Table 2.7 Statistics of different mammalian taxa occurring in Chinese grasslandsa Order/family 1 Insectivora (1) Erinaceidae (2) Soricidae (3) Talpidae 2 Scandentia (4) Tupaiidae 3 Chiroptera (5) Pteropodidae (6) Emballonuridae (7) Megadermatidae (8) Rhinolophidae (9) Molossidae (10) Vespertilionidae 4 Primates (11) Lorisidae (12) Cercopithecidae (13) Hylobatidae 5 Pholidota (14) Manidae 6 Lagomorpha (15) Leporidae (16) Ochotonidae 7 Rodentia (17) Petauristidae (18) Sciuridae (19) Castoridae (20) Hystricidae (21) Caviidae (22) Zapodidae (23) Dipodidae (24) Muscardinidae (25) Platacanthomyidae (26) Rhizomyidae (27) Muridae (28) Cricetidae (29) Chinchillidae (30) Capromyidae 8 Cetacea (31) Balaenopteridae (32) Balaenidae (33) Eschrichtiidae

Genus 22 5 10 7 1 1 29 5 1 1 4 2 16 6 1 4 1 1 1 2 1 1 65 7 11 1 2 1 2 7 2 1 1 11 17 1 1 21 2 1 1

Species 59 7 41 11 1 1 105 7 2 1 22 2 71 20 2 14 4 2 2 30 9 21 181 18 27 1 4 1 3 11 2 1 3 40 68 1 1 31 6 1 1 (continued)

a

Genus 3 8 1 2 2 1 33 4 3 1 1 9 9 6 4 2 2 1 1 1 1 1 1 24 1 1 1 8 1 12 211

Species 3 13 1 2 3 1 58 6 4 1 1 21 12 13 5 3 2 1 1 1 1 3 3 47 2 1 1 17 6 20 544

After Wang and Zhang (1993a, b, c, d)

terrestrial ecosystems of China. A look at the list reveals that about 60% of the species have ranges fully or partially in the various rangelands nationwide (Table 2.7). Some 1371 species of birds have been recorded in China, belonging to 439 genera and 101 families within 24 orders (Zheng 2011). Zoogeographically, China’s avifauna belongs to two biogeographic realms, i.e., the Paleoarctic realm and the Oriental realm, which are generally divided by the Qinling Mountains. Of the zoogeographical subregions, the southwest mountainous subregion contains the highest species richness, whereas the Qiangtang Plateau subregion of north Tibet has the least species richness. In recent decades, obvious increases in the richness of birds within different subregions have been reported. It was estimated that the average number of species per subregion grew from 232 in 1976 to 281 in 2005 (Wang et al. 2010). When it comes to Chinese grasslands or rangelands, increases in the species richness of Aves were most significantly detected in the eastern grassland subregion, the Qiangtang Plateau

32

2 Overview of Chinese Grassland Ecosystems

Table 2.8 Changes in the spatial and temporal patterns of the bird species richness in 16 avifaunal subregionsa Sequence number 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 a

Avifaunal subregion Greater Hinggan Mountains Changbai Mountains Huanghuaihai plain Loess Plateau Eastern grassland Western desert Tianshan Mountains Qiangtang Plateau Qinghai & southern Tibet Southwest mountain areas Eastern hilly areas & plains Western montane plateaus Fujian-Guangdong coasts Southern Yunnan mountains Hainan Islands Taiwan Islands

No. of spp. in 1976 201

No. of spp. in 2005 217

Increase in species no. to 2005 43

Decrease in species no. to 2005 27

Extent of net change (%) 16.92

227 146 207 156 218 219 77 237

261 191 289 246 287 251 108 299

38 59 117 106 92 48 52 100

4 14 36 16 23 16 21 39

16.74 40.41 56.52 67.95 42.20 21.92 67.53 42.19

519

554

90

55

17.34

233

262

54

25

23.18

295

343

81

32

27.46

240

306

92

26

38.33

371

501

144

14

38.31

198 169

199 179

15 19

14 9

4.04 11.83

After Wang et al. (2010)

subregion, and the western desert subregion in terms of the proportional degree (Table 2.8). These increases are generally attributed to changes in three aspects, i.e., human disturbances that lead to the upward distribution of birds on the higher mountains (Yao 1991), shrinkage in lake water surfaces which engenders significant extensions of marshes and marshy meadows such as those dominated by reeds and sedges commonly occurring in the desert steppe and typical steppe regions of Inner Mongolia (Pan et al. 2006), and climate change, which leads to the frequent and longer-staying migrations of the transient species further northward (Sun and Zhang 2000). The fauna of the grassland regions of China is also considerably rich and diverse. Zoogeographically, the grassland fauna belongs to the Inner Mongolia-Xinjiang division and the Qinghai-Tibet division of the Central Asian sub-realm under the Paleoarctic realm. A conservative estimation showed that at least 60 amphibian, 100 reptilian, 500 avian, and 300 mammalian species are the permanent or seasonal residents of the various grassland ecosystems of China. The number and composition of the wild animal species in each major grassland province are shown in Table 2.9. The grassland fauna consists mainly of the Central Asian and the Boreal elements, characterized by an extreme lack of amphibian species; reptiles are dominated primarily by the suborder Lacertilia (formerly the order Sauria), while mammals consist mainly of rodents and ungulates. Melanocorypha spp. (lark), Pterocles spp. (sand-grouse),

Table 2.9 Species number and province-based distribution of the major terrestrial vertebrate taxa in Chinese grassland ecosystemsa Province Inner Mongolia Xinjiang Ningxia Gansu Tibet Qinghai

Amphibianb 2–5-9 2–3-6 1–3-7 2–4-6 2–5-45 2–5-9

Reptile 3–7-28 4–7-43 4–8-21 1–1-4 1–7-55 2–5-7

Bird 18–61–436 17–55-398 18–64-286 8–14-41 19–64-488 16–39-293

Mammal 7–20-138 7–22-136 6–19-77 5–12-41 8–21-142 8–23-103

Note: aSummarized according to Ma and Zhang (2009); bthe numbers are arranged in the order-family-species sequence in each row

Podoces spp. (ground-Jay), Montifringilla spp. (snow finch), and Syrrhaptes spp. are eurytopic avian species found mostly in the various grassland habitats of north China as well as in the Qinghai-Tibet region (Table 2.10) (Ma and Zhang 2009). In the Inner Mongolia-Xinjiang division, animal species are characterized by their strong adaptabilities to the dry, hot, highly variable summer climate as well as to the desert and grassland food-supplying conditions. Important ungulates in this division include Equus spp., Camelus ferus, Budorcas taxicolor, Procapra gutturosa, Capreolus capreolus, Capra ibex, Gazella subgutturosa, Naemorhaedus caudatus, Ovis ammon, and Cervus elaphus. Carnivorous animals consist predominantly of a few species such as Vulpes spp., Martes

2.8 Rampant Rodent and Insect Outbreaks

33

Table 2.10 Important avian and mammalian species, their population sizes, and major biotopes in Chinese grassland ecosystemsa Species Avian species Gypaetus barbatus Falco tinnunculus Tetraogallus tibetanus Crossoptilon auritum Melanocorypha mongolica Mammals Canis lupus Vulpes vulpes V. corsac Ursus arctos Panthera uncia Equus hemionus E. kiangc Camelus ferus Moschus chrysogaster M. leucogaster Cervus albirostris C. elaphus Alces alces Capreolus capreolus Bos mutus Procapra picticaudata P. gutturosa Gazella subgutturosa Pantholops hodgsoni Budorcas taxicolor Capra ibex Pseudois nayaur Ovis ammon Marmota baibacina M. himalayana M. caudata

Pop. size (indiv.)

Area (km2)

Habitat

Distributionb

91,161 578,831 375,850 75,000 5,182,200

837,163 2,263,967 697,493 13,378 362,974

Steppe, rocky land Des. steppe, hills, alp. meadow Rocky land, alp. meadow/steppe Mont. Meadow, shrubby tussock Typic. steppe, des. Stepp, Agro-past.

Q, X, G, T X, I, G, T T, Q, X, G G, Q, I, N I

29,100 99,700 160,000 11,050 2580 14,000 109,500 380 27,300 3000 37,000 89,000 6500 351,800 27,000 280,000 8000 190,000 130,000 22,000 51,000 460,000 64,000 350,000 370,000 30,000

1,734,300 2,093,183 1,648,029 1,345,586 696,262 798,195 464,755 606,186 Not avail. 3300 Not avail. Not avail. 200,000 675,762 Not avail. Not avail. 155,959 1,763,573 Not avail. Tot avail. 726,700 Not avail. Not avail. 302,813 Not avail. 489,863

Alp. meadow, steppe, desert, hills Steppe, desert, hills, alp. grassland Steppe, shrubby desert, meadow Meadow, steppe, desert Forest, alp. grassland, shrubland Arid, semiarid, and steppic desert Alpine steppe, des. steppe, and desert Desert, gobi, sandland Montane shruby land, alpine meadow Alp. shrubby land, shrubby meadow Alp. des-., meadow-, shrubby-steppe, Forest, shrubby grassland, des. steppe Secon. forest, shrubby tussock Secon. Forest, shrubby tussock Alp. meadow, steppe, desert, piedm. Alp. subalp. meadow, steppe, desert Typical and des. Steppe Desert stepp, desert, gobi Alp. meadow, steppe, desert Forest Mon. steppe, rocky land, grav. land Bare rocky, grassy and shrubby land Desert steppe and alp.meadow steppe Mont. steppe, meadow Mont. Meadow, steppe, shrub tussock Mont. steppe, meadow

Q, X, G, T I, Q, X, T, G, N I, X, N, G Q, T, X, I, G X, T, Q, G, I X, G, N Q, X, G X, I T, Q, S, G, I, N T Q, T, S, G X, T, G, Q I I, H, G, X, Q, N Q, T, X, G T. Q, X, G, S G, I, N X, G, Q, I, N T, X, Q G, S, Sha, T, Y X, G, I Q, T, X, I, G, N, X, G, T, Q, N X S, X, Q, G X

Note: aBased on the data collected in the 1995-2005 National Survey of the Terrestrial Wild Animals in China (Ma and Zhang 2009); bT, I, X, Q, G, N, S, Y, and Sha. are abbreviations for Tibet, Inner Mongolia, Xinjiang, Qinghai, Gansu, Ningxia, Sichuan, Yunnan, and Shaanxi, respectively; c 57,000 head in Tibet and 3500 head in Sichuan are not included because data for those areas are not available

zibellina, and Mustela sibirica. Phrynocephalus spp. (about 13 species) and Eremias spp. are the most prominent reptiles. Amphibian species are extremely rare in the grasslands, primarily consisting of several Bufo species. In the QinghaiTibetan division, a large portion of the wild animals are endemic to the plateau environments. The most important grassland herbivores are Equus kiang, several Moschus spp., Cervus albirostris, Bos mutus, Pantholops hodgsoni, and Pseudois nayaur. Important avian species include Gypaetus barbatus, Tetraogallus tibetanus, Tetraophasis obscurus, Lerwa lerwa, Crossoptilon crossoptilon, Melanocorypha maxima, and Montifringilla species. In addition, some 20 amphibian species in the family Pelobatidae are found in the alpine meadow and the meadow steppe, and five Phrynocephalus (sand lizard) species range in the alpine

desert of Tibet, while Altirana parkeri, an important amphibian species, occurs in the middle reaches of the Yarlung Zangbo River.

2.8

Rampant Rodent and Insect Outbreaks

The northwestern half of China as demarcated by the Hu Huanyong Divide contains the bulk of Chinese grasslands and rangelands. It lies between 73
400 E and 123
400 E and roughly between 28
N and 50
N, including the entirety of Xinjiang, nearly all of Inner Mongolia, much of Tibet, Qinghai, Gansu, and Ningxia, and portions of Shaanxi, Shanxi, Hebei, Henan, Liaoning, and Jilin (CPGCAS 1985).

34

2 Overview of Chinese Grassland Ecosystems

Table 2.11 Distribution of Glires among nine grid groups of the Chinese arid regiona Species 1. Lepus timidus 2. L. capensis 3. L. oiostolus 4. L. yarkandensis 5. Ochotona alpina 6. O. argentata 7. O. daurica 8. O. hyberborea 9. O. roylei 10. O. curzoniae 11. O. pallasi 12. O. macrotis 13. O. ladacensis 14. O. erythrotis 15. O. koslowi 16. O. cansus 17. O. huangensis 18. O. nubrica 19. O. himalayana 20. O. thomasi 21. O. iliensis 22. Sciurus vulgaris 23. Marmota himalayana 24. M. baibacina 25. M. caudate 26. M. sibirica 27. Spermophilus undulates 28. S. erythrogenys 29. S. dauricus 30. S. relictus 31. Eutamias sibiricus 32. Dremomys lokriah 33. Petaurista magnificus 34. Petaurista xanthotis 35. Pteromys volans 36. Castor fiber 37. Cricetus cricetus 38. Cricetulus migratorius 39. C. barabensis 40. C. eversmanni 41. C. longicaudatus 42. C. triton 43. C. kamensis 44. C. curtatus 45. Phodopus songorus 46. Ph. roborovskii 47. Myospalax aspalax 48. M. psilurus 49. M. fontanieri 50. M. cansus 51. M. baileyi 52. Microtus agrestris

Frequency of species occurring in each grid groupb (%) IAa IAb IBa IBb IIA 0.13 0 0 0.02 0 1.00 1.00 0.03 0.63 0.64 0 0 0.96 0.07 1.00 0 0 0.02 0.41 0 0 0 0 0 0 0 0.07 0 0 0 0.84 1.00 0.05 0 0.91 0.03 0 0 0 0 0 0 0.04 0 0 0 0 0.77 0 1.00 0 0.24 0 0.03 0 0 0 0.89 0.09 1.00 0 0 0.46 0.06 0 0 0 0.18 0 1.00 0 0 0.01 0 0 0 0.09 0.07 0 1.00 0 0 0 0 1.00 0 0 0.11 0 0 0 0 0.04 0 0 0 0 0.05 0 1.00 0 0 0 0.03 0 0.07 0 0 0 0 0 0 0.73 0.09 1.00 0 0 0 0.11 0 0 0 0.06 0.03 0 0.58 0.06 0 0 0 0 0 0 0.01 0 0 0.36 0 0.11 0 1.00 0.97 0 0.02 0.64 0 0 0 0 0 0.72 0.57 0 0 0.82 0 0 0.02 0 0 0 0 0.03 0 0 0 0 0.02 0 1.00 0.38 0 0 0 0.18 0 0 0 0 0 0 0 0 0 0 0 0.63 0.26 0.88 0.09 1.00 0.99 0 0.03 0.27 0 0 0 0 0 0.17 0.46 0.26 0.13 1.00 0.30 0.20 0 0 0 0 0 0.55 0 0.91 0.15 0.83 0 0.17 0 0.85 0.66 0 0 0 0.56 1.00 0.19 0.27 0.45 0.83 0.10 0 0 0 0.31 0 0 0 0 0.03 0.36 0 0 0 0 0.04 0 0 0.36 0 0 0.10 0.02 1.00 0 0 0 0 0

IIB 0 1.00 0.90 0 0 0.10 0 0 0 0.60 0 1.00 0 0.90 0 0.70 0.70 0 0 0.70 0 0 1.00 0 0 0 0 0 0.70 0 0.30 0 0 0.80 0.10 0 0 1.00 0.08 0 1.00 0 0.50 0.20 0 0.80 0 0 0 0 1.00 0

IIIA 0.93 1.00 0 0 0.93 0 0 0 0 0 0.13 0 0 0 0 0 0 0 0 0 0 0.93 0 0.93 0 0 1.00 0.53 0 0 0.93 0 0 0 0.93 0.13 0.20 1.00 0 0.33 0.93 0 0 0 0 0.20 0 0 0 0 0 0.13

IIIBa 0.13 1.00 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.93 0 0 0.07 1.00 0 0 0 0 0 0 0 0 0.60 1.00 0 0.40 1.00 0 0 0 0 0.27 0 0 0 0 0 0.07

IIIBb 0 1.00 0 0 0 0 0 0 0 0 0 0.08 0 0 0 0 0 0 0 0 0.62 0 0 0.96 0 0 0.69 0.04 0 0.50 0 0 0 0 0 0 0 1.00 0 0 0 0 0 0 0 0 0 0 0 0 0 0 (continued)

2.8 Rampant Rodent and Insect Outbreaks

35

Table 2.11 (continued) Species 53. M. socialis 54. M. oeconomus 55. M. arvalis 56. M. gregalis 57. M. maximowiczii 58. M. brandti 59. M. mandarinus 60. M. fortis 61. M. fuscus 62. M. ilaeus 63. M. mongolicus 64. Arvicola terrestris 65. Ellobius talpinus 66. Pitymys sikimensis 67. P. leucurus 68. P. juldaschi 69. P. irene 70. Clethrionomys rutilus 71. C. rufocanus 72. C. centralis 73. C. frater 74. Lagurus lagurus 75. L. luteus 76. L. rzewalskii 77. lticola roylei 78. A. macrotis 79. A. stoliczkanus 80. A. stracheyi 81. A. strelzowi 82. A. semicanus 83. A. barakshin 84. Caryomys eva 85. Meriones tamariscinus 86. M. meridianus 87. M. libycus 88. M. unguiculatus 89. M. chengi 90. Rhombomys opimus 91. Brachiones przewalskii 92. Mus musculus 93. Rattus norvegicus 94. R. nitidus 95. R. rattoides 96. Rattus flavipectus 97. Apodemus sylvaticus 98. A. agrarius 99. A. peninsulae 100. Nesokia indica 101. Niviventer confucianus 102. N. fulvescens 103. N. eha 104. Dryomys nitedula

Frequency of species occurring in each grid groupb (%) IAa IAb IBa IBb IIA 0 0 0 0.03 0 0 0 0.11 0.09 1.00 0 0 0 0.03 0 0.69 0 0 0.10 0 0.72 0 0 0 0 0.80 0.20 0 0 0 0.47 0.31 0 0 0 0 0.23 0 0 0 0 0 0.13 0 0 0 0 0 0 0 0.17 0 0 0 0 0 0 0 0 0 0.08 0.60 0 0.17 0.27 0 0 0.03 0 0 0 0 0.82 0.07 0 0 0 0.05 0.03 0 0 0 0.08 0 1.00 0.06 0 0 0 0 0.73 0.20 0 0 0 0 0 0 0 0 0 0 0 0.02 0 0 0 0 0.10 0 0 0 0 0.12 0 0 0.47 0.05 0.09 0 0 0 0 0.12 0 0 0 0 0 0 0 0 0.32 0 0 0 0 0.10 0 0.45 0 0 0 0 0 0.09 0.10 0 0 0 0 0 0 0.02 0 0 0 0 0 0.09 0 0 0 0.25 0 0.28 1.00 0.19 1.00 0.36 0 0 0 0.07 0 0.92 1.00 0 0.02 0.27 0 0 0 0.01 0 0 0.34 0.01 0.48 0 0 0 0 0.42 0 1.00 1.00 0.63 0.95 1.00 1.00 0.99 0 0 0.73 0 0 0.01 0 0 0 0 0.04 0 0 0 0.01 0.01 0 0 0 0 0.04 0.47 0 0.53 0.03 0 0 0 0.40 0.11 0.01 0 0.91 0 0 0 0.40 0 0.14 0.39 0 0 0 0 0 0.02 0 0 0 0 0.04 0 0 0 0 0 0.01 0

IIB 0 1.00 0 0 0 0 0 0 0 0 0 0 0.90 0 0 0 0.50 0 0 0 0 0 0 0.40 0 0 0 1.00 0 0 0 0 0.20 1.00 0 1.00 0 0.90 0.10 1.00 0 0 0 0 0 0 0.10 0 0 0 0 0

IIIA 0 1.00 1.00 1.00 0 0 0 0 0 0 0 0.07 0.93 0 0 0 0 0.87 0.80 0 0 0 0.67 0 0 0.87 0 0 0.87 0 0 0 0.53 0.40 0 0 0 0.13 0 1.00 0 0 0 0 0.87 0 0.20 0 0 0 0 0.60

IIIBa 0.80 0.73 0.93 0.93 0 0 0 0 0 0.07 0 0.60 1.00 0 0 0 0 0 0 0 0 0.73 1.00 0 0.80 0 0 0 0.27 0 0 0 0.93 0.93 0.40 0 0 0.40 0 1.00 0 0 0 0 1.00 0.27 0 0 0 0 0 0.20

IIIBb 0.38 0.58 0 0.96 0 0 0 0 0 0.73 0 0.15 1.00 0 0 0 0 0 0 0.23 0.92 0.65 0.50 0 0.88 0 0 0 0 0 0 0 0.77 0.65 0.50 0 0.12 0.31 0 1.00 0 0 0 0 1.00 0 0 0.08 0 0 0 0.58 (continued)

36

2 Overview of Chinese Grassland Ecosystems

Table 2.11 (continued) Species 105. Sicista subtilis 106. S. concolor 107. Eozapus setchuanus 108. Dipus sagitta 109. Scirtopoda telum 110. S. andrewsi 111. Allactaga sibirica 112. A. elater 113. A. bullata 114. Alactagulus pygmoeus 115. Euchoreutes naso 116. Cardiocranius paradoxus 117. Salpingotus kozlovi 118. S. crassicauda 119. Hystrix hodgsoni

Frequency of species occurring in each grid groupb (%) IAa IAb IBa IBb IIA 0 0 0 0 0 0 0 0.01 0.06 1.00 0 0 0.04 0 1.00 0.58 0.91 0.13 0.93 0 0 0 0 0.06 0 0 0.67 0 0.02 0 0.99 1.00 0.24 0.57 0.82 0 0 0 0.12 0 0 0.66 0.01 0.32 0 0 0.16 0 0.33 0 0 0.19 0.17 0.91 0.09 0 0.71 0.01 0.24 0.09 0 0.57 0.01 0.87 0 0 0.13 0 0.33 0 0 0 0.02 0 0

IIB 0 1.00 0.20 0.80 0 0.20 1.00 0 0.60 0 0.90 1.00 0.60 0.10 0

IIIA 0 0 0 0.40 0.07 0 0.60 0.40 0 0.27 0 0 0 0.27 0

IIIBa 0.40 0.73 0 0.87 0.53 0 1.00 0.87 0 0.40 0 0.13 0 0.40 0

IIIBb 0 0.96 0 0.65 0 0 0.54 0.65 0 0.35 0.12 0 0.08 0.19 0

Note: aAfter Zhou et al. (2002); bAbbreviations for the names of grid groups are IAa the meadow steppe and typical steppe zone involving the eastern Inner Mongolia Plateau, the Greater Hinggan Mountains, and their neighboring regions; IAb desert steppes in Ningxia, the Helan Mountains, the central Inner Mongolia Plateau, and the Ordos Plateau; IBa the entire Qinghai-Tibet Plateau except for the Qilian Mountains but with the Pamir Plateau; IBb temperate deserts from Alxa through the Tarim Basin and the Junggar Basin; IIA east of the Qilian Mountains; IIB north slopes and piedmont plains of the Qilian Mountains; IIIA the Altay Mountains and its southern piedmont plains; IIIBa Emin Valleys and the surrounding mountains and piedmont plains of the Junggar Basin; IIIBb the Tianshan Mountains as well as Ili valleys

Zhou et al. (2002) reported that about 119 species of Glires (including Lagomorpha and Rodentia) have ranges in the various ecosystems throughout this northwestern half, of which three distributional regions are recognized, including 9 divisions (Table 2.11). Generally, the distribution of Rodentia in the lower-altitude arid regions of China is characterized by gradual increases in the xerophilous species and decreases in the hygrophilous ones with increasing aridity, which is in accordance with the mutual replacements of vegetation types from steppe to semidesert, true desert, and up to the extremely dry desert. The species composition of rodents in the frigid alpine desert regions of the QinghaiTibet Plateau and the Pamir Plateau is closely linked to that of the warm and warmer desert regions, featured by significantly lower species diversity. Rodentia on the Altay Mountains and the plains to its south contains more hypothermophilous-hygrophilous species. Rodentia of the Tianshan Mountains, Ili valleys, piedmonts around the Junggar basin, and the Qilian Mountains are rather complicated and species-rich. Transitional regions from the steppe to the desert generally contain much more diverse species. In addition, there are clues evidencing that the Inner MongoliaXinjiang desert division and the Qinghai-Tibet alpine desert division have certain historical connections in terms of the origin and evolution of rodent species (Zhou et al. 2002). In addition, to the south of the lower reaches of the Yangtze

River, at least 85 species of Glires have ranges in various ecosystems (Table 2.12) (Qin 1983). Rodents comprise the majority of small mammals and permanent residents of grasslands, which play an indispensible role in the matter cycling and energy flow of those ecosystems, as well as in influencing the biodiversity, structure, and functioning of grassland ecosystems both favorably and unfavorably. Their harmful effects on grasslands are characterized primarily by nibbling forage plants both above- and belowground in an undesired way, digging holes and passages underground, and dispersing contagious diseases to wildlife and livestock. As far as Chinese temperate grassland ecosystems are concerned, about 80 species of rodents are commonly found therein (Li and Li 1996), which are dominated mainly by species of the family Dipodidae such as Allactaga sibirica, Dipus sagitta, and Euchoreutes naso, species of Gerbillidae such as Rhombomys opimus, Meriones unguiculatus, and M. meridianus, and a few species of Sciuridae such as Marmota baibacina and M. caudata, especially in the Inner MongoliaXinjiang faunal division. In contrast, those ranging in the Qinghai-Tibet faunal division are dominated overwhelmingly by species of the family Ochotonidae. Myospalax fontanieri and Allactaga sibirica occur ubiquitously in the various grasslands across the country. In the temperate grasslands, most principal species include Microtus spp., Myospalax

2.8 Rampant Rodent and Insect Outbreaks

37

Table 2.12 Rodent species and their distributions in southern Chinaa No 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52

Species Lepus capensis L. sinensis L. hainanus L. oiostolus Ochotona thibetana O. sp. O. cansus O. brookei O. gloveri O. macrotis O. daurica O. erythrotis O. roylei Belomys pearsonii Trogopterus xanthipes Petaurista petaurista P. punctatus P. yunnanensis P. hainana P. alborufus P. clarkei Aeretes melanopterus Hylopetes alboniger Pteromys volans Callosciurus erythraeus C. flavimanus C. pygerythrus C. quinquestriatus Tamiops macclellandi T. swinhoei Dremomys lokriah D. pernyi D. rufigenis Ratufa bicolor Menetes berdmorei Sciurotamias davidianus S. forresti Eutamias sibiricus Marmota himalayana Atherurus macrourus Hystrix hodgsoni Typhlomys cinereus Rhizomys sinensis Rh. pruinosus Rh. sumatrensis Rh. (Cannomys) badius Vernaya foramena Hapalomys longicaudatus Chiropodomys gliroides Micromys minutus Mus musculus Mus sp.

Provinceb GD GX + +

+

FJ

YN

+

+ + +

GZ + +

SC + +

HN + +

JX + +

+

+ + + +

+ +

+ +

+

+ + + +

+ +

+

+

+

+

+

+

+

+ +

+ +

+

+

+

+

+

+ +

+

+

+ +

+ +

+ +

+ +

+ +

+ + +

+ + + +

+ +

+

+

+ + + + +

+ + +

+ +

+

+

+ + +

+

+ + +

+

+ +

+

+

+

+ +

+ + +

+ +

+ + + +

+ + + +

+ + + +

+ + + + + + + + + + + + + + + + + + + +

+ + + + +

+

+ + + + +

+ + +

+ +

+ + +

+ +

+ +

Faunal elementc C O O C P P P P P P P P P O O O O O O O O O O O O O O O O O O O O O O P P P P O O O O O O O P O O P C O (continued)

38

2 Overview of Chinese Grassland Ecosystems

Table 2.12 (continued) No 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85

Species Mus pahari Apodemus syhaticus A. peninsulae A. agrarius A. chevrieri A. flavicollis A. latronum Rattus rattus R. flavipectus R. eha R. nitidus R. rattoides R. norvegicus R. fulvescens R. confucianus R. exulans R. sp. R. coxingi R. bowersi R. cremoriventer Bandicota indica Unidentified sp. Myospalax fontanieri Clethrionomys rufocanus Eothenomys melanogaster E. miletus E. proditor E. sp. E. eleusis Microtus fortis Pitymys irene Proedromys bedfordi Sicista concolor Total

Provinceb GD GX

FJ

+ +

SC + + + + +

+ + + + + + + + +

+ + + + + + + + +

+

+ + +

+

+

+

+

+ + + + +

+ +

+ + + + + + + + + + + + +

+

+

+ + +

+ +

+ +

+ +

+ + + + + + +

+ + + + +

+ + + + +

+

+

+

+ + +

+

+

+

+

+

YN + + + + + + + + + + + + + + +

GZ + +

+

+

+ +

+

32

28

28

+ 62

41

HN

JX

+ + +

+

+ +

+ +

+ + + + +

+ + + + +

+ + +

+ + +

+

+

+

+

+ + + + 58

31

Faunal elementc O P P P P P P O O O O O C O O O O O O O O O P P P P P P P P P P P

27

Note: aAfter Qin (1983); bGD Guangdong, GX Guangxi, FJ Fujian, YN Yunnan, GZ Guizhou, SC Sichuan, HN Hunan, JX Jiangxi; cO Oriental, P Palaearctic, C cosmopolitan

spp., Lepus spp., Ochotona daurica, Citellus dauricus, Marmota sibirica, Cricetulus barabensis, and Meriones spp.; in the steppic desert and temperate desert, Lepus yarkandensis, Ochotona pallasi, Citellus spp., Rhombomys opimus, Meriones spp., Lagurus spp., Microtus mandarinus, Dipus sagitta, and Stylodipus telum are most abundant; in the montane steppe and meadow, Ochotona pallasi, Marmota caudata, Citellus spp., Cricetulus barabensis, Lagurus lagurus, and Microtus gregalis are most prominent; found most frequently in the alpine steppes are Lepus oiostolus, Marmota himalayana, Pitymys irene, and Ochotona spp. (Li and Li 1996). Marmota himalayana is a dominant rodent in the Aba and Ganzi grasslands of western Sichuan. Statistical data show that on average some 170,000 km2 of grasslands suffered significant rat infestations per annum

during the 1990s, the most severe period in China, during which the affected area in each of the provinces of Inner Mongolia, Gansu, Qinghai, and Sichuan exceeded 20,000 km2. Sichuan was one of the most badly infested provinces, with the density of rat holes dug by Microtus brandti and Ochotona curzoniae reaching 3000 per hectare in some areas, and 650 soil mounds per hectare unearthed by Myospalax species. By contrast, the total area infested by rodents averaged roughly 385,400 km2 nationwide during the period of 2003–2012, accounting for nearly one-tenth of the nation’s total grassland area (Hong et al. 2014). However, a gradually decreasing trend is also obvious during this decade, with a yearly reduction rate of 7.8% observed in the affected area. Nevertheless, the decadal mean area affected is still 0.2 million km2 more than the level 20 years ago, although

2.8 Rampant Rodent and Insect Outbreaks

39

Table 2.13 Rat-affected areas (km2) in major grassland regions and in the country as a whole between 2006 and 2011a Province Inn. Mongolia Xinjiang Gansu Sichuan Tibet Qinghai Nationwidec

2006 85,770 41,060 54,400 28,630 15,950 95,150 374,900

2007 69,930 51,930 57,270 28,630 49,110 84,330 389,400

2008 72,290 39,250 55,690 28,830 56,670 67,230 367,580

2009 80,800 55,640 53,630 28,570 58,000 86,720 408,720

2010 65,480 57,840 52,730 29,180 59,330 80,720 386,780

2011 60,340 57,660 49,850 30,810 68,770 83,330 387,240

Aver. 72,435 50,563 53,928 29,108 51,305 82,913 385,770

Prop.(%)b 9.2 8.8 30.1 12.9 6.3 22.8 9.8

Note: aAdapted from CMA (2013); bproportion of the affected area in the total grassland area of the province; calso including those in Hebei, Shanxi, Shaanxi, Heilongjiang, Jilin, Liaoning and Ningxia

intensive eradication programs have been continually implemented in various grasslands. In total, more than 100 rodent species are recognized as pest species, of which 20 or so are the most common and injurious, including Ochotona curzoniae, Myospalax baileyi, Rhombomys opimus, Meriones unguiculatus, Lagurus luteus, Microtus brandti, Spermophilus dauricus, Spermophilus erythrogenys, Myospalax psilurus, Myospalax aspalax, and Ellobius talpinus. From 2006 to 2013, roughly one-tenth of the total grassland area nationwide had been subject to rat damages (Table 2.13). Insects are also important as a consumer group and extremely critical to plant pollination in various terrestrial ecosystems. It was speculated that the nation’s total number of insect species might attain 150,000, provided that 1/10 of the world’s total insect species occur in China (NBEP 1998). Realistically speaking, this estimate in all probability is a bit conservative. According to the data on several wellinvestigated large insect groups, the relevant proportions they account for are far greater than 1/10. For example, the total number of confirmed species in the general families Aphidoidea and Adelgoidea found in China (some 1000 species) amount to 25% of the world’s total recorded (roughly 4000 species); the total species in Muscidae, Siphonaptera, and Tachinidae occurring in China account for 23.1%, 19.9%, and 16.7%, respectively, of the relevant total numbers of the species in these same families worldwide. As of 1997, some 51,000 insect species had been identified and recorded in China, increasing at a rate of 500 newly recognized species annually in the prior two decades (NBEP 1998). A considerable number of the nation’s endemic insect species occur in the grassland regions. For instance, in the Qinghai-Tibet faunal division, some 200 insect species in the suborder Acridodea have been recorded, of which more than half are endemic to the mega-region; a total of 62 species in the family Hepialidae have been identified in China, among which 41 are endemic to this region; 93 species of Leptomias in the family Curculionidae have been recorded worldwide, while 55 of them are Tibet-endemic. Quite the same pattern

exists for the Inner Mongolia-Xinjiang faunal division. Out of the 11 genera of the family Pamphagidae found in China, 10 genera are native to northwest China, with 5 genera Xinjiang-endemic; among the 75 species of Sphingonotus in the family Oedipodidae recorded in the world, 33 are found in China, with 14 species endemic to Xinjiang (NBEP 1998). At a local scale, insect species are apparently more numerous in grasslands than in the adjacent habitats of other ecosystems such as croplands and forests. For example, in an alpine meadow grassland with an area of some 1500 km2 in Qinghai, 374 insect species belonging to 126 families and 11 orders were observed at various habitats, whereas in the adjacent croplands cultivated over two decades, only 75 species of 37 families were found (Wu and Jin 1982). In a steppe within the Xilin River Basin with an area of about 10,000 km2, as many as 33 species of the family Acrididae, belonging to 24 genera and 4 subfamilies, were identified (Li and Chen 1988). A total of 144 species of grasshoppers belonging to 51 genera and 7 families have been recorded in northeast China (Xing et al. 2005). Of these, the Palaearctic species are most numerous, making up 87.85% of the total species number, including Euchorthippus zuojianus, Oxya velox, Chorthippus hammarstroemi, Parapleurus alliaceus, E. longipennis, and Omocestus haemorrhoidalis; the oriental species include Atractomorpha peregrine, A. heteroptera, Ch. aethalinus, and Acrida lineata; the widely distributed species include Haplotropis brunneriana, Atractomorpha lata, Calliptamus abbreviatus, Oxya chinensis, and Bryodemella tuberculatum dilutum; native to the region are Primnoa spp., Zubovskia brachycercata, Liaoacris ochropteris, Anapodisma rufupenna, and Chrysacris changbaishanensis (Sun et al. 2006). Some 24 species are found in the meadow steppe, while others occur mainly in the sandlands, montane shrubby grasslands, and woodlands, as well as croplands of the region. About 360 species (subspecies) of Tenebrionid beetles in the order Coleoptera are documented to occur in various terrestrial ecosystems of the Mongolia Plateau, belonging to

40

2 Overview of Chinese Grassland Ecosystems

Table 2.14 Insect-affected areas (km2) in major grassland regions and in the country as a whole between 2006 and 2011 in Chinaa Province Inn. Mongolia Xinjiang Gansu Sichuan Tibet Qinghai Nationwidec

2006 68,130 29,100 15,440 9180 1090 15,900 168,300

2007 74,580 26,170 14,710 8570 3120 16,620 175,800

2008 150,470 31,120 14,930 8580 4370 25,600 270,070

2009 88,780 28,400 13,640 8150 2100 21,960 207,620

2010 79,630 27,000 13,430 8100 1970 18,020 180,670

2011 74,770 29,610 14,660 8270 360 16,640 176,580

Aver. 89,393 28,567 14,468 8475 2168 19,123 196,507

Prop.b 11.3 5.0 8.1 3.8 0.3 5.3 5.0

Note: aAdapted from CMA (2013); bproportion of the affected area in the total grassland area of the province; calso including those in provinces Hebei, Shanxi, Shaanxi, Heilongjiang, Jilin, Liaoning, and Ningxia Hui Nationality Autonomous Region

82 genera, 30 tribes and 6 subfamilies (Sun 2016). Subfamilies of Tenebrioninae (154 spp.) and Pimeliinae (159 spp.) contain the most species, which together account for about 86.94% of the total species number of the family; by contrast, subfamilies Lagriinae, Diaperinae, Alleculinae, and Stenochiinae are rather species-poor, each containing 8, 16, 20, and 3 species, respectively. At the tribe level, Tentyriini and Opatrini have the most species, each containing 123 and 94, respectively. Overall, 42 genera are monotypic, 23 having just 2–5 species. In addition, 5 genera and 101 species are endemic to the Mongolian Plateau. Zoogeographically, the Palaearctic species account for 74.17%, and the north China-Oriental species account for 13.61%, whereas the worldwide species make up less than 3% of the total species in this vast zone. Generally, the three most concentrated distribution areas are distinctively recognized, i.e., the Gobi-Altay desert, the Altay mountain areas, and the Helan mountain areas. Insect damage to grassland ecosystems has long been one of the most severe environmental and animal husbandryimpairing problems in China. Locusts (Acridoidea) are the most widely distributed pest insect group in China. Major species include Locusta migratoria, Myrmeleotettix palpalis, Calliptamus italicus, Comphocerus sibiricus, Haplotropis brunneriana, Oedaleus infernalis, Epacromius coerulipes, Chorthippus dubius, and Bryodema gebleri (Ma 1991; Zheng 1992). They occur mainly in the Inner Mongolia-Xinjiang faunal division, affecting mostly the steppe, desert, and meadow grasslands. Grassland caterpillars (more specifically tussock moths) are the second most widely occurring pest group, of which the species of the family Lymantridae are most representative, including Gynaephora alpherakii, G. qinghaiensis, G. aureata, G. ruoergensis, and G. minora. These mainly infest alpine grasslands in the Qinghai-Tibet faunal division. Less noticeable pest species include Loxostege sticticalis in the family Pyralidae and Geina invenusta in the family Chrysomelidae (Li and Li 1996). From 2006 to 2013, roughly 5% of the total grassland area nationwide had been subject to insect damages (Table 2.14).

Table 2.15 Soil faunal composition in some pilot terrestrial ecosystems of Chinaa Phyla Protozoa Turbellaria Rotatoria Nemata Annelida Mollusca Tardigrada Arthropodac Soil fauna

No. family 77 1 6 51 10 8 4 351 508

No. genus 137 1 10 111 29 10 12 727 1037

No. Spp.b 290 1 10 194 244 154 45 2276 3214

Note: aAdapted from Yin (2000); bincluding the unidentified; cincluding at least 19 orders of 9 classes

2.9

Poorly Documented Soil fauna

Soil fauna involves nearly all the major groups of terrestrial invertebrates in China. Hwever, no nationwide comprehensive surveys on soil fauna have ever been organized to date, except for that conducted by Yin and her colleagues (2000) which only dealt with a few pilot ecosystems characteristic of different climatic zones and focused primarily on the forest ecosystems. Nevertheless, a total of 3214 species (including those unidentified) belonging to 1037 genera and 508 families were recognized and recorded in these limited ecosystems, reflecting the high diversity and abundance of soil-dwelling invertebrates in Chinese ecosystems (Table 2.15). In a typical steppe of the Xilin Gol grassland, 15 soil animal orders affiliated to 8 classes and 6 phyla were classified in soils sampled at six stands (He et al. 1988). Due to difficulties in identification, only 23 families in three phyla (Annelida, Tardigrada, and Arthropoda) were figured out, while those in the phyla Platyhelminthes, Nemathelminthes, and Mollusca could only be distinguished into classes. In terms of individual abundance, nematodes (Nematoda) were the most dominant taxon in the area, while arthropods (mainly Hymenoptera, Coleoptera, Acarina, and Araneida) ranked second. Ants (Formicidae in the order Hymenoptera)

2.10

Little Known Soil Microorganisms

were the most prominent group and two families (Carabidae and Scarabaeoidae) in the order Coleoptera formed an important associate group. In addition, annelids (earthworms of the family Enchytraeidae) and rotifers were commonly found in various habitats, although their abundances were generally low (He et al. 1988; Chen et al. 1990). By contrast, the soil fauna in the alpine meadow grassland has been more intensively investigated. Some 204 soil faunal species have been identified, with Protozoa (73 species), Nematoda (58 species, 47 genera, 27 families and 6 orders), Lepidoptera (34 species of 7 families), Arachnida, Protura, and Diplura accounting for 36%, 29%, 17%, 12%, 3%, and 3% of the total species number, respectively. Macrofauna (>2 mm) is dominated by Coleopteran species, accounting for 64% of the total abundance in the macro soil animal category, including such arthropods as beetles, centipedes, grubs, maggots, millipedes, spiders, termites, and woodlice, while the rest are mainly annelids (earthworms) and mollusks (snails and slugs). Mesofauna (0.1-2 mm) consists mainly of Acarina (mites, 72.6%) and Collembola (springtails, 17.1%). Microfauna consists mainly of Protozoa, in which Flagellata, Sarcodina, and Ciliata account for 89.9%, 9.4%, and 0.4% of the total individual number, and nematodes, in which Acrobeloides spp. and Aporcelaimus spp. are most predominant. In addition, 14 Proturan species in 7 genera are recognized in this ecosystem. Soil fauna in the montane meadow and steppe ecosystems was investigated only at a few locations on the vertical belt of the Changbai Mountains. Limited literature shows that in terms of abundance, Collembola and Enchytraeidae are the most dominant, while Acarina and Nematoda are important common groups, whereas Coleoptera and Diptera are only associate groups. However, this sequence of dominance appears to vary by year. Tardigrada had been traditionally regarded as a typical group in the montane grassland, while this has not been attested to by ensuing investigations. A total of 105 mite species in Acarina were identified, with a density of 15,287 individuals /m2 measured, whereas Protozoa (108 species), Nematoda (54 spp., 44 gen., 28 fam., 8 ord., and 2 classes), and Coleoptera (43 species) were revealed to be the common groups (Yin et al. 1984). Soil fauna in the hot shrubby tussock rangeland likely can be estimated by referring to that of the forest ecosystem of the same area. In two areas of the subtropical broadleaved evergreen forest region where various shrubby tussock stands are abundantly interspersed within the forests, some 606 soil animal species have been recorded, with 431 accurately identified. Taxonomically, Arthropoda is the largest group, which consists of 244 species, 201 genera, and 132 families. Protozoa is the second largest, which comprises 116 species, 68 genera, and 46 families. Nematoda consists of 32 species belonging to 29 genera and 11 families. The rest of the species belong to Oligochaeta (18 spp., 17 gen. and 5 fam.), Gastropoda (15 spp., 10 gen. and 8 fam.), and a few other classes.

41

Earthworms may be among the functionally most important soil faunal groups in grassland ecosystems (Brady and Weil 2002). As of the year 2000, some 232 earthworm species had been identified in China, assigned to 25 genera and 8 families. However, the number of species occurring in the temperate grassland region is extremely poor, with only 8 earthworm species found in the Inner Mongolia-Xinjiang division and 2 species in the Qinghai-Tibet division. In addition, 4 Isopoda species are recorded in Inner Mongolia, while 115 mite species are identified in northeast China. Approximately 103 spider species in 22 families are found in the two major grassland regions, of which 79 species in 13 families are found in the temperate zone, while the remaining 24 species of 9 families are found in the alpine grassland region. For the Proturan group, 7 species in 6 families are found in the Inner Mongolia-Xinjiang division, while 14 species of 7 families are found in the Qinghai-Tibet division, most of which are endemic to these regions. Yin (2000) showed that the species richness as well as the individual abundance of soil fauna decreased considerably with decreasing temperature in China. For example, the total species number decreased from 603 species in the Xishuang Banna region (tropical) to 431 species in the suburban Beijing (temperate), and further down to 204 species in the alpine region of Qinghai Province. Other environmental factors such as precipitation, soil properties, and vegetation type are also important in determining the species richness, individual abundance, and spatiotemporal patterns of soil fauna.

2.10

Little Known Soil Microorganisms

As we know, organisms are usually divided into two fundamentally different types, namely the prokaryotic organisms and the eukaryotic organisms. All bacteria are prokaryotic, while algae, fungi, Protozoans, higher plants, and animals are eukaryotic. For many years, organisms on Earth had been categorized into five kingdoms: Monera, Protista, Fungi, Animalia, and Plantae. However, it is now clear that there exist two quite distinct groups of prokaryotes: the Bacteria and the Archaea. Moreover, strong evidence suggests that the kingdom of Protista should be further divided into at least three kingdoms. Therefore, the three-domain system appears increasingly prevalent at present, including the Bacteria (the true bacteria or eubacteria), Archaea, and Eucarya (all eukaryotic organisms) domains (Prescott et al. 2002). Studies on the classification of species and functional groups as well as on the functions of soil microbes in Chinese terrestrial ecosystems are relatively inadequate, particularly for grassland ecosystems. As of 1998, some 266 bacterial species of 60 genera had been identified in China, of which only one-third were found in the soil. By contrast, while more than 2000 species in 60 genera of Actinomycetes had been

42

2 Overview of Chinese Grassland Ecosystems

identified and described internationally, only 450 species of 40 genera had been identified and preserved in China, with 8 genera established by Chinese microbiologists (NBEP 1998). Some 44 species and 6 genera of the Frankia-Symbiotic Nitrogen Fixation Actinomycetes were identified in China, with 19 species being recorded for the first time anywhere in the world, some of which infect the desert and meadow shrubs such as Elaeagnus oxycarpa and Hippophae rhamnoides. In addition, several species or genera of the legume-associated bacteria have been identified, including two species of Sinorhizobium, Rhizobium huakuii, Rhizobium tianshanellse, Bradyrhizobium liaoningense, and Mesorhizobium, which are relevant to the grassland ecosystems. It is estimated that there could be as many as 180,000 species of fungi awaiting identification in China, while virtually only 7500 species have been recorded. Soil fungi are generally poorly documented, with only a few genera studied in detail. Examples of these well-studied Chinese genera include 89 species in the genus Aspergillus, 70 species in the genus Penicillium, 642 species, 68 genera, and 29 families of ectomycorrhial fungi, and 40 or so species of endomycorrhizal Fungi (VAMF). Studies on soil microorganisms in Chinese grassland ecosystems are mostly conducted at the local scale and are concentrated more on the composition and seasonal variations in biomass of the major soil microbial groups of higher taxonomical taxa or functional groups, while very few have dealt with classification and composition characteristics at species or genus levels. Prior to the year 2000, the alpine meadow grassland ecosystem and the typical steppe ecosystem were the most intensively studied cases in this regard. For example, seasonal changes and distribution patterns in the soil of the biomass of bacteria, actinomycetes, fungi (filamentous), yeast, oligonitrophiles, and cellulosedecomposing microorganisms were systematically measured at 10 meadow communities in the alpine meadow of Qinghai (Zhu et al. 1982). By contrast, the three major microbial types including aerobic, anaerobic, and bacillus functional groups were measured at two steppe communities in the Xilin Gol grassland of Inner Mongolia (Liao et al. 1985). Liu and Liao (1997) identified 9 bacillus species and 17 species of filamentous fungi in the same area. In addition, Liao and Zhao (1997) also conducted a contrasting study on the biomass and composition of the major microbial groups in the meadow, typical, and desert steppes as well as the steppic desert.

2.11

Reduced Degradation and Compromising Conservation

As discussed previously, grassland degradation has been and is currently a serious environmental issue challenging governments at grassroot, regional, and provincial levels

(Liu and Diamond 2005). However, just how seriously Chinese grasslands were and are degraded has been a controversial issue perplexing Chinese grassland ecologists for several decades. The proportion of degraded grassland in relation to the nation’s total grassland area has been variably estimated to range from 50.24% (Li 1997) to 90% (Liu and Diamond 2005). Based on the data for the major grassland-owning provinces collected during the first national rangeland baseline survey in the 1990s, it appears that Li B’s estimate (1997) was much closer to the truth at that time. Note that Li’s calculation was conducted using a book-keeping approach based on vast amounts of field data, and referred to a number of yearbooks, monographs, and professional literature concerning vegetation, livestock, soil, geography, and land use at local, provincial, and national scales, supplemented with remote-sensing images. More importantly, he calculated that the amount of newly degraded grassland had increased annually by 1.9% nationwide during the 15 years before 1997. We infer that the estimate provided by Liu and Diamond (2005) in all probability had been calculated in light of this increasing rate. However, a very critical fact might have been neglected by Liu and Diamond; i.e., that China initiated its nationwide grazing-prohibition program in the year 2000. This program, which is still in operation, has made it so that two-thirds of China’s rangelands have been under year-round or seasonal exclusions of livestock grazing (CMA 2013). Therefore, we contend that the maximum proportion of degraded rangelands in China has been no more than 60% that occurred during the 1980s and the 1990s, the period of the most prevalent overgrazing in the country. What matters most is that the definition, standard, and approach for assessing the degradation regimes are still not available up to present in China. Grazing exclusion has been considered one of the most effective and feasible approaches to restoring degraded grasslands and promoting their carbon sequestration capacity. The “subsidized livestock exclusion for grassland recovery” campaign, one of the largest ecological restoration actions ever adopted in the world, aimed principally at curbing further degradation and restoring degraded grassland ecosystems in China. Since its implementation, about 258 million hectares of grasslands have been subjected to treatments of complete no-grazing, summer-only grazing, or rotational (shifting) grazing. The effects of two-decades’ worth of livestock exclusion on the grassland structure and function have been evaluated by several authors, that of which Hu et al. (2016) takes the lead. Their synthesis shows that the soil carbon contents in 299 out of the total 326 measurements (i.e., 92%) at 51 sites in the various grassland types nationwide increased with grazing exclusion during this period, with the increased rate of soil carbon averaging to about 0.37 Kg m2 yr.1. Grazing exclusion

2.11

Reduced Degradation and Compromising Conservation

also promoted both the above- and belowground plant biomass of standing crops at a rate of 21.1 g m2 yr.1 (Hu et al. 2016). Although the pest insect- and rodent-stricken areas remained constant, the number of outbreaks dropped substantially during the period, largely due to increases in vegetation coverage and improvements in grass quality. A recent study shows that N enrichment in the host plants decreased the size and viability of some dominant locust species in Inner Mongolian grasslands (Cease et al. 2012). Because many insects have specific dietary plant species-foraging targets for protein, carbohydrates, and other nutrients, shifts in species composition may become a major factor determining pest outbreaks caused by changes in community succession in association with livestock grazing regimes in the future. Given that humans have substantially altered ecosystem N cycling through fossil fuel combustion, agricultural fertilizer application (Herrero et al. 2013), and domesticated animal production (Matson et al. 1997), insect dynamics may be affected in unanticipated ways. Therefore, better understanding the impacts of these anthropogenic activities is crucial to developing sustainable land management practices that minimize economically damaging insect outbreaks in the vast regions of Chinese grasslands. However, the benefits, constraints, and global implications of the “livestock exclusion for grasslands” program need to be analyzed on a more sound and scientific basis in terms of the following aspects: 1) changes in standing crop biomass and species diversity and richness of various major biotic types and groups in addition to plants, along with their functions within the ecosystems in question; 2) improvements in the physical, chemical, and biological traits of soil; 3) regional changes in the biogeochemical cycling of water and nutrients; and 4) occurrences of pest outbreaks, sandstorms, and soil erosion. These analyses are necessary due to the fact that, while grasslands might have become improved in some aspects, the long-term indiscriminate removal of livestock grazing also could engender some unexpected ecological or economic outcomes, such as the considerable waste of plant forage biomass, lowered primary production, detritus accumulation that is prone to catching fire, and arrested vegetation regeneration (Godfray et al. 2010). In addition to livestock exclusion, the Chinese government has also made great efforts on many other aspects to improve and protect China’s grassland resources, the achievements of which are rather remarkable. Since 1985 when the first national grassland laws were issued, a series of subject regulations at the provincial level have been formulated accordingly, concerning the prohibition of grassland cultivation, restriction of overgrazing, prevention of medicinal herb-digging, mining and off-road driving, control of wild fires, elimination of pest insects and rodents, and many others (CMA 2013). Since 2000, several large-scale

43

grassland improving- and environment-harnessing projects have been initiated successfully, such as the Beijing-Tianjin affecting sandstorm source control project, the southwestern lava regions’ grassland improvement project, and the grassland control project in the upper reaches of the “Three Rivers,” i.e., the Yangtze, Yellow, and Lancang rivers. Protection of wildlife and grassland plants has been particularly stressed in China, with strict punishments for the unlawful picking and digging of medicinal plants and poaching of wild animals. China probably possesses one of the most all-encompassing grassland monitoring and early disaster warning systems at the grassroots, regional, and provincial levels. As of 2011, some 997 county-level grassland monitoring stations had been set up in 23 provinces, with some 4000 technical personnel undertaking various relevant tasks such as in situ measurements, data-collection, and household interviews. The “three S” techniques along with database building and internet transmission are routinely applied, with two official professional networks (www.grassland. gov.cn and www.caaa.cn/association/grass) available that provide past and current data regarding the forage yield, utilization and management status, pest conditions, climate and weather forecasts, recommendations for materials, techniques, forage varieties, breeds and strains for local, regional or provincial grassland purposes all across the country. During the twelfth “five-year period” (from 2011 to 2015), the “Grassland Protection and Construction Outline” stipulated that seven projects involving grazing exclusion, forage variety breeding, prevention and elimination of grassland hazards, construction of nature reserves, building up of the technical system for monitoring and inspecting grasslands, construction of artificial pasture bases in the cow-raising belt, and the demonstrative transformation and innovation of traditional animal husbandry would be implemented in 13 regional grasslands (CMA 2013). As of 2011, about 0.4 million km2 of pastures had been fenced, including 168,000 km2 of year-round grazing-free enclosures, 190,000 km2 of seasonally delayed grazing enclosures, and 8100 km2 of rotational grazing enclosures. In addition, the frequency and intensity of such disastrous events as fires, snowstorms, pest insect and rodent outbreaks, soil erosion, and plant disease occurrences all showed a decreasing trend. During the same period, permanent artificial pastures amounted to 195,110 km2, with Inner Mongolia, Gansu, Sichuan, Xinjiang, and Heilongiang as the major growing provinces. Ecologically and environmentally, the degrading momentum of Chinese grasslands has been effectively suppressed. The overall grass coverage and total forage yield have increased by 4% and 10.6% at the national scale, respectively, in comparison with those before the implementation of the “subsidized livestock exclusion for grasslands” project

44

2 Overview of Chinese Grassland Ecosystems

Table 2.16 Dry forage yields of the major grassland regions and in the country as a whole between 2006 and 2011 (million tons)a Province Inner Mongolia Xinjiang Gansu Sichuan Tibet Qinghai Yunnan Nationwideb

2006 53.053 30.250 10.599 24.499 23.383 25.012 13.673 265.232

2007 47.379 30.561 11.735 26.388 23.741 22.877 16.422 261.825

2008 56.240 23.619 11.212 25.671 25.760 21.882 14.595 259.513

2009 46.052 27.304 11.711 26.706 25.502 25.702 13.795 257.462

2010 50.137 31.427 12.138 27.681 25.145 27.244 13.340 284.340

2011 55.594 29.472 12.075 27.570 28.121 24.507 14.692 291.052

Aver. 51.409 28.772 11.578 26.419 25.275 24.537 14.420 269.904

Note: aAdapted from CMA (2013); balso including those in the remaining 16 provinces

(CMA 2013). Locally during the decadal grazing exclusion period between 2000 and 2010, the total area of degraded pastures in Xijiang was reduced by 2.4%, the average forage yield increased by 48.8% in the enclosed or seasonally grazed pastures in Qinghai, the coverage and forage yield increased by 25–50% and 30% in Ningxia, and the grass canopy coverage increased by at least 20% in different regions of Inner Mongolia. Since 2006, the annual total forage yield in the nation exceeded one billion tons (fresh weight) for the first time (Table 2.16). Mounting evidence proves that livestock removal is an ideal means of restoring degraded grassland ecosystems. However, when practiced alone, it is not sufficient enough to substantially promote plant biomass production and enhance ecological services given the time needed. In this respect, designed management measures would yield twice the result with half the effort (Matson et al. 1997). In China, various measures have been designed and implemented. For example, the straw hedgerow gird method can accelerate vegetation reconstruction of seriously desertified grasslands and on shifting sand dunes by preparing the buffer seed bed for pioneering plant establishment, which shortens the time that would otherwise be needed by two-thirds. Reseeding native leguminous species into natural pastures may substantially promote NPP and improve forage quality at the same time. Shallow cutting of the sod has been shown to significantly stimulate the growth of rhizomatous grasses in the northeast meadow steppe. Seedling-inserting technology has been very effective in repairing exposed patches and eroded pits, revegetating heavy soda resultant saline-alkaline soil, conserving endangered species, and introducing medicinal herbs into the semi-humid grasslands (Li et al. 2012). The three-ring paradigm for sandy grassland rehabilitation has proved to be very successful in restoring the sandy vegetation at the landscape scale in north China (Zhang et al. 1998a, b). Based on these sorts of innovative technologies, the accurate farming of grasslands (AFG), a highly designed, targetoriented, and artificially manipulated synthetic approach for reconstructing, rehabilitating, as well as improving all-case grasslands, has been established and put into experimental

practice in China (Li et al. 2012). In contrast to precision agriculture, this paradigm emphasizes the precise and sitespecific manipulation of the grass-soil system by matching resource availabilities with demands in terms of the time, site, and amount. AFG is characterized by the intensive management of the grassland ecosystem by means of increased material and manpower inputs, advanced agro-ecological practices, and particularly by favorable livestock-grassland interactions. It aims at promoting vegetation coverage and forage production and enhancing the functions of ecosystem services such as carbon sequestration, soil and water conservation, and biodiversity preservation. However, it should be kept in mind that the impacts of these intensive measures, such as the effects of reseeding leguminous species in natural grasslands on the reactive nitrogen enrichment, artificial pasture establishment on the groundwater systems, introduction of alien cultivated forage species on the biodiversity, largescale pesticide and herbicide application for grasshopper and pest rodent control on human health, and aerial fertilization on the soil quality, should be strictly evaluated before being put into practice. Species invasion is also a critical element restricting the success of the various ecological restoration projects in China, because it can impose considerable pressures on the native species and has substantial long-term effects on ecosystem services (Foley et al. 2005; Norton 2009). Effective control measures to cope with the threats posed by invasive species are still lacking in China.

2.12

Delinking of Livestock With Grasslands

Currently about one-third of the global land area is being used for grazing livestock (Steinfeld et al. 2006). Except in barren areas (dry or cold deserts) and dense forests, pastures are present in nearly all regions (Steinfeld et al. 2006). Pasture plays a critical role in the net primary production, creating or regenerating soils, and adjusting the atmospheric composition. It also provides many other ecological services such as soil and water conservation and biodiversity

References

maintenance. Most importantly, it supports animal husbandry to produce animal products of all kinds, contributing substantially to the food security of the ever-growing world population. However, given the rapid development of the industrial livestock sector, livestock at present is no longer tied to local pastures for feeding purposes or used to supply animal power or manure for crop production, engendering the delinking of livestock from the grasslands worldwide (Naylor et al. 2005). With the world’s continuously growing population, rapid urbanization, and the forceful momentum of economic growth in developing countries, global meat consumption will increase even more rapidly, leading to intensified dependence on meat supplied from large-scale hog and chicken raising operations (Tilman et al. 2002). Livestock production has become a highly industrialized process wherein several thousand heads of cattle and pigs or 100,000+ chickens are fed grains and kept in a single facility. When industrial operations in which domestic animals are raised in confinement arrests the return of manure to fields where feed is produced, it leads to the decoupling of livestock and land. Industrial livestock operations also cause serious on-site and off-site environmental issues via the discharge of liquid waste, which contaminates rivers and groundwater (Jackson 2002; Steinfeld et al. 2006). Moreover, the trend is shifting via international trade in meat and feed between supplying and consuming countries, leading to coupled environmental and resource consequences locally, regionally, and even trans-nationally (Liu and Diamond 2005). Some research workers pointed out that prohibition of livestock grazing in the long run will unavoidably lead to a shift in China’s meat dependence from beef and mutton to pork and chicken, with an estimated 30% increase in the production of pork and chicken by 2020. This alone would require an additional 20.3 million hm2 of croplands for feed production. China’s ambitious blueprint for nationwide urbanization as well as the loosening of the one-child only policy would further compound the nation’s already inadequate availability of croplands. Ecologically, livestock production is a key driver for the major biogeochemical processes and ecological functions in the grassland ecosystems and thus also has a substantial influence at the global scale. Livestock grazing exclusion at the country scale in China would potentially lead to mutual conversions between croplands and pastures, give rise to a shift away from the extensive grassland-based livestock production system towards an intensive grain-based one, and result in changes in land-use patterns (grazing vs. mowing) and intensities at various temporal and spatial scales, which together may impose a chain of ecological consequences. In addition, ecological migration and the resultant population redistribution would engender unexpected social and economic outcomes.

45

Breaking the delinking trend between livestock and land is an ever-increasing challenge facing decision-makers, scientists, and the public as a whole, wherein incentiveoriented policies for pasture-raised livestock production will play an important role. Traditionally, livestock production had been based on locally available feed resources, and animal manure was often essential in maintaining soil fertility. Mobile forms of livestock production or transhumance had been created to utilize grassland resources, which proved to be sound and sustainable means of production both ecologically and in terms of the ecosystem services garnered from the broad semiarid and mountainous regions of north China. These experiences deserve to be used as reference when seeking the solution of the challenge.

References Bai YF, Wu JG, Clark CM, Pan QM (2012) Grazing alters ecosystem functioning and C:N:P stoichiometry of grasslands along a regional precipitation gradient. J Appl Ecol 49:1204–1215 Brady NC, Weil RR (2002) The nature and properties of soils. Kluwer Academic Publishers, Prentice Hall, NJ Cease AJ, Elser JJ, Ford CF, Hao S et al (2012) Heavy livestock grazing promotes locust outbreaks by lowering plant nitrogen content. Science 335:467–469 Chen ZZ, Huang DH, Cai WQ, Wang JW, Kang SA et al (1990) Research on chestnut soil at the Xilin River Basin of Inner Mongolia. J Arid Land Resour Environ 4(3):18–24 Chen S (1994) Forage plant resources of Chinese Grasslands. National Publishing House of Liaoning, Shenyang CMA (Chinese Ministry of Agriculture) (2013) Report on Grassland Development in China. Agriculture Press of China, Beijing Coupland RT (1993) Overview of the grasslands of Europe and Asia. In: Coupland. In: Ecosystems of the World 8B-Natural grasslands (Eastern Hemisphere and Résumé). Elsevier, New York, pp 1–2 CPGCAS (Committee of Physical Geography of Chinese Academy of Sciences) (1985) Physical geography of China. Science Press, Beijing Foley J et al (2005) Global consequences of land use. Science 309:570–574 Godfray HC et al (2010) Food security: the challenge of feeding 9 billion people. Science 327:812–818 Guo SJ, Cui HX (1996) Temperate and warm-temperate desert and montane steppes of northwest China. In: Liao GF, Jia YL (eds) Rangeland resources of China. China Science & Technology Press, Beijing, pp 435–453 He DM, Liu YJ, You WH, Chen ZY (1988) Ecological study on soil animals in Inner Mongolia steppe. Res Grassland Ecosyst 1:139–149 Herrero M, Havlík P, Valin H, Notenbaert A, Rufifino MC et al (2013) Biomass use, production, feed efficiencies, and greenhouse gas emissions from global livestock systems. PNAS 110(52):20888– 20893. www.pnas.org/cgi/doi/10.1073/pnas.1308149110 Hong J, Mo XJ, Lin J, Zhang HQ (2014) Analysis of damages and controls of pest rodents in China’s natural grasslands. Chin J Grassl 36(3):1–4 Hu ZM, Li SG, Guo Q, Niu SL et al. (2016) A synthesis of the effect of grazing exclusion on carbon dynamics in grasslands of China. Global Change Biology. https://doi.org/10.1111/gcb.13133 Jackson D (2002) The farm as natural habitat. Island Press, Washington, DC, pp 13–26

46 Jia SX (ed) (1995) Forage plants in China, vol 5. Chinese Agriculture Press, Beijing Lavrenko EM, Karamysheva ZV (1993) Steppes of the former Soviet Union and Mongolia. In: Coupland RT (ed) Ecosystems of the World 8B-Natural grasslands (Eastern Hemisphere and Résumé). Elsevier, New York, pp 3–59 Li LH (2017) An estimate of the sporadic land in the grassland regions of China. Unpublished Li B, Wang JT, Lei MD, Liu ZL et al (1980a) Steppe and Savanna. In: Wu et al (eds) Vegetation of China. Science Press, Beijing, pp 505–582 Li B, Liu ZL, Lei MD (1980b) The temperate steppe zone. In: Wu et al (eds) Vegetation of China. Science Press, Beijing, pp 917–955 Li B (1997) Rangeland degradation in north China and its preventive strategy. Sci Agric Sin 30(6):2–9 Li HC, Chen YL (1988) Study on the fauna of Acridoids in the typical steppe subzone of Xilin River Basin, Inner Mongolia. Res Grassl Ecosyst 2:26–44 Li WW, Li SD (1996) Control of insect pests. In: Liao GF, Jia YL (eds) Rangeland resources of China. Science and Technology Press, Beijing, pp 532–536 Li M, Chen WJ, Wei W, Wang C et al (2012) Diversity of breeding birds in middle Inner Mongolia. Chin J Zool 47(3):102–108 Liang Y, Zhou GS, Zhang F (2013) Effects of different grazing intensities on grassland production in China: a meta-analysis. PLoS One 8(12):e81466 Liao YN, Zhang GZ, Wang FJ (1985) Seasonal changes and soil depth vertical distribution of soil micro-organisms in the Xilin River Basin of Inner Mongolia. Res Grassl Ecosyst 1:180–192 Liao GF, Jia SX (eds) (1996) Rangeland resources of China. Chinese Science and Technology Press, Beijing Liao YN, Zhao J (1997) Studies on soil microorganisms and their activities in the steppe and desert zones of Inner Mongolia. Res Grassl Ecosyst 5:227–239 Liu Q, Wu XH (1996) Warm tussocks. In: Liao GF, Jia YL (eds) Rangeland resources of China. China Science & Technology Press, Beijing, pp 250–256 Liu DF, Chen SH, Wu LJ (1996) Overview of rangeland resources in China. In: Liao GF, Jia YL (eds) Rangeland resources of China. China Science & Technology Press, Beijing, pp 343–352 Liu LP, Liao YN (1997) Biological characteristics and biodiversity of soil microorganisms in Leymus chinensis steppe and Stipa grandis steppe under different grazing intensities. Res Grassl Ecosyst 5:78–86 Liu JG, Diamond J (2005) China’s environment in a globalizing world. Nature 435(30):1179–1186 Ma Y (1991) Grassland insects in Inner Mongolia. Tianze Press, Yangling, Shaanxi Ma F, Zhang JL (eds) (2009) Investigation of important terrestrial wildlife resources in China. Forestry Publishing House of China, Beijing Matson PA, Parton WJ, Power AG, Swift MJ (1997) Agricultural intensification and ecosystem properties. Science:277, 504–509 Miao Z (1996a) Temperate steppe desert type. In: Liao GF, Jia YL (eds) Rangeland resources of China. Chinese Science and Technology Press, Beijing, pp 227–233 Miao Z (1996b) Temperate steppe type. In: Liao GP, Jia SX (eds) Rangeland resources of China. Science and Technology Press of China, Beijing, pp 188–204 Naylor R, Steinfeld H, Falcon W, Galloway J, Smil V et al (2005) Losing the links between livestock and land. Science 310 (5754):1621–1622 NBEP (National Bureau of Environment Protection) (1998) Report on the National Conditions of Biodiversity in China. China Environmental Science Press, Beijing

2 Overview of Chinese Grassland Ecosystems Norton DA (2009) Species invasions and the limits to restoration: Learning from the New Zealand experience. Science 325:569–571 Pan YQ, Xing LL, Yang GS (2006) A preliminary study on avifauna revolution in Wuliangsu wetland during the last 10 years. Acta Sci Nat UnivNei Mongol 37(2):170–174 Prescott LM, Harley JP, Klein DA (2002) Microbiology. Higher Education Press, Beijing Qin YL (1983) Faunal composition and distribution of rodents in regions to the south of the Yangtze River. Chin J Zool 6:14–17 Shen HH, Zhu YK, Zhao X, Geng XP et al (2016) Analysis of current grassland resources in China. Chin Sci Bull 61(2):139–154 Song ZR (1996) Temperate deserts. In: Liao GF, Jia YL (eds) Rangeland resources of China. China Science & Technology Press, Beijing, pp 2233–2247 Steinfeld H, Gerber P, Wassenaar T et al (2006) Livestock’s long shadow: environmental issues and options. Food and Agriculture Organization of the United Nations, Rome, Italy Su DX (1996) Utilization of Chinese grasslands. In: Liao GF, Jia YL (eds) Rangeland Resources of China. China Science & Technology Press, Beijing, pp 503–518 Sun ZY, Liu Q, Liu XH (1996) Swamps. In: Liao GF, Jia YL (eds) Rangeland resources of China. China Science & Technology Press, Beijing, pp 325–328 Sun QH, Zhang ZW (2000) The impact of climate warming on the distribution of Chinese birds. Chin J Zool 35(6):45–48 Sun XL, Ren BZ, Zhao Z, Gao CQ, Zhou GP (2006) Faunal composition of grasshoppers in different habitats of northeast China. Chin J Ecol 25(3):286–289 Sun XJ (2016) Species diversity and geographic distribution of Tenebrionid beetles in the Mongolian Plateau. Master’s thesis, Hebei University, Baoding Suttie JM, Reynolds SG, Batello C (eds) (2005) Grasslands of the world. FAO, Rome Tang HP, Liu SR (2001) The list of C4 plants in Inner Mongolia. Acta Sci Nat Univ Nei Mongol 32(4):431–438 Tao SL, Fang JY, Zhao X, Zhao SQ et al (2015) Rapid loss of lakes on the Mongolian Plateau. PNAS 112(7):2281–2286 Tilman D, Cassman KG, Matson PA, Naylor R, Polasky S (2002) Agricultural sustainability and intensive production practices. Nature 418:671–677 Wang YX, Zhang SY (1993a) The list of mammalian species in China (1). Wildl China 2:12–17 Wang YX, Zhang SY (1993b) The list of mammalian species in China (2). Wildl China 3:6–11 Wang YX, Zhang SY (1993c) The list of mammalian species in China (3). Wildl China 4:11–16 Wang YX, Zhang SY (1993d) The list of mammalian species in China (4). Wildl China 5:10–11 Wang K, Sun ZY, Liu Q, Zhu JZ (1996) Lowland meadows. In: Liao, Jia (eds) Rangeland resources of China. China Science & Technology Press, Beijing, pp 279–296 Wang P, Yin LJ, Li JD (1997) Ecological distribution and physiological adaptation to saline-alkaline environment of C3 and C4 plants in the northeast China grassland region. Chin J Appl Ecol 8(4):407–411 Wang KF, Zhang JR, Lei FM (2010) Geographical distribution pattern and the tempo-spatial variations of China’s avifauna. Acta Zootaxon Sin 35(1):145–157 Wu HP (1996) Survey on snake species in the Hengshan Mountains of south Hunan. Chin J Zool 31(1):16–18 Wu Y, Jin CX (1982) The meadow vegetation and insects. Alpine Meadow Ecosyst 1:110–116 Wu PQ, Liu Q (1996) Dry-hot savannas. In: Liao GF, Jia YL (eds) Rangeland resources of China. China Science & Technology Press, Beijing, pp 277–279

References Xing F, Gao WC, Yu YP, Ren BZ (2005) Survey on the species diversity of grasshoppers in different habitats of northeast China. J Jilin Norm Univ 1:20–22 Xue SM (1996) Alpine desert steppes. In: Liao GF, Jia YL (eds) Rangeland resources of China. China Science & Technology Press, Beijing, pp 225–227 Yao JC (1991) Thirty year investigation on the changes in avifauna on the Taibai Mountains of Shaanxi Province. Chin J Zool 26 (5):19–29 Yin SG, Yang MX, Zhang TW (1984) Investigation on soil mites at the spruce-fir forest belt and the Korean pine mixed forest belt on the north slope of the Changbai Mountains. Res Forest Ecosyst 4:175–179 Yin LJ, Li MR (1997) A study on the geographic distribution and ecology of C4 plants in China. Acta Ecol Sin 17(4):350–363 Yin WY (2000) Soil animals of China. Science Press, Beijing Zhang Q, Zhao X, Zhao HL (1998a) Desert Rangelands in China. Chinese Meteorological Press, Beijing Zhang YM, Fan NC, Wang QY, Jing ZC (1998b) The changing ecological process of rodent communities during rodent pest management on alpine meadow. Acta Theriol Sin 18(2):137–143

47 Zhang ZT, Liu Q (1992) Rangeland Resources and Utilization in the Main Pastoral Regions of China. China Science and Technology Press, Beijing Zhang ZT (1996) Grassland soils of China. In: Liao GF, Jia YL (eds) Rangeland resources of China. Science and Technology Press of China, Beijing, pp 38–57 Zheng ZM (1992) Acridoids in Ningxia. Shaanxi Normal University Press, Xian Zheng GM (2011) Avifauna and Species Distribution List in China. Science Press, Beijing Zhou SR, Zhang JS (1996) Hot shrubby tussocks. In: Liao GF, Jia YL (eds) Rangeland resources of China. China Science & Technology Press, Beijing, pp 272–277 Zhou LZ, Ma Y, Ye XD (2002) Distribution of glires in arid regions of China. Chin J Zool 48(2):183–194 Zhu GR, Li JZ, Tang SH, Yang T (1982) Microbiological studies on soils of the alpine meadow ecosystem at the Haibei Research Station. Alpine Meadow Ecosyst 1:144–161 Zhu TC, Guo SX, Li XL, Liu Q, Wu XH (1996) Temperate meadow steppe. In: Liao GF, Jia YL (eds) Rangeland resources of China. China Science & Technology Press, Beijing, pp 175–187

3

Natural Conditions Influencing Chinese Grassland Ecosystems

Abstract

This chapter elaborates upon the geographic, geomorphic, edaphic, and climatic factors that influence the genesis, distribution, and development of Chinese grassland ecosystems. Its first section mainly deals with the major land forms that are most commonly associated with Chinese grasslands, especially the major plateaus, plains, mountains, and river valleys. Its second section focuses on the climatic aspects and introduces the major climate zones along with the overall patterns of temperature and precipitation of the country as a whole. Its third section discusses at length all the soil types supporting Chinese grassland ecosystems, with emphasis on the genesis, soilforming processes, physical properties, and chemical reaction types of the major soil types. Keywords

Geography · Land form · Soil type · Soil property · Soilforming process

The current pattern and status of Chinese grassland ecosystems is generally determined and controlled by climate, geographic and geomorphic elements, soils, and human disturbances. However, within each of the three sub-zonobiomes, i.e., the temperate grassland, the QinghaiTibet alpine grassland, and the warm-hot shrubby tussock rangeland, dominant environmental factors differ substantially. Climate, through the agencies of sun, wind, and rain, acts on the parent materials to form various biotopes for the grassland biota to colonize and evolve in. Soils and plants influence the climate through reflection and emission of the sun’s radiance and exchanges of matter and energy. Therefore, the grassland ecosystem of a given area or region is usually under the influence of a combination of interacting atmospheric, edaphic, and biotic processes to maintain its highly dynamic trajectory of existence and succession. # Springer Nature Singapore Pte Ltd. 2020 L. Li et al., Grassland Ecosystems of China, Ecosystems of China 2, https://doi.org/10.1007/978-981-15-3421-8_3

3.1

Physical Features

China is situated in the southeastern part of the Eurasian Continent and occupies a total land area of 9.6 million km2 (Zuo and Xing 1992). The general land contour is characterized by the fact that the western part is higher than the eastern, with a roughly 0.8 m decrease in elevation per kilometer of horizontal displacement from west to east. The relief is most often described as “staircase-like” and geographically divided into three levels (steps) according to elevation. The first level is composed of the entire QinghaiTibet Plateau, which is about 2.3 million km2 in area with 4000 m mean elevation. The second level comprises Xinjiang in the northwest, pan-Inner Mongolia in the north, and the subtropical region of southwest China, with a total area of some 4 million km2 and elevations ranging from 1000 to 2000 m. The third level includes the entire northeast China, the North China plains, and southeast China, which extends over a total area of 3.3 million km2 with elevation less than 500 m on average (Ying and Yang 1992). The division line between the first and the second levels runs along the Kunlun, Altun, and Qilian Mountains in the west-east direction and then turns southwards through to the Hengduan Mts., whereas the division line between the second and the third levels follows a northeast to southwest line starting from the Greater Hinggan Mts. running through the Taihang cordillera and the Snow Peak Mts. all the way to the southernmost limits of the Yunnan-Guangxi border, which spans a direct distance of about 4500 km or so (Fig. 3.1). According to Ying and Yang (1992), China’s geographical relief came into being approximately 2–3 million years ago during the Neotectonic movement of the Quaternary Period. Under the long period of interactions between the interior and exterior geological forces and processes, five major landform types were formed: mountains, hills, plateaus, basins, and plains. The mountains in China range mostly in west-east and northwest-southeast directions, while a few stretch in the northeast-southwest direction such as 49

50

3

Natural Conditions Influencing Chinese Grassland Ecosystems Legends Yangtze River

ķ

Altay Mts.

ĸ

Ņ Junggar bsn.

Ċ

ņ Tarim bsn.

Kunlun Mts.

Inner Mongolia Plateau

Qilian Mts.

ľ

Qaidam bsn.

Qinghai-Tibet Plateau

Himalayas

ĉFirst-step relief (> 4,000 m) ĊSecond-step relief (1,000-2,000 m)

Beijing

Sea of Japan

North China Plains

Ň

ċ

Ļ

Yellow Sea

East China Sea

Nyainqentanglha Ľ Sichuan bsn.

Yangtze Plains ŀ

Ł

500

ĺ

Qinling Ridge

Yun-Gui Plateau

0

Relief

Loess Plateau

ĉ

Gangdise Mts.

Nenjiang-Songhua Jiang

Ĺ NE China Plains

Tianshan Mts.

Altun Mts.

Yellow River

ń ł

Nanling Ridge

Mountains ķ * UHDWHU+ LQJJJDQ0 WVQRUWKVRXWK WUHQGLQJ  ĸ  /HVVHU + LQJJDQ Ĺ & KDQJEDLĺ7 DLKDQJĻ: XVKDQļ 6QRZ 3HDN Ľ  + HQJGXDQ ľ  + HODQ Ŀ: X\LVKDQŀ6KHQQRQJMLD Lakes Ł Dongting Lake

Ń

ļ

ċThird-step relief (< 500 m)

Ŀ

ł Poyang Lake Ń Taihu Lake ń Honghu Lake Ņ Hulun Lake

1000 km

ņ Lop Nur

South China Sea

Ň4 LQJKDL/DNH

Fig. 3.1 Outline relief and geomorphic map of China

those forming the demarcation line between the aforementioned second and the third steps, with only the Helan, Liupan, and Hengduan Mountains running in the northsouth direction. There are four large basins in the country, including the Junggar and the Tarim basins in Xinjiang, the Qaidam Basin in northern Qinghai, and the Sichuan Basin in the central part of the Sichuan Province. They occupy a total area of approximately 1.3 million km2. Large plateaus include the Qinghai-Tibet Plateau, the Inner Mongolia Plateau, the Loess Plateau, and the Yun-Gui Plateau, which together occupy a total area of some 4.64 million km2. Hills are most numerous in southeast China. Plains cover a total area of about 1.1 million km2, the best-known of which are the northeast China, North China, and Jianghan plains (Ying and Yang 1992). In addition, there are some very unique and endemic kinds of landforms in China, such as alpine glacial, permafrost, loess, eolian, volcanic, coastal, red bed, and Karst formations. Rivers, lakes, and marshes are numerous and diverse. There are presently more than 50,000 rivers each with a drainage area of at least 100 km2, of which 2000 or so are recognized as the provincial-level rivers (Yang and Zhang 1992). The endorheic rivers drain about one-third of the nation’s territory, whereas the exorheic rivers’ total drainage area comprises the remaining two-thirds. The Yangtze River (also known as the Long River or Changjiang) is the single longest river in the country, with a length of some 6300 km and an overall drainage area of 1.8 million km2. The Yellow River (Huanghe) ranks second in length (5400 km) but third

in drainage area (0.75 million km2); the Heilong River is the second largest in drainage area (0.88 million km2), but is shorter than the Pearl River (Zhujiang). There are some 24,800 natural lakes of varying sizes, of which about 2300 are over 1 km2 in surface area. Together, they occupy a total area of roughly 71,000 km2, or 0.8% of the national territory. Among the best-known natural lakes are Qinghai Lake, Poyang Lake, and Dongting Lake. In addition, some 80,000 pools and reservoirs are scattered all across the country. There are some 110,000 km of marshes, with the Sanjiang wetland in the Northeast Plains the largest, which totals about 70,000 km2 and consists of various marshes and bogs. The Zoige (Norgay) marsh is situated in northwestern Sichuan, covering a total area of some 20,000 km2, dominated primarily by peat bogs. Large tracts of marshes can also frequently be found in the two Hinggan mountainous regions, in the Tianshan (Tienshan) Mountains, in the Altay Mountains of Xinjiang, in southern Gansu, and on the Yun-Gui Plateau. As far as Chinese grassland ecosystems are concerned, the six following landform and/or assemblage types in China are the most important and relevant. They are the northeast China Plains, the Inner Mongolia Plateau, the Loess Plateau, the Xinjiang mountain-basin assemblage, the Qinghai-Tibet Plateau, and the Yun-Gui-Chuan plateau assemblage, upon which the total area of the grasslands accounts for about 85% of the nation’s total (see Table 2.1). The northeast China Plains are the largest of their kind in the country, occupying an area of about 350,000 km2 in total (Zheng et al. 1992). More specifically, the northeast China

3.1 Physical Features

51

Table 3.1 Major temperature zones and their ranges in China Temperature zone Tropical Subtropical

Cumulative temp. (
10  C) >8000 4500–8000

Frost-free days 365 220–365

Warm-temperate

3400–4500

170–220

Temperate Cold-temperate Qinghai-Tibet Plateau alpine

1600–3400 K ¼ NH4 > Na. Of particular significance are the exchange reactions between hydrogen ions and cations. Hydrogen ions can be generated by organic matter decomposition naturally, while the displaced cations and their products may precipitate and volatilize or be strongly associated with anions, which encourage the exchange reaction to proceed and produce more of these cations. Of these, the insoluble ones will deposit at the bottom of the profile, while the soluble ones such as K, Mg, and Na ions will be easily leached out of the soil system in the high rainfall regions. This explains why the soils are dominated by Al ions in the moist regions of south China while the arid and semiarid regions of north China are dominated by Ca ions. On the one hand, Al and Ca have the strongest strengths of adsorption due to their higher charges and smaller hydrated radius; on the other hand, the soil organic matter content of these southern soils is commonly too low to produce sufficient hydrogen ions to displace them. However, intensifying acid rainfall in southeast China in recent decades has substantially increased the input of hydrogen ions into the soil, which has resulted in leaching and in-depth depositions of Al ions, compounding further the deterioration trend of the acid soil in the region. Application of limestone to neutralize acid soils has a long history in China, whereby hydrogen ions may be displaced by Ca ions, released into a soil solution, and combined with oxygen atoms deriving from CaCO3 to form water. The water can dilute the soil solution and enhance CO2 volatilization out of the soil, making the aforementioned reaction process occur continually and irreversibly, thereby effectively removing the hydrogen ions from the soil solution and consequently reducing the acidity of the soil to a certain extent. Some soil colloids favor the absorption of particular cations under certain conditions. For example, owing to their specifically weathered crystalline structures characterized by abundant inter-tetrahedral spaces, vermiculite and fine mica have very high affinities for K and NH4+, which exerts significant effects on the availability of these nutrients for plant growth. Smectite absorbs calcium much more tightly than kaolinite does; humus and iron oxide colloids show highly selective affinities for certain heavy metal ions such as copper and lead, being conducive to the removal of these pollutants from soil solution. Cation exchange capacity (CEC) can quantitatively estimate the sum total of exchangeable cations that a soil can afford to absorb, which is calculated as the number of moles of positive charges adsorbed per mass unit expressed most often in centimoles of charges per kilogram soil (cmolc/kg). However, the old unit, meq per 100 g of dry soil, is more frequently used by Chinese researchers. The CEC is an

60

3

important parameter for classifying soils in many countries such as the USA and Canada. Generally, CEC decreases with increasing acidity in most soils. At a low pH level, only the 2:1 type clays and a few organic colloids, allophone, and 1:1 type clays are capable of adsorbing exchangeable ions. By contrast, at higher pH values, 1:1 type clays, allophone, and even Fe and Al oxides can hold exchangeable ions in quantities. Anion exchange is a bit special because, in addition to the fact that its adsorption method is similar to that for cations, anions can also react with surface oxides or hydroxides, giving rise to the occurrence of the inner-sphere complex. Positive charges on the surfaces of kaolinite, allophone, and iron and aluminum oxides attract and bond with SO42, NO3, etc. more tightly than Cl and OH, making them bilaterally exchangeable under certain conditions. In addition, counter to the case for cations, the anion exchange capacity (AEC) of soil usually increases with increasing acidity. In some highly acidic soils in the tropical and subtropical regions of South China, the exchange activities of anions may exceed those of cations. It should be noticed that the absorption and release of nutrient elements by plants may play a very important role in regulating the exchange processes for both cations and anions in the soil. In the future, the ion exchange process-regulating means will become a crucial technical clue in figuring out solutions for the conservation of biological nutrients, cleaning of pollutants, detoxification of pesticides, and for combating a wide variety of other soilassociated environmental issues.

3.3.2

Characteristics of the Soil Resources in China

Soil resources are extremely abundant in China. China’s total land area accounts for about 6.7% of the world’s total, being the third largest country in the world next only to Russia and Canada. Its territory covers a geographic scope extending from the cold-temperate zone to the tropics and from humid coastal areas in the east to interior arid areas in the west, within which zonal and transzonal changes in environmental conditions and biota are enormous, giving rise to the occurrence of various types of soils. According to the book “Soils of China” (SOC), 10 soil orders consisting of 48 soil types and 128 subtypes have been distinguished and assigned to Chinese soils nationwide (Xi and Gong 1987), of which the alpine soil is largest in extent, followed by the ferrallitic, eluvial (Alfisols), pedocal, and lithogenic soils as well as the rest of the soil orders (Table 3.2). Most importantly, about 75% of the land is usable in China. The soils occurring on the mountains and hills support a large proportion (about 65%), with only 35% of the country’s population found on the plains or flat lands. Geographically,

Natural Conditions Influencing Chinese Grassland Ecosystems

Table 3.2 Soil orders and their cumulative areas in Chinaa Order Ferralsol Alfisol Semi-Alfisol Pedocal Gypsici-salic soil Semi-hydromorphic soil Hydromorphic soil Saline soil Lithogenic soil Alpine soil Others Total sum a

Area (104 km2) 147.68 119.69 43.29 110.24 75.71 78.58 42.67 19.08 104.03 198.78 20.24 960.00

Prop. of the total (%) 15.39 12.47 4.51 11.49 7.88 8.18 4.44 1.99 10.84 20.70 2.11 100

Adapted from Shi et al. (1987a)

about 50% of the nation’s total land occurs on the relief above 1000 m in elevation, and 20% occurs on the mountains above 3000 m. There were some 1.38 million km2 of various arable lands in the country as of the late 1980s (Xi 1998). However, given the huge population, arable land is extremely limited in China. Moreover, the area of such land has declined to no more than 1.2 million km2 to date, a level at which only 0.1 hm2 of cropland is available for each person—barely half that of the world’s average (Liu and Diamond 2005). In addition, the distribution of the soil resources is rather unbalanced (Fig. 3.4), with about 90% of the croplands and forests lying in the eastern monsoon region, while a considerable proportion of the land is infertile and low in net primary production.

3.3.2.1 Ferralsol Order 1. Latosol (Type) (1) Orthic latosol (Subtype) (2) Dark latosol (3) Yellow latosol 2. Lateritic red earth (4) Orthic lateritic red earth (5) Dark lateritic red earth (6) Yellow lateritic red earth (7) Lateritic earth 3. Red earth (8) Orthic red earth (9) Dark red earth (10) Yellow red earth (11) Cinnamon red earth (12) Infant red earth 4. Yellow earth (13) Orthic yellow earth (14) Surface gleyed yellow earth (15) Podzolic yellow earth (16) Infant yellow earth 5. Torrid red earth

3.3 Soils

61

Fig. 3.4 Outline map of soil types of China. (Image regeneration courtesy of CY Song)

Ferralsols are found in vast quantities in the subtropical and tropical regions of South China. It comprises the most diverse kinds of soils, to which 5 soil types and 16 subtypes are assigned. Monsoonal climates prevail in these regions, characterized by abundant rainfall and high temperatures, with distinct wet and dry seasons. The mean annual temperature ranges between 16 and 25  C, the cumulative temperature above 10  C attaining 5000  C in most areas and to as high as 9000  C in the southernmost areas such as the Hainan Island. The mean annual precipitation averages more than 1500 mm, being largely balanced with evaporation. The topography is dominated mainly by low mountains and hills. All of these factors favor the strong weathering of soil parent materials and the biogeochemical cycling of nutrients, the two most important processes influencing the genesis and development of ferralsols. Red earth and latosols establish mostly on hilly tablelands where the Al-accumulating reaction is intense and occurs deep in the soil profile. Yellow earth occurs more often on the upper section of the mountains

or hills where the climate is cool but moist, with relatively weakly developed mineral substrata. By contrast, in valleys where the climate is hot and dry, the leaching process is weak, giving rise to the occurrence of torrid red earth with varied clay mineral types (Zhao et al. 1987). The Al-accumulating process, also known as the Si-losing (desilicification) process, is the most principal reaction in the genesis of red earth, whereby silicates are intensively decomposed, with Si and base ions leached out in bulk, engendering the accumulations of Al and Fe oxides in large quantities. Clays and secondary minerals are formed at the same time. The translocation rate of Si can reach 40% to 70%, while that for Ca and Mg may be as high as 100%. By contrast, the accumulation rates of Fe and Al are approximately 7–15% and 10–12%, respectively. Biological cycling of chemical elements plays a crucial role in the formation and development of ferralsols. In a tropical forest of Xishuang Banna, Yunnan, litter fall often may exceed 10 tons hm2, and the annually absorbed amount of ash elements averages

62

1852.5 kg hm2 in total, being 162.8 kg hm2 for nitrogen, 16.5 kg hm2 for P2O5, and 38.25 kg hm2 for K2O. Red earth occurs broadly in the hilly regions as well as on the low mountains located to the south of the Yangtze River’s main course. It forms under subtropical climatic and biological conditions, with the subtropical broadleaved evergreen forest being the indigenous vegetation type. Litter fall yields 3750–4500 kg/hm2 of dry weight phytomass. Fir and pine plantations are prevalent, and bamboo stands are scattered widely. Crops are harvested three times a year, with cash trees and crops particularly suitable for planting. The agricultural productivity of red earth varies greatly, depending on the location-specific soil properties. The Sito-Al ratio of typical clays ranges from 1.8 to 2.2, with clay minerals dominated by kaolinite. Parent materials have considerable influence on the properties of the soil. The various kinds of red earth derived primarily from red clays of the Quaternary Period are generally thick in depth (10 m or so), with a rather high clay content and significant sedimentation rate. However, considerable amounts of original minerals can still be found in the soil, including potash feldspar, albite, and amphibole.. Being clayey, the permeability of the soil is generally poor. The minerals developed on the red sandstone of the Tertiary Period are usually coarser, thin in depth (50–60 cm), and weak in conserving water and nutrients, with very low phosphorus but high potassium contents; that originating from granite and gneiss is found mainly on the low mountains and tall hills with elevations between 150 and 350 m above sea level, with the surface layer of gray-brown loam rich in K. Due to intensely undulating terrain and steep topography, the soil is extremely suitable for erosion. By contrast, well-developed red earth is found to occur upon limestone and basalt (a type of dark rock of volcanic origin), mostly with a clay texture. However, its distribution extent is quite limited. Vegetation shows significant effects on the nature and properties of red earth. The SOM content under forests may reach 5–6%, with that covered by tussocks varying between 1% and 2%, whereas that occurring in eroded areas being less than 1%. Latosols occur generally to the south of 22 N, mainly on Hainan Island and the Leizhou Peninsula, and partially in the Xishuang Banna region of Yunnan. Weathered materials range from several to one hundred or more meters in depth on lower terrain underlain by igneous, sedimentary, and alluvial bedrocks. They support mostly the tropical rainy and monsoonal forests. Humus of the soil is usually simple in structure, consisting primarily of fulvic acids as well as simplified forms of humic acids, depending heavily on the vegetation under which it establishes. For example, fulvic acids are more prominent than humic acids in the soil under the seasonal rain forest and the bamboo forest, but the contrary is true under the tussock grassland. In addition, soil organic matter (SOM) varies in composition with elevation;

3

Natural Conditions Influencing Chinese Grassland Ecosystems

the carbon-to-nitrogen ratio of SOM in the mountainous and hilly regions below 1500 m in elevation is generally less than 15, but may attain 15–30 in sectors over 1500 m. The content of organic matter may reach 8–10% at undisturbed sites, and the gray-brown surface soil layer can be 15–30 cm in depth. However, once cultivated, the decomposition of soil organic matter is rapid and occurs in large quantities. The slashing and burning of local natural forests for rubber plantations has caused substantial losses of nutrient elements historically in these regions. Five to six years after cultivation, more than a 40% decline of SOM has been reported (Ren et al. 2008). Yellow earth is a major soil type occurring widely in the subtropical and tropical mountainous regions of Sichuan and Guizhou. It has been formed under humid and relatively frigid, foggy, and overcast climates, which originally supported mostly the subtropical broad-leaved evergreen forest and the broadleaved evergreen and deciduous mixed forest, of which a considerable part now has been destroyed and replaced by scrubs and tussock grasslands. Unlike the Al-accumulating process for red earth, that for yellow earth is dominated by the accumulation of hydrolyzed Fe oxides and gibbsite. The Si-to-Al ratio varies more greatly in clays than in red earth. In addition, because of apparent cheluviation, the pH value of yellow earth is lower than that of red earth, whereas the amount of exchangeable Al and the hydrolytic coefficient of yellow earth are both higher than those of red earth. Parent materials underlying the yellow earth comprise mainly granite and sandstone, with scattered shale and the Quaternary red clays found at localized sites. Leaching is relatively strong in the soil, with the content of exchangeable base ions being less than 10 meq per 100 g dry topsoil. The saturation degree of base ions is usually between 10% and 30%, and the pH values range from 4.5 to 5.5. Torrid red earth, formerly called the savanna soil, comes into being under hot and dry tropical climates. It is found mainly on the southwestern Hainan Island and southern Yunnan. Under the influence of contrasting elevation differences between deep valleys and high mountains, the hot and dry winds prevail, causing low precipitation and high evaporation, with a drought period usually of 7 months. Tropical savannas or shrubby tussock vegetation are most prominent. The SOM-accumulating process is quite special for this soil. On the one hand, plants grow very vigorously in the rainy season; on the other hand, decomposition of SOM is greatly restricted during the long drought season. As a consequence, coarse SOM accumulates in large quantities, the content of which usually attains 3–4%. The soil weathering process is weak, the Al-accumulating and Si-losing processes being not obvious. However, the accumulation of Fe oxides occurs to some extent, and the content of base ions is relatively high, which reflect the soil-forming characteristics under the special climatic and biological conditions of the torrid red earth. In contrast, the lateritic red earth group is

3.3 Soils

found less abundantly in certain southern subtropical areas, being intermediate in nature and property between the red earth and latosol in almost every way.

3.3.2.2 Alfisol Order 6. Yellow-brown earth (17) Orthic yellow-brown earth (18) Yellow-brown earth with clay pan 7. Brown forest soil (19) Orthic brown forest soil (20) Albic brown forest soil (21) Cultivated meadow brown forest soil (22) Infant brown forest soil 8. Dark brown forest soil (23) Orthic dark brown forest soil (24) Meadow dark brown forest soil (25) Gleyed dark brown forest soil (26) Albic dark brown forest soil 9. Gray forest soil (27) Light gray forest soil (28) Dark gray forest soil 10. Podzolic soil (29) Orthic podzolic soil (30) Humus podzolic soil (31) Brown coniferous forest soil (32) Brown dark coniferous forest soil Alfisols, also known as eluvial soils, are found mostly in eastern China in areas with moist monsoonal climates, characterized by several leaching-associated properties, such as argillification of the soil body, unsaturated bases, and dissociated Fe ions in the soil (CNSSO—Chinese National Soil Survey Office 1998). Soil moisture regimes are generally comparable among the different soil types, while climate conditions vary from frigid to temperate, warm-temperate, and down to subtropical types with locality shifts from north to south. Along this sequence, they maintain the coniferous, coniferous and deciduous broad-leaved mixed deciduous broad-leaved, the deciduous and broad-leaved evergreen mixed, and the broad-leaved evergreen forests, respectively. Geographically, they are confined to East China, North China, and northeastern China, and also occur on the vertical spectrum of the mountains in central and southwestern China. Owing to differences in heat conditions, the leaching intensity, in terms of the degree of argillification, the degree of base saturation, and the extent to which Fe ions are dissociated, decreases significantly from south to north, with the composition in clay minerals alternating from the 1:1 only type to both 1:1 and 2:1 types and up to the 2:1 only type, correspondingly. By contrast, the soils occurring in the same heat zone generally share the same leaching properties, provided that their parent materials are identical or similar.

63

However, if the parent materials differ greatly, the soil leaching properties would differentiate to certain extents even though they are in the same climatic region. For example, the yellow-brown earth developed on loessial materials in the low mountainous and hilly regions of the subtropical Yangtze River valleys is dominated much more by 2:1 type clay minerals than those established on the neutrally acidic, rock-weathering derived parent materials. The same is true for the argillification process. In temperate regions, the alfisols formed on river and lacustrine deposits that are light in the upper section and sticky in the lower part generally have a water-impermeable, heavy-textured subsoil layer. Therefore, large amounts of reductive Fe and Mn ions produced by periodic waterlogging in the upper layer usually are leached down, of which a portion may be drained sideways by groundwater out of the soil body, while the remaining would be translocated further down along pores and crevices through the prismaticstructured subsoil. This generates depositing features such as iron flecks, Fe and Mn concretions, and colloid coatings present in the mineral soil layer. It is this process that engenders formations of the bleached horizon and the sedimentary horizon in sequence under the humus layer. By contrast, those derived from the neutrally acidic, weathered rocky parent materials have only two soil horizons, i.e., the gray-brown humus layer and the brown undersoil horizon, which is largely due to the flourishingly growing trees which generate a dense litter layer on the forest floor as well as relatively underdeveloped substrata. The alfisols formed on intermediately acidic rocky parent materials are featured by acid-leaching characteristics in that there exists a distinct litter layer, which, after being humified, usually produces the fulvic-dominated humus acids, creating an acid-leaching environment in the surface soil layer. Under this acidic status, the degree of base saturation is considerably lowered, such that portions of Fe and Al cations are exchanged into the soil solution and transferred down by water flow. However, because of the relatively short leaching period and inhibition by the frozen layer, leaching is generally weak in these areas. In addition, when the surface soil layer becomes frozen, part of the leached materials still may return to higher positions in the profile with the upwards movement of subsoil water, which would greatly narrow the differences in Si/Fe and Si/Al ratios of clay minerals throughout the soil profile. The alfisols developed on ice water-deposited parent materials at low sectors of the frigid-temperate region usually have a gray leached layer between the litter layer and the humus layer, which is generated primarily under the dualinfluences of both leaching and bleaching. The contents of Fe, Al, and Mn in this layer are all lower than those of the deposited layer, while the content of Si is usually higher than

64

in the latter layer. Most of the soil types of this order support forests and are therefore not discussed any further.

3.3.2.3 Semi-Alfisol Order 11. Cinnamon soil (33) Orthic cinnamon soil (34) Luvic cinnamon soil (35) Calcic cinnamon soil (36) Cultivated meadow cinnamon soil (37) Infant cinnamon soil 12. Stratified old matured loessial soil 13. Gray-cinnamon soil (38) Luvic gray-cinnamon soil (39) Calcic gray-cinnamon soil Semi-alfisol soils are formed under weak eluviation, characterized by the fact that although carbonates have been leached, they are not thoroughly washed out of the soil body (CNSSO 1998). They are found mostly in semiarid regions within different heat zones in China. Calcium carbonates are the primary translocated mineral compound, while Fe oxides are also slightly dissociated and deposited in the soil. Sometimes white silicon powders can be seen at the bottom horizon. In the vast limestone-outcropped or limestone-corroded areas, various kinds of corrosion-weathered limestone are seen, such as red limestone, yellow limestone, and brown limestone that all exhibit the half- or partly leached profile feature. Soil horizons are well developed, being usually of dual-horizon, comprising the humus layer in the upper section with the claying horizon underneath. Clay minerals consist mostly of 2:1 type hydromica, vermiculite, and chlorite, with kaolinite occurring only in some subtropical or tropical areas. The Si/Al ratio varies from 2.8 to 3.5. Although not significantly dissociated and accumulated, the cation exchange capacity is still relatively high, dominated by Ca and Mg ions in most cases. The pH value of the soil ranges from 6.0 to 7.5, with an increasing trend with soil depth. Three leaching-deposition types defining the semialfisol soils are generally recognized, i.e., the calciumaccumulating type characterized by apparent Ca accumulation in the surface soil owing to the partial-only leaching loss of limestone, the mixed Ca-leaching and accumulating type wherein no limestone nor claying horizon is seen in the surface soil while Ca accumulation is apparent underneath, and the leaching out type wherein Ca deposits are not found at all within a one meter soil depth in the profile, but bases are saturated.

3.3.2.4 Pedocal Order 14. Dark loessial soil (40) Orthic dark loessial soil (41) Argillic dark loessial soil (42) Light-textured dark loessial soil (43) Rusty dark loessial soil

3

Natural Conditions Influencing Chinese Grassland Ecosystems

15. Chernozem (44) Orthic chernozem (45) Luvic chernozem (46) Meadow chernozem (47) Surface podzolic chernozem 16. Chestnut soil (48) Dark chestnut soil (49) Light chestnut soil (50) Orthic chestnut soil (51) Meadow chestnut soil 17. Brown soil (52) Orthic brown soil (53) Light brown soil (54) Meadow brown soil (55) Sandy infant brown soil 18. Sierozem (56) Orthic sierozem (57) Meadow sierozem (58) Irrigation sierozem The pedocal order is zonal in distribution, occurring primarily in the mid-temperate and warm-temperate sub-zones of north China, and is found mostly in the semiarid and arid regions of Inner Mongolia, Ningxia, Gansu, and Xinjiang. Of the order, chernozem, the chestnut soil, and the brown soil are most widely and predominantly distributed. The zonal distribution pattern of the different soil types is basically consistent with those for vegetation, biota, and climate. The chestnut soil belt lies between the chernozem belt on its east and the brown soil belt on its west, each of which display a northeast to southwest bow-shaped extension, which primarily support temperate steppes. The principal process in the formation of the pedocal soils is the accumulation of calcium-rich organic matter, which derives largely from the dense roots of steppe plants, forming the thick epipedoncharacterized soils of this order (CNSSO 1998). Dark loessial soil is a type of cultivated soil with a distinct black, deep loessial horizon. In situ claying is commonly seen in the soil body. Climate in the dark loessial soil region is warm-temperate and semiarid, with the mean annual temperature of 8–10  C and mean annual precipitation from 300 to 500 mm. It is usually found interspersed in cultivated regions of the yellow loessial soil on the southern Loess Plateau, occurring most often on flat lands or gentle slopes, with a cumulative area totaling a bit more than 10,000 km2. Crops such as wheat, corn, millet, sorghum, and soybean are commonly grown on this soil. Originally, it had supported expanses of natural grasslands, which currently are merely scattered on roadsides or around crop fields with a very limited cumulative area. Dark loessial soils commonly have a relatively deep humus layer (about 1 m in depth), whereas soil organic matter is somewhat scarce, the content of which is only 1–1.5%. Argillification generally is weak, mostly

3.3 Soils

without a distinct claying horizon in the soil profile. By contrast, Ca accumulation is more intensive, with limestone accumulating considerably and showing a hypha-shaped configuration in the soil body. Because most soluble base cations have been leached out, there is no salination occurring. The profile is characterized top-down by a mature layer 20–30 cm in depth, an old tillage layer 10–15 cm in thickness, a dark loessial horizon 50–80 cm in thickness, a limestoneaccumulated layer 150 cm in thickness, and the parent material horizon 200 cm or so in thickness. Coarse silts dominate the soil texture, which account for more than half of the total particles, while clays make up only 15–20%. The soil is rather loose and porous in structure, with rich microaggregates, thereby allowing ease of cultivation. The content of limestone ranges from 7% to 17%, of which 90% is in the form of calcium carbonates, while the remaining is in the form of magnesium silicates. Its cation exchange capacity varies between 9 and 14 meq per 100 g dry soil, the nitrogen content being 0.03–0.1%; that of total phosphorus ranges from 0.15% to 0.17%, mostly being insoluble calcium phosphates; potassium is quite rich in the soil, varying between 1.6% and 2.0%; the SiO2/Al2O3 ratio averages 3.43. Chernozem is found mainly on the eastern and western piedmonts of the middle and southern sections of the Greater Hinggan Mountains and is partially scattered on the flat highlands of the Song-Nen Plain. It mainly supports the meadow steppe and meadows. This soil is a product of the interaction between the humus-accumulating process and the deposition process of leached limestone. The profile consists of the humus layer, the leached, tongue-shaped humus layer, the Ca-accumulated horizon, and the horizon of parent materials. The humus layer is generally 30–50 cm in thickness, whereas the Ca-deposited layer occurs most often at a depth from 50 to 90 cm in the soil. The leached humus layer is specific to chernozem, which lies between the humus layer and the Ca-accumulated layer. Major parent materials underlying chernozem are generally loessal materials; hence, it is intermediate in texture between the black soil and the chestnut soil, with 30–60% silts and 10–35% clays in particle composition. Leaching intensity varies among the subtypes and generally occurs in the following decreasing order: Luvic chernozem (maximal Ca accumulation occurring at 1.5 m in depth) > orthic chernozem (1 m in depth) > meadow chernozem (40 cm in depth) > surface podzolic chernozem (10 cm in depth), with the maximum content of calcium oxides being 6%, 8%, 16%, and 7%, respectively, while the content of SOM of the surface layer soil is roughly 10%, 5–8%, 5–7%, and 42 >36 >34 >43 >50 >53

Note: aW western section, M middle section, E eastern section, N north slope, S south slope; bD desert, MDS montane desert steppe, MTS montane typical steppe, MMS montane meadow steppe, MM montane meadow, AS alpine steppe, AM alpine meadow, CV cryophilous vegetation. (Adapted from Xü et al. 1993)

forest stands directly at times. It is discontinuously distributed on its vertical belt on the Tianshan, Altay, and Junggar-surrounding mountains, varying considerably from section to section of the same mountain range. In the Altay Mountains, it occurs at altitudes from 1400 up to 1700 m in the east and from 1700 to 2000 m in the west. On the Tianshan Mountains, it usually appears on northern slopes at altitudes from 1600 to 1800 m in the western section and from 1800 to 2200 m in the eastern section; by contrast, on the mountains around the Junggar Basin, it is found at altitudes from 1800 to 2000 m in the west and from 2100 up to 2500 m in the east. The montane typical steppe is distributed mainly in the Altay and Ili mountainous areas of Xinjiang and sections of the Qilian Mountains stretching in the territories of Qinghai, Gansu, and Xinjiang. On the Altay Mountains, it occupies an altitudinal range from 1100 to 1600 m in the west and ascends to 1200–1900 m in the east because of increased drought. In the middle section of the Yinshan Mountains, it is found at altitudes from 1000 to 1800 m; on the Langshan and Helan Mountains, its position ascends to 1900–2000 m, approximate to the summit; on the Qilian Mountains, it occurs at altitudes from 2000 to 2500 m in the eastern section and up to altitudes from 3000 to 3500 m in the western section due to increased aridity. By contrast, in the eastern section of the Tianshan Mountains, it ranges from 1900 up to 2700 m on the northern slopes and from 2400 to 2600 m on the southern slopes. The montane desert steppe is confined mainly to the desert-based mountains, just above the steppic or montane

deserts on the vertical spectrum. It is found on the Langshan, Helan, and western Qilian Mountains in the eastern part of the Chinese desert region, on the Beita and Altay Mountains in the north, on the Tianshan Mountains and the mountains to their east in the central region, and on the subalpines of the Kunlun and Altun Mountains in the south. The lower limit of each montane steppe subtype generally ascends with decreasing latitude from the Altay region in the far north to the Altun Mountains in the south (Table 10.2). In addition, with increasing altitude on the mountains, the vegetation sequence consists basically of the desert, steppic desert (not shown in the table due to having been included in the desert), the montane desert steppe, the montane typical steppe, the montane meadow steppe, the alpine steppe, the alpine meadow, and the cryophilous vegetation.

10.2

Climate

The zone where the montane steppe occurs lies in one of Earth’s most interior regions, namely the central portion of the Eurasian continent. The climate belongs to the hyper-arid continental desert kind, characterized by intense solar insolation, substantial diurnal, inter-month and interannual temperature variations, and severe drought, as well as frequent windy, dusty, and stormy days. In addition, the climate varies greatly from area to area and from the plains to the mountains in particular, posing profound impacts on the occurrence and distribution pattern of the montane vegetation.

310

The montane steppe is characterized by large and rapid temperature changes. The annual sunshine length ranges from 2550 to 3500 h, with solar radiation rates from 543.3 to 647.9 kcal cm2 year1, of which 250.8–292.6 kcal cm2 year1 is photosynthetically effective. The annual accumulated temperature ranges from 4000 to 5500
C in the south, from 3100 to 3900
C in the central portion (the Junggar region), and from 2200 to 2900
C in the Altay region. The frost-free season varies between 180 and 220 days in the south and between 140 and 185 days in the north. Mean annual temperatures range from 9.8 to 13.9
C in the Tarim-Turpan-Hami region, between 5.0 and 7.5
C in the Junggar Basin, and from 2.5 to 5.0
C in the TachengAltay region. However, these values have mostly been measured on the plains. The mean annual temperature in the mid-altitude belt of the large mountain ranges is typically below 3
C. The maximum monthly temperature occurs in July and the minimum occurs in January, with ranges from 20 to 27
C in July and from 17 to 6
C in January. The day and night temperature ranges are 13–16
C in the south and 12–14
C in the north, with 44.2
C recorded in Minfeng County, Xinjiang. The maximal inter-month temperature difference within a year is generally 40
C or so in the north and 30–35
C in the south. Generally, the mean annual precipitation is greater in the north than in the south. It ranges from 600 to 800 mm in Altay, from 500 to 600 mm on the northern slopes and 300 to 400 mm on the southern slopes of the Tianshan Mountains, and from 300 to 400 mm on the northern slopes of the Kunlun Mountains. Interannual variations in precipitation are considerable, with the CV (coefficient of variation) mostly between 30 and 50% across the entire zone. Annual evaporation rates range from 1000 to 2500 mm. The heavily windy period averages 42 days in the north, with roughly 30 days of sandy-dusty weather annually. The montane meadow steppe generally occurs along a belt where the precipitation is between 350 and 450 mm, the aridity is between 0.7 and 1.2, and the annual cumulative temperature is between 1500 and 2200
C. The climate of the montane typical steppe is generally warmer but less humid, with the annual precipitation ranging from 250 to 350 mm and the annual cumulative temperature (10
C) from 2000 to 2500
C. By contrast, the montane desert steppe, lying lowest on the vertical gradient, is climatically characterized by the lowest amount of precipitation (150–300 mm) and the highest amount of heat, with a mean annual temperature of 2–4
C and a cumulative temperature of 2000 to 3000
C (Table 10.3).

10

Montane Steppe Ecosystem

Table 10.3 Climatic parameters for major montane steppe areas listed from north to south Area Altay WM WL MidM EM Tacheng Junggar L MidM Tianshan N CJH Urumqi XQZ YWZ S Alataw M Balikun L M Ili Tarim Yining Kunlun N WS ES Chele

MAT (
C) 2 to 4 4 0–4.0

Jan. (
C)

Jul. (
C)

19.5 15.2 10.7 15.9

25.7 27.7 15 4.8

2.5–5.0 5.0–7.5

5.8 7.3 2.1 5.4

5–8 9.8–13.9 2.8 7 to 10

MAP (mm) 600–800 200–350 500 400 130–280 200–250 500–800 500–600 128 194.6 525.9 443.8 300–400 300100–250 300–500 1000 40–60 257.5 300–400 30–50 60–70 500

Abbreviations: MAT mean annual temperature, MAP mean annual precipitation, W western section, E eastern section, N north slope, S south slope, M mountain, L lower mountain, Mid mid-altitude, CJH Caijiahu (441 m), Urumqi (902.7 m), XQZ Xiaoquzi (2160 m), YWZ Yunwuzhan (3539 m). (Adapted from Xü et al. 1993)

10.3

Soils

Xinjiang montane steppe soils are found principally in the vertical spectrum of major mountains and vary substantially in terms of soil type and properties with the aspect, slope, topography, and vegetation of the mountain in question. The Altay Mountains have the most complete and representative sequence of soils along their vertical gradient, consisting of, from foothill to mountaintop, the montane brown soil supporting the steppic desert, the montane chestnut soil underpinning the montane desert steppe and the typical steppe, chernozem nourishing the montane meadow steppe, the subalpine meadow soil bearing montane and subalpine meadows, the alpine meadow soil instrumental to the occurrence of the alpine meadow, and the high-altitude icy bog soil associated with the alpine tundra (Xü et al. 1993). By contrast, some of the aforementioned soil types may be absent on

10.3

Soils

311

Table 10.4 Physiochemical properties of montane typical steppe soils collected in different areas Site NG

BN

AS

D (cm) 0–17 17–48 48–66 66–115 0–9 9–23 23–42 42–80 80–104 104–120 0–20 20–50 50–110

pH 7.6 7.7 8.2 8.2 8.4 8.2 8.3 8.2 8.4 8.6 8.2 8.4 8.3

CaCO3 (g/kg) 15.3 11.1 10.2 7.3 3.2 3.2 3.6 3.0 120.8 152.7 130.0 210.0 163.0

SOM 21.7 23 11.2 14.3 17.2 7.9 5.2 4.7 4.9 4.9 20.3 12.5 7.8

TN 1.48 1.48 0.85 0.99 1.05 0.49 0.50 0.48 0.41 0.39 1.04 0.84 0.47

TP 0.69 0.60 0.53 0.52 0.58 0.52 0.49 0.45 0.41 0.44 0.77 0.55 0.72

TK 15.1 18.4 18.1 19.9 17.1 17.1 18.2 18.4 16.6 24.4 18.5 17.5 18.5

CEC (me/100 g) 15.6 15.6 13.2 15.4 11.0 9.6 9.4 8.4 5.6 4.4 6.7 8.9 7.7

Particle (mm, %) >0.02 0.02 0.02 94.8 76.0 94.0 94.5

20 cm 98.6 161.1 129.2

2702.0 1961.0 1371.2 2073.3

1148.9 1397.8 1885.4 861.0 651.7 2573.8 1784.2 1175.4

3566.5 2318.3 3013.3 2559.7 4746.9 4572.1 6402.0 5172.0 4888.6

Total 1136.1 1641.7 1576.4

6.87 10.59 11.43 12.08

9.38 15.45 20.67 11.46 4.94 16.26 12.49 3.23

R/Ce

Sun et al. (2009) Peng et al. (2011)

Ma (2009)

Wang et al. (2014a)

Wang et al. (2008)

Source Sun et al. (2015b)

322 10 Montane Steppe Ecosystem

Montane rangeland Rhododendron spp. Polygonum vivip. Kobresia capillifolia Stipa aliena Qilian Mts. steppe

Festuca ovina Stipa capillata Carex turkestanica Stipa purpurea

North slopes 97
200 –102
130 E 37
280 –39
490 N 2861–3445 m

Tianzhu, Gansu 37
400 N, 108
320 E 2930–3200 m

Qilian Mts. 38
320 N, 100
170 E

Xiejiagou, Tianshan north slope 1620 m 40
550 N, 81
030 E

3.1 to 3.6
C 254–500 mm

0.1
C 416 mm 1430.4 mm

1.5
C 290–467.8 mm 1051.7 mm

3.3
C, 362.4 mm, 1684 mm, 120 days

0–30

0–40

0–50

AM w MMx MMS y TS z DSaa

FS LG MG HG CK LEo CK SEp RhSq PolSr KobSs SAPt PAPu AAPv

31.7 78.1 46.7 42.8 11.0

245.4 316.6 187.4 299.1 1647.1 548.4 373.0 535.8 948.2 1219.0

1269.6 992.9749.5 478.7

379.9 848.1 430.1 464.3 119.3

2279.9 3467.4 1890.1 902.2 2378.9 2909.9 2029.2 2587.3 10936.8 6159.9 5497.9 3739.3 2503.8 290.4

11.98 10.86 9.21 10.85 10.85

1.80 3.49 2.52 1.88 9.69 9.19 10.83 8.65 7.80 10.29 13.65 5.98 2.48 0.24

Huang et al. (2011)

Hu et al. (1994)

Wang et al. (2014b)

Sun et al. (2015a)

i

Note: aD depth, bTM treatment, cCB canopy biomass, dRB standing crop of root biomass, eR/C root-to-canopy biomass ratio, fLG lightly grazed, gMG moderately grazed, hHG heavily grazed, Alchemilla, jQHL Qinghai Lake, kFR free ranging, lFS fenced stand, mNS normal stand, nOG overgrazed, oLE long-term enclosure, pSE short-term enclosure, qRhS Rhododendron capitatum stand, r PolS Polygonum viviparum stand, sKobS Kobresia capillifolia stand, tSAP semi-artificial pasture, uPAP perennial artificial pasture, vAAP annual artificial pasture, wAM alpine meadow, xMM montane meadow, yMMS montane meadow steppe, zTS typical steppe, aaDS desert steppe

10

9

8

7

10.7 Fauna 323

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Table 10.11 Species and habitats of wild mammals in the Gannan region, Gansu Species Equus kiang Cervus elaphus Cervus albirostris Moschus sifanicus Bos grunniens Pantholops hodgsoni Capricornis sumatraensis Ovis ammon Panthera uncia

Habitat Grassland Forest steppe Forest steppe Scrub Grassland Alpine grassland Shrubby forest Alpine rock belt Alpine rock belt

Table 10.12 Abundance and distribution of Canis lupus in China Province Inner Mongolia Tibet Gansu Qinghai Xinjiang Others Total

Extent (km2)

126,300 908,000

Density (head/km2) 0.0009 0.0047 0.1010 0.0086

Abundance (head) 600 4000 4000 13,000 7500 5900 35,000

After Zhang et al. (2009b)

Table 10.13 Dietary composition of Canis lupus ranging in Mount Kalamaili Ungulate Nature Reserve, Xinjiang Component Equus przewalskii Equus hemionus Gazella subgutturosa Ovis ammon Vulpes corsac Horses Sheep Goats Cattle Camels Hares Birds Gerbils Jerboas Hamsters Reptiles Insects Plants Garbage Total

Summer (n ¼ 172) O RF (%) Ord. 9 1.92 8 7 1.50 11 12 2.56 7 9 1.92 8 2 0.43 15 9 1.92 8 3 0.64 13 1 0.21 16 – – 19 1 0.21 16 3 0.64 13 7 1.50 11 96 20.51 2 26 5.56 5 39 8.33 4 26 5.56 5 71 15.17 3 146 31.20 1 1 0.21 16 468 100.00

Autumn (n ¼ 106) O RF (%) Ord. 2 0.65 12 8 2.61 10 12 3.91 7 4 1.30 11 – – 17 9 2.93 8 2 0.65 12 1 0.33 15 – – 17 2 0.65 12 – – 17 9 2.93 8 54 17.59 2 16 5.21 6 43 14.01 3 22 7.17 5 34 11.07 4 88 28.66 1 1 0.33 16 307 100.00

Abbreviations: n number of scat samples, O occurrence (number of scat samples in which a dietary component was found), RF relative frequency of occurrence, Ord. order of relative frequency. (After Dong et al. 2015)

Montane Steppe Ecosystem

Table 10.14 Abundance and distribution of Ovis ammon in China Province Tibet Gansu Qinghai Xinjiang Others Total

Extent (km2) 4357 34,500 712,300

Density (head/km2) 0.0819 0.0560 0.1040 0.0627

Abundance (head) 9000 15,000 3600 35,500 900 64,000

After Zhang et al. (2009b)

10.7.2 Amphibians and Reptiles On the Helan Mountain steppe and meadow grasslands, Coluber spinalis, Rhabdophis tigrinus lateralis, and Elaphe dione are the most common snakes, while Eremias argus, E. multiocellata kozlovi, and E. vermiculata are the common lizards (Zhao 1993). In this region, the montane desert steppe occupies a vertical belt from 1400 to 1600 m, while the meadow steppe covers the belt from 1600 up to 2000 m. Wang et al. (2010) listed two species of true frogs, one toad species, one species of gecko, four species of wall lizards, three species of toad-headed lizards, six species of colubrids, one species of venomous snakes, and one species of nonvenomous snakes (Eryx miliaris) as having ranges in the Helan Mountain region (Table 10.15). Comparisons with the species of Inner Mongolia and Ningxia indicate that most species enter the Helan Mountain region from these two regions. However, the herpetofauna of the Helan Mountains differs significantly from that of the Xinjiang montane steppes.

10.7.3 Avifauna In the Altay region of Xinjiang, a total of 173 species plus 11 subspecies of birds have been recorded; they belong to 97 genera, 41 families, and 18 orders and nearly half inhabit montane forests. Zoogeographically, 95% of the species belong to the Palaearctic realm. Many of them are European-Siberian species, and many of the breeding bird species have reciprocal substitute species in mountainous areas of northeast China such as the Greater Hinggan Mountains. However, only 11 species have been observed in the montane meadow steppe belt, with Lagopus mutus nadezdae, Perdix hodgsoni koslowi, Columba rupestris turkestanica, and Leucosticte arctoa arctoa as the permanent residents. 92 species occur in the low mountains dominated by shrubby rangelands, with 26 being permanent residents, including Falco tinnumculus, Alectoris graeca dzungarica, Tringa hypoleucos, Columba livia neglecta, Bubo bubo yenisseensis, Calandrella cinerea lougipenuis, Oenanthe deserti atrogularis, Cettia cettia albiventris, three species of Parus (tits), and four species of Passer (sparrows) (Xiang and

10.7

Fauna

325

Table 10.15 Species list of amphibians and reptiles ranging in the Helan Mountains Species Anura

Bufonidae Ranidae

Squamata

Gekkonidae Agamidae

Lacertidae

Serpentiformes

Viperidae Boidae Colubridae

Bufo raddei Rana chensinensis Pelophylax nigromaculatus Alsophylax pipiens Phrynocephalus przewalskii P. frontalis P. versicolor Eremias argus E. przewalskii E. vermiculata E. multiocellata Agkistrodon intermedius Eryx miliaris Psammophis lineolatus Coluber spinalis Rhabdophis tigrinus Elaphe mandarina* E. carinata* E. dione

DV 0.0520 0.5125 0.0018 0.0018 0.0681 0.0179 R 0.1864 R R 0.1147 0.0036 0.0018 0.0090 0.0108 0.0090 0.0018 0.0036 0.0054

AC +++ +++ + + +++ +++ + +++ + + +++ + + ++ ++ ++ + + +

ZGR NE, NC NE, NC MS CA STP STP CA NE, NC CA CA CA CA CA CA PA MS SC SC PA

Abbreviations: DV dominance value, R recorded, AC abundance class, ‘+++’ abundant, ‘++’ common, ‘+’ accidental, ZGR zoogeographic region, NE northeast, NC North China, MS monsoonal, CA central Asia, STP steppe, PA palaearctic, SC south China. (After Wang et al. 2004) Table 10.16 Diet composition of certain avian species ranging in Xinjiang Species Lag. mutus P. hodgsoni Columba livia C. rupestris L. arctoa arctoa F. tinnumculus A. graeca T. hypoleucos B. bubo (owls) Cal. cinerea O. deserti Cettia cettia Parus spp. Passer spp.

Diet Catkins, berry Locust, beetle, moth, seed Fruit, seed Fruit, seed Seed, green organs Grasshopper, rodent, bird Seed and leaf of grass, seed and fruit of Rosa Ground beetle, leaf beetle, ants, crane flies Frog, toad, lizard, snake Beetle, seed Grasshopper, boll weevil Ground beetle, flies Dung beetle, bee, leaf beetle, leaf hopper, larvae of butterflies, moth Cicadas, aphid, plant hopper, leaf hopper, shield bug, ant, bee, beetle, spider

After Huang et al. (1986)

Huang 1986). The dietary composition of some of these species is presented in Table 10.16. Liu and Wang (1987) listed 43 species of birds as having ranges within the eastern section of the Qilian Mountains, of which 37 are passerine species and 20 species are permanent residents. The body weight of 32 of the species is below 50 g, with only 6 above 100 g; 22 are insectivores, 10 being phytophagous, and the rest being omnivorous; 17 species nest on the ground, 2 in crevices or breaks of rocks, 8 in

tree holes, 11 in the canopy of trees or bushes, and 5 in abandoned dens of other animals (Table 10.17). The mean standing crop biomass of the birds was estimated at 725.8 g/ hm2 in a broad leaf forest (with 18 bird species and a density of 14.35 ind./hm2), followed by 535.7 g/hm2 in a spruce forest (14 spp. and 14.85 ind./hm2), 170.0 g/hm2 in a subalpine shrubby tussock pasture (10 spp. and 9.2 ind./hm2), 166 g/hm2 in a montane meadow steppe (3 spp. and 7.65 ind./hm2), and 142.9 g/hm2 in a mixed forest stand (21 spp. and 6.98 ind./hm2). The Helan Mountains are north-south ranging with altitudes from 2000 to 3000 m, characterized by a typical continental climate. They are regarded as a natural divide between the desert steppe region and the desert zone. Various montane steppes occur predominantly at the vertical range from 1400 to 2000 m, including the generalist montane steppes at the lower belts and the shrubby steppe just above, while the montane forest and the subalpine meadow occupy the upper belts above 2000 m. Jia and Zhang (2014) listed 56 species of birds which could be expected to occur in the area. Of these, 20 odd species inhabit steppe stands permanently, of which Alectoris chukar, Columba rupestris, Parus major, Pica pica, Corvus macrorhynchos, and Falco tinnunculus are most abundant, Aegithalos caudatus, Turdus ruficollis, Tichodroma muraria, and Falco amurensis are the common species, and Milvus lineatus, Accipiter nisus, Falco amurensis, Columba livia, Picoides major, Rhopophilus pekinensis, and Emberiza spp. are relatively less numerous but still fairly important species. Yuan (2005) revealed

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Table 10.17 Species composition and community characteristics of birds ranging in the Qilian Mountains Species Accipiter nisus nisosimilis Bonasa sewerzowi Ithaginis cruentus beicki Crossoptilon auritum Phasianus colchicus Dendrocopos major beicki Calandrella acutirotris tibetana Motacilla cinerea M. alba leucopsis Anthus roseatus A. hodgsoni hodgsoni Lanius tephronotus tephronotus Cyanopica cyana kansuensis Corvus monedula monedula Cinclus pallasi Prunella strophiata strophiata Phoenicurus ochruros rufiventris Ph. hodgsoni Ph. frontalis Ph. schisticeps Tarsiger hyperythrus Saxicola torquata przewalskii Chaimarrornis leucocephalus Garrulax davidi experrectus G. ellioti Phylloscopus affinis Ph. armandii armandii Ph. inornatus mandellii Ph. proregulus proregulus Regulus regulus japonensis Lophobasileus elegans Parus major artatus P. rubidiventris beavani P. montanus affinis P. superciliosus Sitta villosa Certhia familiaris bianchii Carpodacus pucherrimus argyrophrys C. thura dubius C. erythrinus roseatus Emberiza leucocephala E. spodocephala sordida E. cia godlewskii

Dens. 0.002 0.012 0.007 0.003 0.015 0.002 0.040 0.005 0.052 0.032 0.055 0.008 0.030 0.013 0.002 0.028 0.047 0.002 0.017 0.042 0.020 0.008 0.022 0.028 0.012 0.073 0.107 0.452 0.038 0.155 0.066 0.015 0.033 0.058 0.013 0.013 0.008 0.012 0.023 0.028 0.073 0.030 0.333

RA 0.10 0.59 0.34 0.15 0.74 0.10 1.97 0.25 2.56 1.57 2.71 0.39 1.48 0.64 0.10 1.38 2.31 0.10 0.84 2.07 0.98 0.39 1.08 1.38 0.59 3.59 5.26 22.23 1.87 7.62 3.19 0.74 1.62 2.25 0.64 0.64 0.39 0.59 1.13 1.38 3.59 1.48 16.38

BW 150.0 362.5 550.0 1650.0 887.0 75.0 29.3 17.5 22.5 51.5 23.8 48.0 80.0 189.0 59.5 16.2 21.3 20.0 16.0 17.6 10.5 14.0 39.0 58.0 66.0 6.3 13.0 8.3 6.0 7.8 7.0 12.0 12.0 11.2 12.7 10.0 8.5 19.0 28.2 16.0 27.0 18.0 22.2

D B P P P P I O I I O O I O O IF O I I I I I I I O O I I I I I I I I I I I I S S S S S S

Nest TC G G G G TH G G G G G TC TC TH,RC RC TC ABH ABH ABH ABH G G RC Bush Bush Bush Bush G G TC TC TH TH TH TH TH TH G G G G Bush G

LF R R R R R R R S S S S S R R S R S R S R S S S R R S S S S S S R R R R R R S R S S S R

Abbreviations: Dens. density (ind./hm2), RA relative abundance (%), BW body weight (g), D diet, B bird, P plant, I insect, O omnivorous, F fish, S seed, TC tree canopy, G ground, TH tree hole, RC rock crevice, ABH abandoned burrow hole, LF life-form, R permanent resident, S seasonal migrant. (After Liu and Wang 1987)

significant differences in the summertime community structure of birds inhabiting several different-altitude habitats in the Helan Mountains Nature Reserve of Ningxia (Table 10.18). Tianzhu montane grasslands are distributed within a pivotal area connecting the QT Plateau, the Loess Plateau, and

the Mongol Plateau. Song et al. (1985) observed 103 species and/or subspecies of birds during several field surveys of five vertical belts of the same region in the mid-1980s. However, the total number has increased to 150-odd species to date (Qu et al. 2016). Of these, 89 are permanent residents and 52 are migratory summer breeders. In a shrubby tussock

10.7

Fauna

327

Table 10.18 Comparison of avian community traits among different habitats on the Helan Mountains Habitat Steppe Woodland Conif. forest Subalp. mdw

R 56 51 21 6

B 3.54 3.32 1.92 0.25

E 0.85 0.80 0.46 0.06

D 16.68 13.31 1.70 0.07

Table 10.19 Dominant species of rodents in the Altay region, Xinjiang Order Lagomorpha

Family Leporidae

Rodentia

Ochotonidae Petauristidae Sciuridae

Abbreviations: R richness (number of species), B biodiversity index, E evenness index, D density (ind./hm2); mdw meadow. (After Yuan 2005)

rangeland occurring at altitudes from 3000 to 3700 m, Phylloscopus affinis, Carduelis flavirostris, Carpodacus pulcherrimus, Perdix hodgsoniae, and Phasianus colchicus are most abundant, while Columba spp., Alauda arvensis, Passer montanus, and Eremophila alpestris are most common in the higher-elevation meadow steppe, with 24 and 14 breeding species observed in the two belts, respectively (Song et al. 1985).

Castoridae Dipodidae

Muridae Cricetidae

10.7.4 Rodents Roughly 60 species of rodents have ranges in the various ecosystems of northern Xinjiang (Ma 1981). The species composition of rodents in this region is rather complicated. Some 20 Mongolian Plateau species are usually present in the Junggar Basin as well as on the mountains and the Gobi to its east, while the remainder are all western desert and desert steppe species. Due to the geographic isolation caused by the Tianshan Mountains, the species that commonly occur in the Tarim Basin are rarely found in northern Xinjiang. In the Tacheng basins and Ili valleys to the west of the Tianshan Mountains, species of the Kazakhstan element are more often encountered. It is estimated that some 25 rodent species may have ranges in the montane desert steppe and typical steppe in this region (Table 10.19) (Adker 2011). The common species comprise Cardiocranius paradoxus, Euchoreutes naso, Salpingotus crassicauda, Lagurus luteus, Phodopus roborovskii, Myospalax myospalax altaicus, Spermophilus dauricus, and Meriones unguiculatus. The following rodents are the most principal pest species in the northern Xinjiang grasslands. Lagurus luteus inhabits desert steppe pastures of sages in the piedmont areas of the Altay Mountains. They inhabit a range of 4.24 million hm2, within which the destroyed area may amount to 2.0 million hm2 during outbreaks. Daily intake of dry herbage averages 30 g per individual, the average density of which was 100-odd individuals per hm2 during the period from 1985 to 2005. However, the population size fluctuates substantially from year to year. Rhombomys opimus is distributed in edge habitats in the northern areas of the Junggar Basin, occupying mainly desert rangelands. The

Species Lepus capensis L. timidus Ochotona pallasi Pteromys volans Sciurus vulgaris Eutamias sibiricus Citellus erythrogenys C. undulates Marmota bobac Castor fiber Allactaga sibirica A. elater Dipus sagitta Apodemus sylvaticus Mus musculus Cricetulus migratorius Meriones tamariscinus M. meridianus Rhombomys opimus Myospalax myospalax Ellobius talpinus Lagurus luteus Microtus arvalis M. oeconomus Ondatra zibethicus

After Adker (2011)

daily intake is about 90 g dry herbage per individual, with 10–40 kg dry plant materials per hole cluster stored in summer and fall. The density of hole clusters averages 26 per hm2. Meriones meridianus inhabits desert rangeland stands and desert steppe pastures. It typically shares habitats with R. opimus and dwells in the abandoned holes of Lagurus luteus. Ellobius talpinus commonly occupies valley meadows and desert steppe pastures. As a terricolous rodent, it gnaws on the rhizomes of Festuca, Poa, and Carex plants, and may create clusters of mounds 0.1–0.15 m2 in size within fields, which are particularly harmful to mowed meadows. Marmota bobac is the largest-sized rodent in this region, distributed widely in the montane steppes at altitudes from 300 to 1200 m where the soil is humid. It feeds mainly on sedges and grasses, either leaves, shoots, or roots, and is a major disease-carrying species. Citellus erythrogenys feeds on a variety of herbs and shrubs such as sages, grasses, and Chenopodiaceaen plants (Adker 2011). About 2.0 million hm2 of the Ili grasslands are inhabited by rodents. Out of this total area, 22.78% is stricken with pest rodents. Some 29 rodent species are recognized within the entire region, with Ellobius talpinus, Citellus relictus, C. undulates, Microtus arvalis, Meriones tamariscinus, and M. meridianus most predominant in the montane pastures (Li et al. 2000). The eastern montane steppes share most of

328

the aforementioned rodent species with the northern montane steppes, with Lepus capensis, Ochotona pallasi, Cricetulus spp. and Alticola spp. present more exclusively here (Hou and Ma 1998). Twenty-five species in eight families of rodents occur in the Tianzhu montane steppe of Gansu (Li et al. 2001). Myospalax baileyi, Marmota himalayana, Ochotona thomasi, O. macrotis, and Cricetulus migratorius are the common species in the montane meadows at altitudes above 2700 m, whereas O. davurica, Marmota himalayana, Meriones unguiculatus, Allactaga sibirica, and Cricetulus migratorius are most prominent in the montane steppes at altitudes from 2500 to 3000 m. The O. davurica + Citellus alaschanicus + Meriones unguiculatus community occurs in the montane steppe dominated by Stipa krylovii, Artemisia frigida, Aster altaicus, and Agropyron pectiniforme; the M. unguiculatus + L. capensis + Allactaga sibirica community is widespread in hilly and flat steppes consisting of S. brevifolia, Artemisia dalailamae, and Achnatherum splendens; the Cricetulus longicaudatus + O. cansus community mainly occupies Kobresia meadows. Roughly 39.1% of the total grasslands (0.4 million hm2) in this region have been infested to varying extents by rodents, with the annual vegetation loss accounting for 6.7% of the total herbage yield, resulting in an overall loss equivalent to the total annual amount of vegetation needed to feed 23,600 sheep. In the montane steppes and meadows on the midsection of the Qilian Mountains in Gansu, 36 rodent species are recorded (Wei et al. 1999). The species composition differs significantly from that of the Tianzhu montane steppe, with more temperate steppe and desert elements present here. Exclusively distributed in this region are Lepus oiostolus, 6 Ochotona spp., Citellus alaschanicus, Marmota himalayana, Cardiocranius paradoxus, Euchoreutes naso, Salpingotus kozlovi, Sicista concolor, Petaurista xanthotis, 2 Cricetulus spp., Phodopus roborovskii, Meriones unguiculatus, Microtus fuscus, Alticola argentatus, Myospalax fontanieri, and M. baileyi, with Meriones spp., Myospalax spp., and Cricetulus spp. most dominant in various kinds of the montane steppe. The rodent community of this region is distinctively characterized by the following aspects: firstly, the species composition is highly specific to the kind or type of steppe. Dominant and subordinate species differ substantially among habitats and usually come from different families or taxonomically distinct genera; secondly, the sole dominant species is overwhelmingly dominant. For example, the proportional abundance accounted for by a relevant sole dominant population generally was between one-third to one hundred percent, averaging 56.9%, in the 8 rodent communities examined by Wei et al. (1999). Ochotona curzoniae infests mainly meadow steppes and subalpine meadows, the density of hole entrances of which averaged 667 per hectare. Based on the density index of 0.16

10

Montane Steppe Ecosystem

individuals per entrance, the total number of this species averaged 106.7 individuals per hectare of pasture. Myospalax fontanieri is most abundant in alpine meadows, with a mound density from 70 to 218 per hectare. M. unguiculatus is a pest species throughout the region, with a density of active hole entrances reaching 600 to 1100 per hectare (Wei et al. 1999). Marmota baibacina ranges exclusively in the Xinjiang montane steppes. It is found widely in the montane typical steppe, forest steppe, and meadow steppe, occupying both sides of valley slopes with dense canopy cover, sufficient sunshine, and soft dry soils. The estimated total abundance of the species is roughly 350,000 individuals in Xinjiang, with a mean density of 1.2 individuals per km2 of pasture (Zhang et al. 2009b). Behaviorally, it goes into hibernation in mid-September and emerges in late March of the next year. It is a strictly diurnal animal, and forages generally within a radius of 30–50 m. It feeds almost completely on vegetation, with leaves and tender shoots of grasses most preferentially eaten. Its sex ratio is basically 1:1, with an even age structure. Important associates are Citellus undulates and C. erythrogenys (Zhao and Wang 1982). By contrast, one of its close relatives, M. caudata, is much less widespread and abundant, and is confined mainly to certain areas of the eastern Pamir Plateau. The estimated overall standing population of M. caudata is about 30,000 individuals, ranging in alpine, subalpine meadow steppes and montane steppes. It feeds mostly on the leaves and shoots of various plants, and on seeds and insects in small quantities in autumn (Zhang et al. 2009b). Myospalax fontanieri ranges most often on river valley terraces and gentle slopes with humid and loose-structured soils in the montane grassland, whereas it is seldom present in scrubs or alpine grasslands. It is more abundant and frequent in dry years while less so in moister years. Morphologically, it has a fat, thickly tube-shaped body and is rather nearsighted with small eyes. Behaviorally, the majority of its activity takes place below ground, and thus it has a considerable capacity for digging holes and creating mounds on the ground, resulting in severe damage to pastures. The density of mounds varies substantially from site to site, with a range of 1291–55,500 mounds per hm2 reported in a Tianzhu montane grassland (Yao and Wang 1964). The size of the soil dune varies from 33 to 230 cm in diameter. On average, the coverage of mounds approximates 452 m2 per hectare of pasture (Song et al. 1984). The species feeds mainly on the roots and rhizomes of plants, and the leaves and shoots of Carex and Potentilla anserina at times. Its daily intake averages 42 g of dry herbage per adult. This rodent has considerable effects on the succession of vegetation. For example, Elsholtzia calycocarpa is usually the first species to occupy freshly laid mounds, accompanied by several annual forbs such as Capsella bursa-pastoris, Artemisia annua, and Taraxacum spp. With grazing and wind or rain

10.7

Fauna

erosion, mounds gradually become lower and more compact after a few years, which favors the presence of perennial plants such as Kobresia and Carex spp., with Potentilla spp., Artemisia vulgaris, and Aster altaicus as common associates. After a period of 5–6 years, Potentilla anserina becomes dominant, with Kobresia and Carex spp. as the co-dominant species, marking that the restoration has reached its original state (Yao and Wang 1964). The hole system, usually including 66 hole entrances, is double-decked, the top deck of which is multibranched, 10–12 cm below the ground, 200 m or so in length, and 8–12 cm in diameter, and used mainly for foraging passage. The lower deck is usually about 2.5 m under the ground, includes five branches, and is used mainly for bedding, food storage, and excretion (Song et al. 1984). The tunnel system is rather complicated, consisting of a major den, upright hole, blind hole, passage tunnel, blocked tunnel, storage cell, and lavatory cell (Fan and Gu 1981). Mustela altaica and M. eversmanni prey on Myospalax fontanieri in some areas.

10.7.5 Insecta The Tianshan Mountains have probably the most numerous Acridoidean species in China. In total, 150-odd species have been observed in the various montane grasslands and woodlands here, distributed in 59 genera and 8 families. Of these, 98 species occur exclusively on the southern side of the mountain range, and 16 occur exclusively on the northern side, with 37 species shared by both sides (Li 2012). Tetrix subulata, Chorthippus albomarginatus, Pararcyptera microptera microptera, Omocestus haemorrhoidalis, O. viridulus, Myrmeleotettix palpalis, Gomphocerus s. sibiricus, and Bryodema gebleri mongolicum are the common species on the southern piedmonts at altitudes from 2460 to 3070 m (Li et al. 2008). For most of the grasshopper species, only one generation occurs in a year, with a lifecycle characterized by the hatching of overwintering eggs from late April until mid-August, the presence of nymphs from early May to early August, and the occurrence of adults from mid-May to late September. Oviposition of the current-year female adults starts in mid-June and lasts till mid-August. Eggs overwinter in the soil. Gomphocerus sibiricus usually feeds on grasses, sedges, Taraxacum mongolicum, and Allium spp.; Dociostaurus kraussi prefers to eat Salsola spp., Ceratoides latens, Artemisia hedinii, and grasses; Calliptamus italicus feeds on forbs such as Salsola spp., Artemisia spp., Lappula echinata, Echinopilon divaricatum, Galium aparine, Geranium pratense, and legumes; Oedaleus decorus selects grasses and forbs more preferentially; Bryodema gebleri feeds on grasses and certain species of Allium, Salsola, Artemisia, and Cephalanoplos (Baliqun 1977). In different types of the Qilian Mountains grasslands dominated by Stipa spp. and Artemisia spp., a total of

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28 grasshopper species (or subspecies) belonging to 15 genera and 7 families are currently recognized (Sun et al. 2010). The species richness ranges from 7 to 23 species per grassland type, being lowest in the alpine scrub and highest in the alpine grassland, while that of the desert grassland and the alpine meadow ranks in between. Oedipodidae and Arcypteridae have 10 and 9 species, respectively; Chorthippus brunneus, Ch. dubius, and Gomphocerus licenti are most common, while Myrmeleotettix palpalis is most abundant in the various grassland types, with Sphingonotus elegans and Bryodema qilianshanensis endemic to this region. In the Manas montane steppe of Xinjiang, 11 grasshopper species of 4 families have been identified, including Dociostaurus kraussi kraussi, Notostaurus albicornis, Omocestus haemorrhoidalis, Stauroderus scalaris scalaris, Oedaleus decorus decorus, Calliptamus italicus, C. coelesyriensis, Gomphocerus sibiricus, and Stenobothrus eurasius. The species composition and relative abundance of grasshoppers was found to differ substantially among different communities, with O. decorus decorus most dominant in the communities consisting of Carex spp. and Kobresia spp., D. kraussi kraussi most dominant in Salsola collina stands, and Chorthippus spp. most prominent in Festuca dominated subalpine swards (Wang 2013). Locusta migratoria migratoria is a major pest locust species infesting Xinjiang grasslands. However, it has begun infesting northeast China in recent years, with a density as high as 1000–2000 ind./m2 observed during outbreaks. Li et al. (2012) observed that only one generation of this locust occurs annually in northeast China, and its eggs are laid in the soil to overwinter. The post-overwintering eggs begin to hatch in early or middle June and reach their hatching peak in mid-June. The developmental duration of nymphs lasts 28–35 days, with each nymph stage lasting 5–7 days. The emergence time of adults occurs in early July. Roughly 1 week following emergence, the adult males and females begin to copulate and reach peak reproduction in late July. The adult begins to oviposit in early August after 2 weeks of copulation, and oviposition activity lasts until early October. In a Stipa montane steppe occurring on the piedmont of the Qilian Mountains, 13 species of grasshoppers were observed, with Gomphocerus licenti, Oedaleus decorus, and Chorthippus albonemus being most abundant and Ch. fallax and Euchorthippus spp. occasional. The species richness of grasshoppers was found to be significantly positively correlated with both canopy coverage and plant species richness, but negatively correlated with canopy height (Zhou et al. 2011). A comparative study in the Ningxia grasslands demonstrated that the montane meadow steppe generally had the least species richness and lowest abundance of grasshoppers and locusts out of all of the other kinds of grasslands in the same area (Table 10.20). Omocestus

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Montane Steppe Ecosystem

Table 10.20 Species composition and relative abundance of grasshoppers in different types of grasslands in Ningxia No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 Total

Species Filchnerella beicki Haplotropis brunneriana Filchnerella alashanicus Atractomorpha sinensis Angaracris rhodopa Epacromius coerulipes Epacromius barbarus Bryodemella holdereri Bryodemella tuberculatum Bryodemella nigroptera Compsorhipis davidiana Epacromius coerulipes larvae Oedaleus infernalis Oedaleus decorus Sphingonotus ningsianus Sphingonotus yanchiensis Chorthippus aethalinus Ch. albonemus larvae Ch. biguttulus Ch. brunneus Ch. hammarstroemi Ch. albonemus Ch. hsiai Ch. louguanensis Euchorthippus unicolor Omocestus petraeus Omocestus haemorrhoidalis Comphocerus licenti Pararcyptera microptera Myrmeleotettix palpalis Euthystira yuzhongensis Acrida cinerea Formosatettix helanshanensis Paratettix uvarovi Gampsocleis inflata Mongolodectes alashanicus Zichya tenggerensis Oxya chinensis Tetrix tartara

Grassland types Steppe desert 173 22 66 9 23 6 130 42

Desert steppe 236

Steppe 197

Meadow steppe 21

43

49

18 6 97 15

70 84

36

4

12

95 56 37 32 9 30 10 7 57

53 12

3

22 9

95 20

12 82

44 591 4 49 4 8 3 1

5 2 5 2

4 1 4 3

34

37 46 4 5 17 1

4 30 271 3

4 78 15

1 9

13

6 28

62

86 28 14 12

22

67 125

16 42 61

1 1154

758

1575

12 38 435

Total 627 22 158 9 147 96 227 57 16 148 71 37 149 72 30 10 100 776 4 62 12 34 9 1 4 34 349 18 86 28 1 58 12 6 173 167 61 13 38 3922

Prop. (%) 15.99 0.56 4.03 0.23 3.75 2.45 5.79 1.45 0.41 3.77 1.80 0.94 3.80 1.84 0.76 0.25 2.55 19.79 0.10 1.58 0.31 0.87 0.23 0.03 0.10 0.87 8.90 0.46 2.19 0.71 0.03 1.48 0.31 0.15 4.41 4.26 1.56 0.33 0.97 100.00

Note: the steppic desert is dominated by Reaumuria soongorica and Salsola passerina, the desert steppe is dominated by Stipa breviflora and Lespedeza davurica, the typical steppe is dominated by Stipa bungeana and Artemisia frigida, and the alpine meadow steppe is dominated by Stipa przewalskii, Artemisia gmelinii and A. subdigitata. (After Huang et al. 2014) Abbreviations: Prop proportion

haemorrhoidalis and Tetrix tartara were most abundant in this steppe, whereas they were totally absent in the two desert grasslands. Additionally, the similarity index of the grasshopper communities of this steppe compared with any of the desert grasslands was always lower than 60% (Huang et al. 2014). In the Xiahe montane grassland occurring on the northern section of the Qinling Mountains, Yang (2007) found that

Chorthippus dubius, Myrmeleotettix Palpalis, Chorthippus fallax, and Angaracris spp. were the most abundant grasshopper species, accounting for 61.8%, 16.7%, 7.4%, and 7.4% of the total abundance of all the grasshoppers, respectively. The species richness of grasshoppers varied substantially among different plant communities, ranging from 4 species in a Kobresia pasture to 17 in an Orinus kokonorica steppe (Table 10.21).

10.7

Fauna

331

Table 10.21 Species number and relative abundance of grasshoppers in different grassland communities of Qinling Mountains, Xiahe C 1 2 3 4 5 6 7 8 9 10

SN No. 13 8 8 13 14 17 15 15 16 4

Prop. 11.30 6.96 6.96 11.30 12.17 14.78 13.04 13.04 13.91 3.45

A Ind. 69 47 47 348 356 324 366 368 482 18

Prop. 2.72 1.85 1.85 13.73 14.05 12.79 14.44 14.52 19.02 7.10

Note: (1) Achnatherum splendens salt meadow; (2) Marsh; (3) Iris lactea + Blysmus sinocompressus salt meadow; (4) Kobresia capillifolia + Carex crebra + Stipa aliena steppic meadow; (5) Kobresia capillifolia + Carex crebra + Stipa purpurea steppic meadow; (6) Orinus kokonorica + Ajania tenuifolia + Aristida triseta montane steppe; (7) Brachypodium sylvaticum + Carex crebra subalpine meadow; (8) Elymus dahuricus + Medicago ruthenica subalpine meadow; (9) Kobresia capillifolia + Polygonum viviparum + Bromus sinensis subalpine meadow; (10) Kobresia pygmaea + K. humilis + K. capillifolia alpine meadow. Abbreviations: C plant community, SN species number of grasshoppers, A abundance of grasshoppers. (Modified from Yang 2007)

Tussock moths such as Gynaephora alpherakii, G. qinghaiensis, G. aureata, G. ruoergensis, and G. minor are the most principal species damaging various montane steppes and alpine meadows in Qinghai, southern Gansu, and northwestern Sichuan. In addition, soil-dwelling beetles are also harmful in these regions (Liu et al. 1993).

10.7.6 Soil Fauna In four montane steppes of Xinjiang, Li et al. (2000) identified 27 groups of soil animals distributed among 22 orders, 6 classes, and 4 phyla, among which Nematoda contained the most individuals. Commonly shared groups were Oligochaeta Plesiopora (notably Enchytraeidae), Acarina, Coleoptera, and Hymenoptera (Table 10.22). Fencing consistently led to significant increases in both the group richness and the overall abundance of soil animals in the steppes. Vertically, the 0–10 cm soil layer accounted for more than 60% of the total individuals and the most diverse groups. Soil moisture and organic matter contents were significantly positively related to the abundance of soil animals in this region.

Table 10.22 Categories and relative abundances of soil animals in different montane steppes of Xinjiang Group Nematoda Oligochaeta: Opishoplatia Oligochaeta: Plesiopora Mesogastropoda Stylommatophora Chilopoda Diplopoda Araneida Acarina Collembola Orthoptera Orthoptera nymphae Coleoptera Coleoptera larvae Diplura Diplura larvae Lepidoptera Lepodoptera larvae Hemiptera Hymenoptera Dermaptera Odonata GN/TIN

Subalp. mdw IN 288 4 33

AC +++ + ++

4 2 5 19 4 16 3 27 2 5 3 2 1

+ + ++ ++ + ++ + ++ + ++ + + +

13 9 1 19/441

++ ++ +

Mont. steppe IN 333 2 46 6 2 5 3 30 5 8 3 28 2 2 6 6 2 1 18 10 3 21/521

AC +++ + ++ ++ + + + ++ ++ ++ + ++ + + ++ ++ + + ++ ++ +

Alp. steppe IN 239

AC +++

59

+++

1 1 27 3

+ ++ + ++ +

1 18 4 3 1

+ ++ ++ + +

2 10

+ ++

13/369

Alp. mdw IN 240 2 25 10 2 1 1 2 25 1 3 2 15 2 9 3 1 1

+ + + + ++ + + + ++ + ++ + + +

10 4

++ ++

AC +++ + ++

20/359

Abbreviations: mdw meadow, Subalp. subalpine; IN individual number observed, AC abundance class; +++ dominant, the number of individuals accounts for more than 10% of the total; ++ common, 1–10%; + rare, less than 1%; GN group number; TIN total number of individuals. (Adapted from Li et al. 2006a, b, c, d, e)

332

10

Montane Steppe Ecosystem

Table 10.23 Composition and relative abundance of soil animal groups in different habitats of the Kanas Nature Reserve Group Oribatida Collembola Tylenchida Mesostigmata Astigmata Bdelloidea Prostigmata Dorylaimida Diptera larvae Coleoptera larvae Symphyla Lepodoptera larvae Araneida Acerentomata Hymenoptera Scolopendromorpha Thysanoptera Diplura Tetramerocerata Hemiptera Tubificida Opiliones Orthoptera Geophilomorpha Psocoptera Isoptera Isopoda Pseudoscorpiones Lithobiomorpha Dermaptera Total individuals Total group

Conif. 933 289 313 64 174 121 39 52 39 19 19 19 18 17 11 11 8 7 6 2 0 1 0 0 0 0 0 0 0 0 2162 21

Mixed 2232 446 381 303 250 146 59 75 51 24 12 17 19 3 7 1 4 5 3 0 15 2 2 0 0 0 1 0 2 0 4060 24

Broad 1617 547 253 132 232 162 78 45 9 17 3 6 7 10 3 1 3 15 4 6 49 0 0 2 2 2 2 2 0 1 3210 27

Scrub 1102 229 196 112 78 14 32 25 12 16 3 9 6 11 22 0 0 5 1 1 8 1 1 0 3 2 1 2 1 0 1894 25

Pasture 848 176 151 177 27 19 29 25 19 11 4 6 7 9 2 1 3 7 3 0 13 0 2 4 0 0 5 0 0 0 1548 23

Steppe 314 71 102 13 19 19 3 23 3 5 4 2 3 3 1 1 0 2 1 0 3 1 0 0 0 0 0 0 0 0 923 20

Mdw 205 98 136 45 41 86 75 75 21 5 2 7 5 1 1 3 0 0 0 0 25 0 0 0 2 0 0 0 0 0 504 18

Total 7251 1856 1532 846 821 567 315 320 154 97 47 67 65 54 47 18 18 41 18 9 113 5 5 6 7 4 9 4 3 1 14,301 30

Prop. 50.71 12.98 10.71 5.92 5.74 3.96 2.20 2.24 1.08 0.68 0.33 0.47 0.45 0.38 0.33 0.13 0.13 0.29 0.13 0.06 0.79 0.03 0.03 0.04 0.05 0.03 0.06 0.03 0.02 0.01 100.00

Abund. +++ +++ +++ ++ ++ ++ ++ ++ ++ + + + + + + + + + + + + + + + + + + + + + +

Note: Coniferous forest dominated by Larix sibirica and Picea obovata; coniferous and broad-leaved mixed forest dominated by Larix sibirica, Picea obovata, Populus tremula, and Betula pendula; broad-leaved forest dominated by Populus tremula and Betula pendula; scrub dominated by Lonicera caerulea, Rosa spinosissima and Spiraea chamaedryfolia; inter-forest pasture dominated by Poa pratensis, Carex polyphylla and Iris ruthenica; meadow steppe dominated by Roegneria mutabilis, Fragaria viridis and Koeleria cristata; marshy meadow dominated by Carex riparia, C. caespititia and Poa sibirica. +++ dominant, with individuals accounting for more than 10% of the total; ++ common, 1–10%; + rare, less than 1%. (Abliz et al. 2014)

Abliz et al. (2014) reported 29 orders of soil meso- and microfauna, distributed among 13 classes within 4 phyla, in the various Kanas montane ecosystems of Xinjiang. Oribatida, Collembola, and Tylenchida were the dominant groups, which together accounted for 74.44% of the total abundance of the soil animals observed in all of the habitats as a whole. Mesostigmata, Astigmata, Bdelloidea, Prostigmata, Dorylaimida, and Dipteran larvae were the common groups, making up 21.14% of the total collections; the remaining 23 groups were rare. There were considerable differences among the different habitats in terms of both total abundance and group richness (Table 10.23). The maximum individual density and group number all occurred in the 0–5 cm soil layer. Peak values of total abundance appeared in

September for most of the communities of soil animals associated with the relevant kinds of vegetation. In a montane meadow steppe of northern Hebei, 18 orders of soil arthropods were recognized, among which Acarina, Collembola, and Hymenoptera were the most abundant groups, while Araneae, Homoptera, Lepidoptera, Coleoptera (imag.), Coleoptera larvae, and Diptera larvae were the common ones (Zhu et al. 2007). By contrast, in a montane meadow steppe dominated by Sanguisorba officinalis and Artemisia tanacetifolia occurring in the same area, Liu et al. (2016a, b, c) revealed 46 species of soil mites that were distributed among 4 orders (Table 10.24). Dominant species were Hypoaspis queerlandicus, Microppia minus, and Microppia spp., each, respectively, accounting for 17.8%,

10.8

Microbes

333

Table 10.24 Species composition and abundance (ind./m2) of soil mites and ticks as affected by livestock grazing in a montane meadow steppe of northern Hebei Taxa Acari 1. Astigmata Acarus siro Aleuroglyphus ovatus Histiostoma sp. Pandalura sp. Tortonia sp. Tyrophagus putrescentiae Tyrophagus sp. 2. Prostigmata Alicorhagiidae sp. Cheyletus malaccensis Cheyletidae sp. Eustigmaeus sp. Mahunlania sp. Scutacaridae sp. 3. Mesostigmata Asca sp. Cheiroseius nepalensis Cheiroseius sp. Dendrolaelaps sp. Gamasellus sp. Unidentified sp. Hypoaspis queerlandicus

Inside 4840 220 60 20 80 20 – 20

SE 940 102 24 20 80 20 – 20

Outside 4325 300 100 175 – – 25 –

SE 1051 191 100 103 – – 25 –

Prop. 100 5.54 + 1.69 + 1.93 0.96 0.24 0.24 0.24

20 340 120 20 20 120 40 20 1560 20 20 20 180 180 – 1060

20 68 37 20 20 97 40 20 501 20 20 20 66 92 – 401

– 200 100 – – 100 – – 975 – – – 375 – 75 525

– 135 100 – – 41 – – 239 – – – 165 – 75 202

0.24 6.02 + 2.41 0.24 0.24 + 2.41 0.48 0.24 28.2 0.24 0.24 0.24 + 5.78 2.17 0.72

Neparholaspis sp. 4. Oribatida Macropylina group Allonothrus sp. Archegozetes sp. Epilohmannoides sp. 1 Epilohmannoides sp. 2 Haplochthonius sp. Heterochthonius gibbus Nothrus sp. Nothrus biciliatus Platynothrus sp. Pseudocryptacarus sp. Rhysotritia ardua Trhypochthonius sp. Unidentified sp. Gymnonota group Hypogeoppia sp. Microppia minus

80 2720 400 40 20 140 20 20 20 20 60 20 20 – – 20 1940 40 1240

80 1033 32 24 20 75 20 0 20 20 40 20 20 – – 20 1007 40 816

– 2850 500 – – 50 325 – – – – 75 – 25 25 – 1050 – –

– 665 265 – – 29 236 – – – – 25 – 25 25 – 377 – –

725

317

280

97

17.8 0.96 60.2 9.64 0.48 0.24 + 2.17 + 3.37 0.24 0.24 0.24 0.72 0.96 0.24 0.24 0.24 0.24 33.5 0.48 + +

60 300 – 20

60 138 – 20

75 125 25 100

48 48 25 41

14.9

+ +

Oppielia nova Oppia sp. Suctobelbella sp. Tectocepheus velatus

Taxa Poronata group Anachipteria sp. Heminothrus sp. Scheloribates latipes Trichogalumna nipponica Xylobates sp.

Inside 380 100 20 20 100

SE 124 77 20 20 63

Outside 1300 525 – – 125

SE 258 85 – – 95

Prop. 17.1 + 6.27 0.24 0.24 + 2.41

140

93

312

312

+

7.95

Note: ++ dominant, + common; sample number is 25 inside the enclosure and 24 outside the enclosure; SE standard error. (After Liu et al. 2016b)

14.9%, and 10.4% of the total abundance. Vertically, superficial aggregation was most conspicuous for orders Prostigmata and Mesostigmata, while individuals of Oribatida and Astigmata were either evenly distributed along the profile or subsoil-tending. The total species number of soil mites inside the enclosure (41 species) far exceeded that outside (21 species), and the abundance and vertical distribution pattern within the soil were also altered considerably for some species by fencing, meaning that grazing had substantial species-specific effects on the community of soil mites.

10.8

Microbes

+ +

Microppia sp.

Table 10.24 (continued)

10.4 1.45 + 4.82 0.24 + 1.21 (continued) +

Cao et al. (2008) showed that actinomycetes were relatively abundant in a variety of montane meadow steppes in Bayanbulak, Xinjiang, constituting 25–50% of the total abundance of the soil microflora. In the montane steppe occurring on the Qilian Mountains, estimates of the density of culturable nitrogen-fixing bacteria in topsoils were between 2 and 3  105 CFUs per gram of dry soil in a Stipa przewalskyi community (Kang et al. 2013), 16.57  105 CFUs in a shortgrass community, and 55.56  105 CFUs in a Polygonum viviparum community (Han et al. 2007). In addition, ammonifiers, nitrate bacteria, and denitrifying bacteria in the topsoil were particularly abundant in some communities, while nitrite bacteria were exceptionally rare (Han et al. 2007). Estimates of the abundance and the biomass content of soil microbes in topsoils of different montane steppe communities are summarized in Tables 10.25 and 10.26. Pu et al. (2013) found that short-term grazing significantly enhanced the content of microbial biomass in the 0–30 cm soil layer in an Ili montane meadow steppe, with that under moderate grazing being maximal. Liu (2010) investigated five montane typical communities along an altitudinal gradient on the eastern section of the Helan Mountains and found that the montane desert steppe composed of Stipa breviflora and Cleistogenes songorica had the lowest standing crop of

334

10

Montane Steppe Ecosystem

Table 10.25 Abundances of microorganisms in topsoils of different montane steppe communities Community Polygonum viviparuma Short grassa Kobresia spp.a Festuca ovinab Suaeda glaucab Salsola collinab

Location Qilian Mts. Qilian Mts. Qilian Mts. Shihezi Shihezi Shihezi

Bacteria (106/g ds) 11.8856 14.0244 8.8600 70 65 27

Actinom. (105/g ds) 65.254 124.527 69.108 55.0 75.5 32.5

Fungi (104/g ds) 2.70 5.60 4.08 3.85 1.25 0.15

Total (106/g ds) 18.4380 26.5331 15.8205 75.5385 72.5625 30.2515

Reference Han et al. (2007) Han et al. (2007) Han et al. (2007) Guo et al. (2011) Guo et al. (2011) Guo et al. (2011)

Note: aMontane meadow steppe; bMontane desert steppe

Table 10.26 Estimates of soil microbial biomass contents (mostly at the 0–20 cm soil layer) in different montane steppes Community Thymus asiaticus Stipa purpurea Kobresia capillifolia Stipa breviflora Meadow steppe Festuca ovina Suaeda glauca Salsola collina

Location Ili Tianshan Tianshan Helan Qilian Shihezi Shihezi Shihezi

MBC (mg/kg) 447.025 43.06 181.70 40 648.96 1051.39 698.12 262.08

MBN (mg/kg)

10 58.40 65.95 38.73 4.41

SOC (g/kg) 51.93 83.54 98.73 6.28 25.54 10.21 13.56 6.31

MBC/SOC 0.86 0.05 0.18 0.64 2.54 10.30 5.15 4.15

References Pu et al. (2013) Li et al. (2012) Li et al. (2012) Liu (2010) Wu and Ai (2008) Guo et al. (2011) Guo et al. (2011) Guo et al. (2011)

Abbreviations: MBC microbial biomass carbon, MBN microbial biomass nitrogen, SOC soil organic carbon

soil microbial biomass (120.8 kg C hm2 to the 20 cm soil depth), while that of the montane meadow dominated by Kobresia helanshanica and K. humilis was highest (694.4 kg C hm2).

10.9

Succession and Management

In a Festuca ovina pasture of the Bayanbulak montane grassland, Gong et al. (2010) observed that the grazing-resultant retrogressive succession was characterized by a sequence of four stages: the climax community dominated by Festuca ovina, Stipa purpurea, and Agropyron cristatum; the lightly degraded stand composed of Festuca ovina, Potentilla spp., and A. cristatum; the moderately degraded stand consisting of Festuca ovina, Oxytropis spp., and Koeleria cristata; and the heavily degraded stand dominated by Leymus tianschanicus, Oxytropis spp., and Potentilla spp. The species richness was highest at the moderate degenerative stage, while the maximum root biomass was measured at the heavy degenerative stage (Tables 10.27 and 10.28). By contrast, livestock exclusion resulted in a progressive succession from the Leymus tianschanicus + Oxytropis ochrantha community to the Festuca ovina + Stipa purpurea community (Hu et al. 2009). They found that fencing significantly reduced the dominance values of Leymus tianschanicus, Potentilla multifida, and Oxytropis ochrantha, while it substantially increased the proportion of bunchgrasses, including Agropyron cristatum and Koeleria cristata. However, the species richness and diversity were

lowered considerably, while species evenness increased to a certain extent with the duration of livestock exclusion. The standing crop of canopy biomass did not change much during the 5 years of fencing, whereas the proportion of grasses showed an increasing trend. In stark contrast, the root biomass increased by nearly twofold, being 487.16, 480.53, 529.29, and 1112.16 g per 0.25 m2, respectively, for the grazed, 1-, 3-, and 5-year fenced stands. Selective feeding on different plant species with varying palatability is assumed to be an important element influencing the species composition of the relevant stands at different successional stages. In a montane meadow steppe occurring on the Zhaosu ranch in the northern Tianshan Mountains, the climax Carex liparocarpos community usually consists of Festuca ovina, Thymus asiaticus, and Poa pratensis, accompanied by Stipa capillata, Medicago falcata, Astragalus spp., Achillea millefolium, and Bromus inermis. Li et al. (2009) observed that C. liparocarpos was less impacted by spring-autumn grazing, while grasses and legumes were significantly depressed, with Thymus asiaticus an increaser. Li and Wang (1992) found that the species composition and dominant species did not change significantly under different grazing intensities in a Poa pratensis meadow steppe occurring on the eastern section of the Qilian Mountains. However, the standing crop of total biomass fell by as much as three quarters, and the ratio of palatable to unpalatable plant biomass decreased from 1.28 to 0.67. Melica przewalskyi is a perennial grass that occurs vastly in the degraded montane steppes of Gansu, Qinghai, and Tibet. It is unpalatable because of its awful odor. To control

References

335

Table 10.27 Variations in canopy biomass of a F. ovina community at different stages of degradation (g/0.25 m2) Stage Climax Light Moderate Heavy

Grass 32.88  1.90a 8.83  0.80c 13.27  1.49bc 15.02  1.62b

Legume 0 2.02  1.05b 6.03  1.58a 3.62  0.65b

Forb 2.50  0.73b 4.59  1.27a 5.01  1.17a 5.83  1.48a

Total 35.37  2.52a 15.44  0.28c 24.31  2.14b 24.46  2.70b

Values with different lower-case letters in a column denote a significant difference at p < 0.05. (After Gong et al. 2010) Table 10.28 Variations in root biomass of a F. ovina community at the different stages of degradation (g/0.05 m3) Stage Climax Light Moderate Heavy

0~10 cm 7.65  2.55ab 8.29  1.52ab 5.42  0.41b 9.48  0.34a

10~2 cm 2.04  0.29ab 1.43  0.08b 1.20  0.13b 2.52  0.68a

20~30 cm 1.47  0.18a 0.92  0.13a 1.15  0.09a 1.54  0.14a

Total 11.15  2.85ab 10.64  1.71ab 7.77  0.43b 13.54  0.48a

Values with different lower-case letters in a column denote a significant difference at p < 0.05. (After Gong et al. 2010)

Table 10.29 Dynamics in coverage and biomass of a Melica przewalskyi community in response to herbicide application Item Coverage (%) Density(ind./m2) Biomass (g/m2)

2000 80  4.7 188  6 81  3.8

2001 3  0.1 11  0.4 2.1  0.1

2002 11  0.4 28  1.1 4.9  0.2

2003 20  0.9 72  29 7.9  0.3

2004 32  1.3 99  3.6 20.1  0.8

2005 53  2.2 149  7.4 33.6  1.3

2006 66  2.8 218  10.9 37.8  1.5

CK1 72  2.9 196  9.4 82.9  3.3

CK2 65  2.8 418  19.2 48.9  1.9

Table 10.30 Dynamics of root biomass in a Melica przewalskyi community in response to herbicide application (dry weight g/m3) Depth (cm) 0~10 10~20 20~30 30~40 40~50 Total

Treated plot Live 623  24.9 52  2.3 73  3.2 28  1.3 20  0.9 796  32.6

Dead 1696  81.4 415  18.7 428  18.8 107  5 55  2.8 2700  126.7

Total 2319  106.3 467  21 501  22 135  6.3 74  3.6 3496  159.3

this species, a common practice is to apply herbicide on the canopy. Zhao and Long (2008) found that after herbicide treatment, grassland restoration was characterized by the following progressive sequence: the Melica przewalskyi stand, the Artemisia frigida + M. przewalskyi stand, the A. frigida + Stipa krylovii stand, and the S. krylovii + forb stand. Compared with the control, the species number increased from 4 to 7 after 6 years of treatment, but no significant differences in cover and density occurred (Table 10.29). The amount of root biomass also did not change significantly (Table 10.30). However, the roots were apparently more concentrated downward to deeper soil layers.

References Ablimit A, Noriyuki O, Mahmut H, Hayashida E (1999) Characteristics of mammalian fauna and it’s distribution in the Kanas Nature Reserve. Arid Land Res 16(2):25–30

Untreated plot Live 652  27.4 56  2.5 48  2.3 11  0.4 3  0.2 769  32.7

Dead 1670  80.2 753  34.6 429  19.3 137  6.7 88  4.2 3076  145

Total 2321  107.5 809  37.1 476  21.6 147  7.2 91  4.4 3845  177.7

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10

Montane Steppe Ecosystem

Li GY, Reyimu T, Zheng W, Li H et al (2009) Study on degenerating succession and species diversity of a spring-autumn grazing pasture in Zhaosu Horse Farm of Xinjiang. Xinjiang Agric Sci 46 (6):1368–1372 Li WL (2012) Studies on Acridoids in the Tianshan Mountains of Xinjiang. Herbavorous Livestock 2:27–30 Li M, Chen WJ, Wei W, Wang C et al (2012) Diversity of breeding birds in middle Inner Mongolia. Chin J Zool 47(3):102–108 Liu NF, Wang ND (1987) Survey on the community structure of summer birds on the Lenglong ridge of Gansu. J Lanzhou Univ 23 (3):77–91 Liu AP, Song YF, Xü ST, Bai WH (1993) Investigation of the kinds of pest insects in major regions of northern grasslands. Grassl China 4:60–63 Liu BR (2010) Changes in soil microbial biomass carbon and nitrogen under typical plant communities along an altitudinal gradient in east side of Helan Mountains. Ecol Environ Sci 19(4):883–888 Liu J, Zhao Y, Zhang QM, Xü SJ et al (2016a) Effects of land use on soil microbial biomass and community structure in the loess hilly region of western Henan. Acta Pratacul Sin 25(8):36–47 Liu MP, Qin WH, Li ZL, Wang YJ et al (2016b) Soil mite community structure in response to short-term grazing exclosure and characteristics as indicators of environmental quality in Hongsongwa Natural Reserve. Ecol Environ Sci 25(5):768–774 Liu WT, Wei ZJ, Lü SJ, Sun SX, Dai JZ (2016c) Estimation of biomass allocation and carbon density in different land-use types in Stipa breviflora desert grassland. J Desert Res 36(3):666–673 Ma Y (1981) On geographic distribution of rodents in northern Xinjiang. Acta Zool Sin 27(2):180–187 Ma JY, Sun W, Zhang HW, Xia DS (2009) Stable Carbon isotope characteristics of different Plant species and surface soil in arid regions. Front Earth Sci China 3(1):107–111 Peng J, Li GY, Yan K (2011) Phytomass of a degraded grassland in Zhaosu, Xinjiang. Herbiv Domest Anim 3:68–70 Pu NN, Sun ZJ, Fan YM, Yang HL (2013) Influence of grazing intensity on the soil organic carbon and microbial biomass carbon of meadow steppe in Zhaosu Area. J Xinjiang Agric Univ 36(1):66–70 Qu D, Gong DJ, Qin J, Chen Z et al (2016) Community structure and diversity analysis of the summer birds in Tianzhu. J Arid Land Resour Environ 30(5):162–167 Ren JZ (2008) Prataculture encyclopedia. China Agriculture Press, Beijing Rodwell JS, Pigott CD, Ratcliffe DA, Malloch AJC et al (eds) (1992) British plant communities, vol 3. Grasslands and Montane Communities. Cambridge University Press, Cambridge Song ZM, Luo WY, Wang DQ (1984) Investigation on the damage of Myospalax fontanieri to Tianzhu grassland. Chin J Zool 3:27–30 Song ZM, Luo WY, Wang DQ (1985) Vertical distribution pattern of Aves in Tianzhu area. J Lanzhou Univ (biological issue):123–134 Song ZR (1996) Temperate deserts. In: Liao, Jia (eds) Rangeland resources of China. China Science & Technology Press, Beijing, pp 2233–2247 Sun ZJ, An SZ, Duan JJ (2009) Effects of enclosure on vegetation and soil nutrients of sage brush desert grassland in Xinjiang. Arid Land Res 26(6):877–882 Sun T, Long RJ, Liu ZY (2010) A comparative study of grasshopper species (Orthoptera: Acridoidea) diversity in different grasslands on the northern slope of Qilian Mountains. Acta Entomol Sin 53 (6):702–707 Sun X, Ding W, Jia HT, Du JL, Jin JX (2015a) Effects of mowing on montane steppes on the north slope of the Tianshan Mountains. Bull Soil Water Conserv 35(5):195–204 Sun ZJ, Zhang XH, Zheng W, Jin GL et al (2015b) Influence of shortterm grazing exclusion on underground biomass and distribution of meadow steppe in Zhaosu. Xinjiang Agric Sci 52(6):1119–1125 Wang YF (1963) Basic characteristics of montane steppe on the eastern Tianshan Mountains. Acta Phys Sin 1(1):110–130

References Wang GM, Zhou QQ, Zhong WQ, Wang GH (1992) Food habits of Microtus brandti. Acta Theriol Sin 12(1):57–64 Wang SG, Zeng ZY, Wu PF, Lan ZJ et al (2004) The home range of Phrynocephalus vlangalii. J Sichuan Univ 41(2):403–408 Wang X, Hu YK et al (2008) Study on gradient changes of soil factors and underground biomass of alpine grasslands on the southern slope of the Tianshan Mountains. Chin J Grassl 30(6):67–73 Wang LJ, Liu ZS, Zhai H, Han J et al (2010) Species diversity and faunal characteristics of amphibians and reptiles in Helan Mountains. Chin J Ecol 29(11):2293–2297 Wang JH (2013) Grasshopper species composition and diversity in different communities of Manas montane steppe. J Xinjiang Anim Hus 10:60–62 Wang DW, Sheng JD, Liu YH, Zha XH, Men XH (2014a) Analysis of grassland biomass and the impact factors on the north slope of the Tianshan Mountains. Pratacult Sci 31(1):125–131 Wang SL, Jin M, Zhang XL, Li XY (2014b) Comparative study on natural mountain grassland biomass under conditions of different enclosure schemes. J Central-South Univ Forestry Technol 34 (12):130–135 Wei J, Zhang HP, Hu JL (1999) Study on species composition and community structure of grassland rodents in Zhangye Region. Pratacult Sci 16(6):26–31 Wu JG, Ai L (2008) Soil microbial activity and biomass C and N contents in three typical ecosystems of the Qilian Mountains. J Plant Ecol 32(2):465–476 Xiang LG, Huang RX (1986) Study on birds in Altay of Xinjiang. J Xinjiang Univ 3(3):90–106 Xü P, Ali MJ, Luo L, Song ZR, Wang B (1993) Grassland Resources and Their Utilization in Xinjiang. Xijing Science and Sanitation Press, Urumqi Yan WB, Zhang HH, Yang HJ, Dou HS et al (2006) Seasonal diet compositions of wolves in the Dalaihu Natural Reserve, Inner Mongolia. Chin J Zool 41(5):46–51 Yang YB (2007) Investigation of the grasshopper fauna in Xiahe grasslands. Grassl Animal Husbandry 8:30–32 Yang CD, Long RJ, Chen XR, Man YR et al (2007) Study on microbial biomass and its correlation with soil physical properties of the alpine

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Shrubby Steppe Ecosystem

Abstract

This chapter focuses on Chinese shrubby steppe ecosystems. It introduces in brief the areal extent and provincially based distribution of this ecosystem type; simply discusses the relevant physical features and climatic characteristics at a regional scale; elaborates in great detail upon the flora, fauna, and microflora composing the various shrubby steppe ecosystems; and describes in much greater detail the major formations or formation groups of the shrubby steppe vegetation nationwide. It also summarizes the standing crops of canopy and root biomass and their allocation pattern of certain important communities. In addition, it expounds on the succession characteristics and their responses to the management and utilization steps of certain shrubby steppe ecosystems. Keywords

Vegetal formation · Flora · Fauna · Microorganisms · Root-to-canopy ratio · Succession · Ecological sequence

It has long been debated whether the shrubby steppe, also termed the forest steppe, should be recognized as a separate steppe subtype hierarchically parallel to those elaborated previously. For instance, the Stipa bungeana formation has been placed under the typical steppe, while formations dominated by Thymus mongolicus and Artemisia gmelinii are usually assigned to the desert steppe. Zhu (1993) characterized the shrubby steppe as being dominated by caespitose grasses and fragmented in its distribution. He and other grassland ecologists thus contended that the shrubby steppe is a specific zonal steppe subtype dominated by perennial xerophilous grasses and composed of broadleaved mesophytic herbaceous dicots, with subordinate, secondary thermophilous shrubs sometimes occurring in the community (Hou 1960; Zhu 1983b; Wang 1985). We would not get very far in trying to justify the state of the # Springer Nature Singapore Pte Ltd. 2020 L. Li et al., Grassland Ecosystems of China, Ecosystems of China 2, https://doi.org/10.1007/978-981-15-3421-8_11

11

shrubby steppe from the vegetation perspective. Instead, what is certain is that, in terms of ecosystem attributes such as structure and function, especially when it comes to the characteristics of flora, fauna, and other biotic elements, the shrubby steppe indeed underpins an ecosystem type rather distinct from that dominated by the other steppes. Owing to gradual decreases in water and heat from the southeast to northwest in past centuries (very likely millennia), native vegetation, specifically the deciduous broad-leaved forest dominated by Quercus liaotungensis and other trees, was progressively replaced by steppes, creating the shrubby steppe that has become progressively perpetuated in the long, narrow, transitional belt (Zhu 1994). Its southern boundary starts at Lingqiu County, Shaanxi, in the east, stretching westward through Guancen and Lüliang areas of Shanxi, then southwestward striding over the Yellow River throughout Qingjian, Ansai, and Zhidan counties, Shaanxi, entering Gansu at Qingyang through southern Zhenyuan, and finally ending at Zhangxian County, Gansu. Its northern demarcation line basically runs in parallel to the southern one, starting at Hunyuan westward to Datong of Shanxi, turning a bit northwestward via Qingshuihe and the Junggar Banner of Inner Mongolia, then going all the way southwest through Shenmu, Yulin, Jingbian, and Dingbian counties of Shaanxi, further through Guyuan and Xiji of Ningxia, and ending at Jingyuan County of Gansu. The northeast-southwest boundary length is about 940 km directly, while the width varies from 30 to 120 km (Zhu 1994). The shrubby meadow steppe, the most dominant vegetal kind, consists primarily of mesoxerophilous and xeromesophilous herbs that are usually interspersed with isolated dwarf trees and xerophilous shrubs in the stand. On the other hand, certain communities of the typical steppe also enter the scope along mountain ridges in small areas from the north. These two kinds of steppe communities form the main body of the shrubby steppe, whereas communities of the desert steppe should not be included in the shrub steppe in the strict sense, although they are treated so at times. 339

340

11

Table 11.1 Regional distribution of the shrubby steppe in China 2

Province Shanxi Shaanxi Gansu Ningxia Total

Area (hm ) Meadow 19,377 94,206 65,441 179,024

Typical 438,313 535,420 3,088,432 779,177 4,841,342

Subtotal 438,313 554,797 3,182,638 844,618 5,020,366

Prop. (%) 8.7 11.1 63.4 16.8 100

As discussed in greater detail in the ensuing sections of this chapter, broad-leaved herbs are more abundantly found in the shrubby steppe than in any of its counterpart steppes. Woody plants commonly occurring in the community are basically dwarf tree species such as Prunus armeniaca var. ansu, Populus davidiana, Ulmus spp., Juniperus rigida, Pyrus betulifolia, Platycladus orientalis, and Pinus tabulaeformis (Zhu 1994). The relative coverage of the woody plants generally ranges from 5 to 10%, or occasionally less than 5%, of which shrubs and trees generally comprise half and half. Thus, they basically play an insignificant role in the community. The regional distribution of the shrubby steppe in China is given in Table 11.1.

Temperature and precipitation generally follow the same rhythm during the growth season. Precipitation decreases with increasing latitude, the mean annual amount of which ranges from about 150 mm in the northwest to approximately 800 mm in the southeast. Most of the precipitation (nearly two-thirds) falls during the summer, with a year-to-year variation rate of 20–30% on average and 3–10 times in extreme years. However, the evaporation rate increases significantly from southeast (1400 mm) to northwest (2000 mm). Annual sunshine hours total 2000–3000. Microclimates differ substantially on the Taihang, Helan, and Liupan Mountains, and at different positions of gullies and ravines on the Loess Plateau. The shrub steppe is effectively confined to the central-tosouthern transitional part of the Loess Plateau, where the mean annual temperature ranges from 7.5 to 8.5
C, whereas the mean annual precipitation is between 400 and 500 mm (Table 11.2). Where precipitation exceeds 550 mm, forests would become dominant; by contrast, at areas with precipitation below 400 mm, the typical steppe is often and the desert steppe is at times more prominent.

11.2 11.1

Shrubby Steppe Ecosystem

Soils

Climate

The climate of the shrubby steppe region is mostly warm temperate. It is generally cold and dry during winter and warm, and subhumid to semiarid in summer. The mean annual temperature ranges from 9 to 12
C in the south, covering the Weihe River valleys in Shaanxi and the Fenhe River drainage area in Shanxi, with a rather small extent; in the central portion, it falls to about 8
C on average, while it varies between 6 and 8
C in the north and northwest. Maximum monthly temperatures vary between 22 and 26
C from north to south, and the minimum are correspondingly between 14 and 2
C. The mean annual cumulative temperature varies considerably from south to north, with a range of 2500–4500
C (10
C), accompanied by a frostfree season of 150–250 days. The diurnal temperature difference is from 10 to 16
C on year-round average, with maximums of 28–30
C occurring in summer, which substantially favor the accumulation of dry matter for plants.

The dominant soils in the shrubby steppe region are the dark loessial soil, the loessal soil (also known as the yellow cultivated loessial soil or the yellow Mian soil), the montane meadow soil, and the loamy sierozem. The latter two have been elaborated in other chapters of this volume, and thus are not discussed here. The dark loessial soil is formed under the complex influence of steppe vegetation, loessal parent materials, and semiarid climate that are characteristic of the Loess Plateau. It is distributed mainly in northern Shaanxi, eastern Gansu, and southern Ningxia, with a total area of some 2.55 million hm2. About two-thirds of this soil has been cultivated for row crop growth up to present, and thus wind and water erosions occur ubiquitously. This soil, with parent materials of eolian loess, is characterized by a deep soil body (mostly 10–20 m deep), loose structure, and heterogeneous texture (Table 11.3). Silts are most prominent, accounting for more than 60% of the total mineral particles. It is rich in CaCO3, with an average

Table 11.2 Climatic parameters of the middle and eastern Loess Plateau shrubby steppe regions Region Northa Centralb Southc

Temperature (
C) MAT Jan. 5–8 15 to 11 8–9 10 to 8 6–8 8 to 7

July 20–23 22–24 19–23

CT 2700–3000 2500–3200 2000–3000

Prec. (mm) MAP 350–450 350–500 330–500

Jun.–Aug. 50–90% 60% 50–70%

A 1.5–3.0 1.8–2.5 1.3–1.8

FFD (day) 120–140 140–160 160–180

SH (h) 3000–3400 2600–3000 2400–2700

WD (10
C) 195–215 185–195 175–185

Note: aIncluding northern Hebei and Shanxi; bNorthern Shaanxi and eastern Gansu; cMiddle Gansu and southern Ningxia. Abbreviations: MAT mean annual temperature, CT cumulative temperature (10
C), MAP mean annual precipitation, A aridity, FFD frost-free days, SH sunshine hours, WD winter days. (After Li et al. 1980b)

11.2

Soils

341

Table 11.3 Porosity and texture characteristics of the dark loessial soil sampled from Mt. Yunwu shrubby steppe, Ningxia Soil depth (cm) 01–16 16–37 37–70 70–115 115–150

Density (g/cm3) 0.92 0.99 1.03 1.06 1.06

Porosity (%) NCP CP 11.7 54.0 7.8 55.3 5.1 56.5 2.3 58.1 6.3 54.3

T 65.7 53.1 61.6 60.4 60.6

Particle composition (mm, g/kg) >0.05 0.05–0.01 0.01–0.005 77.0 613.0 92.0 70.0 617.0 90.0 57.0 565.0 106.0 71.0 509.0 106.0 71.0 535.0 95.0

0.05 0.05–0.01 0.01–0.005 47.8 34.6 2.0 42.5 41.1 1.2 50.5 35.0 1.1 58.0 27.9 0.6 7.9 53.6 8.7 7.7 52.4 8.2 8.1 53.9 8.8 7.9 56.8 7.8 7.6 60.2 8.0 6.8 60.8 8.2 6.0 60.6 8.4 6.3 59.2 8.4 7.4 60.2 7.7 6.5 58.7 9.0

0.005–0.001 1.5 2.2 2.3 1.5 10.8 11.0 9.4 10.5 8.6 10.5 10.5 10.4 10.4 10.1

0.05 0.05–0.01 0.01–0.005 93 575 96 78 566 113 61 483 124 86 500 104 104 506 99 122 539 93

Abbreviations: SD soil depth, CP capillary pore, NCP non-capillary pore, T total porosity. (After Peng and Jia 1997)

0.005–0.001 109 113 163 129 114 109

desert ¼ meadow steppe > wetland meadow > typical steppe > terrace tussock grassland > artificial pasture (Table 11.20).

Table 11.20 Community indexes of grasshoppers in different habitats of northern Shaanxi Habitat type Desert steppe Typical steppe Desert Meadow steppe Wet meadow Terrace tussocks Artificial pasture

R 31 23 25 25 24 20 13

Div 2.8016 2.6941 2.5628 2.3394 2.0596 1.6714 1.9168

E 0.9202 0.9321 0.9469 0.8976 0.8945 0.859 0.8724

D 0.0712 0.0769 0.0836 0.1092 0.1482 0.2218 0.1864

Abbreviations: R species richness, Div diversity index, E evenness index, D dominance index. (After Liu and Lian 2001)

11.6.6 Soil Fauna Dong et al. (2008) listed 59 families of soil fauna among 18 orders, 7 classes, and 3 phyla in a variety of shrubby steppe communities dominated by Stipa krylovii, Thymus mongolicus, Artemisia frigida, Artemisia scoparia, and Lespedeza daurica, respectively, in a Ulanqab grassland (Table 11.21). Nematodes were overwhelmingly numerous throughout, accounting for 64.95% on average of the total abundance of all soil animals. Ten groups were commonly found, accounting for 26.24% of the total soil fauna, whereas 72 groups were found occasionally. There were significant differences in the individual abundances of nematodes among different plant communities. Vertically, individuals were less markedly aggregated in the topsoil but instead rather evenly distributed in the 0–20 cm soil profile. The abundance of meso- and microfaunal individuals was significantly related to soil properties, while the relationships of macrofauna with various soil factors were all not significant. The group richness appeared to be rather independent of soil conditions (Table 11.22).

11.7

Soil Microbes

Several studies showed that more than 70% of microbial biomass carbon (MBC) occurred in the 0–20 cm soil layer in a Stipa bungeana steppe distributed in a loessal hilly region, the content of which was mostly between 200 and 350 mg/kg in the various communities (Deng et al. 2012). The standing crop of soil microbial biomass varied considerably among different communities of the shrubby steppe (Table 11.23). Rhizospheric enrichment effects on microorganisms appear to occur commonly in the shrubby steppe. A mean enrichment ratio of 30.3% was estimated in terms of the content of MBC based on data derived from six different communities occurring in the Ningxia portion of the Loess Plateau that were dominated by Stipa bungeana, Agropyron mongolicum, Glycyrrhiza uralensis, Cynanchum komarovii,

356

11

Shrubby Steppe Ecosystem

Table 11.21 Soil faunal composition in Ulanqab grasslands Soil fauna Nemathelminthes (p) Nematoda (c) Annelida (p) Oligochaeta (c) Plesiopora (o) Enchytraeidae Opisthopora (o) Lumbricidae Arthropoda (p) Symphyla (c) Symphyla (o) Scolopendrellidae Arachnida (c) Parasiformes (o) Gamasida (suborder) Erythracidae Acariformes (o) Actinedida (so) Oribatida (so) Araneida (o) Opiliones (o) Chilopoda (c) Geophilomorpha (o) Geophilidae Collembola (c) Collembola (o) Isotomidae Hypogastruridae Tomoceridae Sminthuridae Pseudachorutidae Onychiuridae Insecta (c) Coleoptera (o) Coleoptera larvae Curculionidae Curculionidae larvae Anthicidae Carabidae Carabidae larvae Chrysomelidae Chrysomelidae larvae Nitidulidae Tenebrionidae Cerambycidae Ehteridae Elateridae larvae Ptiliidae Cupedidae Cicindelidae Staphylinidae Staphylinidae larvae Scarabaeoidae Scarabaeoidae larvae

IP (%)

AC

64.95

+++

0.15

+

1.33

++

0.09

+

4.02 0.04

++ +

3.94 1.28 1.93 0.11

++ ++ ++ +

0.41

+

4.66 2.05 0.9 0.64 0.47 0.04

++ ++ + + + +

0.08 0.19 1.28 0.21 1.86 0.08 0.02 0.08 0.02 0.04 0.06 0.06 0.36 0.06 0.04 0.04 0.81 0.77 0.23 0.19

+ + ++ + ++ + + + + + + + + + + + + + + +

Soil fauna Anthribidae Coccinellidae Coccinellidae larvae Meloidae Bruchidae Bruchidae larvae Hemiptera (o) Pentatomidae Coreoidea Coreoidea (nymphae) Miridae Miridae (nymphae) Lygaeidae Lygaeidae (nymphae) Nabidae Anthocoridae Tingididae (nymphae) Piesmidae Reduviidae (nymphae) Diptera (o) Diptera larvae Cecidomyiidae Mycetophilidae Chironomidae Psychodidae Trypetidae Tipulidae Tipulidae larvae Pallopteridae Anthocoridae larvae Aslidae larvae Simuliidae Homoptera (o) Aphidoidea Aphidoidea (nymphae) Jassidae Jassidae (nymphae) Corrodentia (o) Psocidae Thysanoptera (o) Thripidae Thripidae (nymphae) Orthoptera (o) Acridiidae Tetrigidae Hymenoptera (o) Formicidae Ichneumonoidea Ceraphronidae Vespidae Roproniidae Lepidoptera (o) Lepidoptera larvae Noctuidae larvae

IP (%) 0.06 0.09 0.04 0.02 0.04 0.08

AC + + + + + +

0.02 0.08 0.02 0.34 0.02 0.04 0.02 0.06 0.02 0.02 0.02 0.02

+ + + + + + + + + + + +

0.21 0.13 0.08 0.08 0.08 0.02 0.02 0.04 0.02 0.02 0.04 0.04

+ + + + + + + + + + + +

0.23 0.04 0.11 0.02

+ + + +

0.02

+

0.02 0.09

+ +

0.09 0.02

+ +

3.9 0.02 0.02 0.02 0.02

++ + + + +

0.04 0.19

+ +

Note: (p) ¼ phylum; (c) ¼ class; (o) ¼ order. Abbreviations: IP individual proportion, AC abundance class, +++ dominant (IP > 10%), ++ common (IP of 1–10%), + rare (IP < 1%). (After Dong et al. 2008)

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357

Table 11.22 Relationships between soil faunal community traits and environmental factors in Ulanqab grasslands Factor TK TN TP SOM pH SM

Large GR 0.051 0.574 0.255 0.548 0.377 0.782**

IA 0.098 0.287 0.215 0.236 0.239 0.537

Small and medium GR IA 0.127 0.489 0.538 0.791** 0.143 0.189 0.506 0.729** 0.281 0.674* 0.652* 0.799

Abbreviations: GR group richness, IA individual abundance, TK, N, K total nitrogen, phosphorus, potassium, SOM soil organic matter, SM soil moisture. *P < 0.05, **P < 0.01. (After Dong et al. 2008)

Artemisia ordosica, and Sophora alopecuroides, respectively. It was observed that the content of MBC was significantly higher in rhizospheric soils (125.56  10.37 mg/kg of dry soil) than in bulk soils (96.38  8.56 mg/kg). In addition, there were wide variations in the enrichment intensity of MBC with respect to vegetation type, with the enrichment ratio in grass-dominated communities apparently lower than that of non-grass communities, which was regarded to be principally related to rooting depth and structural characteristics of roots and in part to the carbon allocation pattern of the plant species in question (Yang and Liu 2015).

11.8

Algal Crusts

In a degraded shrubby steppe dominated by Tamarix spp. located in the loessal hilly-gully region of Gansu, 53 species of algae were identified in soil crusts collected at different sites, including 34 species of blue algae, 7 of green algae, 10 of diatoms, and 2 of Euglenophyta (Hu et al. 2003). The dominant species throughout were all blue algae (e.g., Phormidium africanum, P. jenkelianum, and Microcoleus vaginatus), while common species included Schizothrix mascarenica, S. fragilis, Myxosarcina concinna, and Lyngbya cryptovaginata (blue algae); Chlorococcum humicola (a type of green algae); and Navicula cryptocephala (a diatom). Species richness varied substantially with habitat type, with 16, 23, 20, and 36 species recognized on clayey loess, gravelly loess, stony loess, and tussock soil, respectively, within this steppe.

11.9

Succession and Utilization

The Thymus mongolicus steppe occurs in bulk on the Loess Plateau and has long been utilized as pasture for livestock grazing, especially in the hilly areas. Forage plants are mainly comprised of composites that are generally of middle-class quality, leguminous plants that are of high quality and especially rich in raw protein, and grasses that are both palatable and high yielding. Annual grasses flourish in rainy years and form major herbage for cattle and sheep. T. mongolicus is a perfumed, oil-rich, economically valuable plant and medicinal herb. Because of its high grazing tolerance, the species is a very important forage plant in degraded pastures. The meat of sheep fed with T. mongolicus is unique and a best seller in the market. T. linearis, a close relative of T. mongolicus, occurs on the northern slopes of the Himalayan Mountains at elevations up to 4000 m, where it can form small stands. The shrubby steppe presumably is a zonal kind of vegetation, with its main body concentrated on the northern Loess Plateau. It is bounded by the Great Wall in the north and the Yan’an region in the south, characterized by a steppe background sparsely interspersed with dwarf woody stands (Zhu 1983a, b). The landform is hilly and gully in nature owing to wind and water erosion of the soils. The heat index decreases from the southeast to the northwest, with an annual precipitation range of 400–550 mm (Zhu and Huang 1993). According to Zhu (1982, 1984), this region was covered by warm-humid broad-leaf forests during the mid-Holocene era, being replaced by pine and cypress coniferous forests during the Tang and Song dynasties when the climate became cooler. During the most recent two centuries, the climate has cooled and dried further. Thus, coniferous forests have begun to retreat in a southeasterly direction, meanwhile accompanied by gradual extensions of shrubby steppes. The recent succession of the vegetation has been driven mainly by human actions, notably cultivation and livestock grazing (Zhu and Huang 1993). Giver that multiple elements act concurrently, a number of successional seres may be found in this region. However, many authors assume that the mainstream forms of intercommunity succession are the various edaphic elementcontrolled ones. With few exceptions, the soil has undergone

Table 11.23 Estimates of the standing crop of soil microbial biomass (0–20 cm soil layer) in different shrubby steppe communities Community Artemisia spp. Imperata cylindrica Cynodon dactylon Stipa bungeana Thymus mongolicus Artemisia frigida Bothriochloa ischaemum Artemisia sacrorum

Location Western Henan Western Henan Western Henan Guyuan, Ningxia Guyuan, Ningxia Guyuan, Ningxia Yanhe, Shaanxi Ansai, Shaanxi

MBC (g/m2) 68.29 159.70 175.05 193.14 113.74 106.23 87.36 32.20

MBN (g/m2) 8.45 16.64 18.28 46.14 9.23 4.18 10.19 3.45

SOC (kg/m2) 3.046 5.535 5.839 8.676 5.276 4.375 1.876 0.506

MBC/SOC (%) 2.24 2.89 3.00 2.23 2.16 2.43 4.66 6.36

References Liu et al. (2016) Liu et al. (2016) Liu et al. (2016) Zhang et al. (2017) Cong et al. (2010) Cheng et al. (2010) Zhao et al. (2014) Wu et al. (2016)

358

repeated cultivation. In such cases, water and wind erosion undoubtedly have carried nutrients out of the system in bulk, leading to the dry and infertile loessial soil status. Starting from barren soils, the following stages of succession are recognized: (1) The pioneering stage: At freshly abandoned fields, Setaria spp. (S. viridis), Artemisia scoparia, and Sonchus spp. are most often the earliest to occur, most of which, except A. scoparia, are worldwide species. Although regionally distributed, A. scoparia can be dominant in the desert steppe and desert communities. This stage usually lasts from 1 to several years. (2) The xerophilous grass community stage: Communities are diversely dominated by various bunchgrasses such as Stipa bungeana, S. grandis, and Cleistogenes squarrosa, and common associates mostly are steppe elements, including Allium polyrhizum, Agropyron cristatum, Artemisia frigida, Iris tenuifolia, Thymus mongolicus, and Cymbaria mongolica. However, most of the species are not the usual components of the shrubby steppe, the presence of which results mainly from the destruction of climax vegetation and the drier soil conditions. Hierochloe odorata and Leymus secalinus are better suited to variable soil moisture, and thus occur vastly at the sites with the poorest water and heat. Agropyron spp. and Poa ochotensis communities are small in area but frequent in their local occurrence, the former being most common in the cooler and drier areas of the western Loess Plateau, while the latter being favored by warmer and more humid conditions and thus being present mainly in the southeastern portion. At valley sides and other humid sectors, Pennisetum flaccidum and Calamagrostis spp. meadows are found at times. The duration of this stage is dominant species specific, depending highly on the effect they pose on soil conditions as well as the competitive capability of the dominant species. For example, S. grandis stands usually last for 3–4 years, because they are more capable of improving soil conditions; Pennisetum flaccidum and Hierochloe odorata stands remain for 4–8 years, owing mainly to their strong competitiveness derived from their rhizomatous regeneration strategy; by contrast, S. bungeana stands are usually retained for 8 more years. (3) The xeromesophilous sage community stage: With substantial amelioration of soil conditions, Artemisia spp., notably A. gmelinii and A. giraldii, becomes dominant in substitution for the earlier grasses. Lespedeza daurica is a common associate at gravelly sites, while Bothriochloa ischaemum, Medicago lupulina, Melilotus spp., and Inula salsoloides gradually invade. However, grasses will not disappear completely in the community. L. daurica or B. ischaemum usually dominates at the late period of this stage, forming separate communities. However, in most cases, B. ischaemum is surpassed in dominance by L. daurica within the community, giving rise to a community co-dominated by both species. This stage can last more than 8 years. (4) The shrubby steppe stage: At this stage, the

11

Shrubby Steppe Ecosystem

climax is characterized by the meadow steppe stand interspersed with sparse woody plants. Shrubs such as Rosa hugonis, Hippophae rhamnoides, Syringa oblata, and Spiraea trilobata are the earlier species, followed by broad-leaf trees such as Prunus armeniaca var. ansu, Ulmus macrocarpa, Pyrus betulifolia, Platycladus orientalis, and Juniperus rigida. Zhu (1993) noted that invasion by woody plants generally does not alter the nature of the community. At eroded sites, Caragana pygmaea and C. microphylla invade during the grass-dominated stage, which may last about 8–10 years before they are replaced by other shrubs or dwarf trees. It is important to note that this succession sequence of the shrubby steppe differs in nature from that of the secondary shrubby grassland (currently classified as warm shrubby tussock grassland) occurring in the southern deciduous forest region (Zhu and Huang 1993). Firstly, in the succession of the tussock grassland, the Artemisia-dominated stage occurs prior to the grass-dominated stage temporally; secondly, dominant grasses most characteristic of this grassland are mesophilous and of warm season, such as Spodiopogon sibiricus, Miscanthus sinensis, and Themeda triandra var. japonica. Abandoned, rain-fed croplands are most commonly found on the poorly drained, wind-eroded, impoverished lower slopes of the northern Loess Plateau region. The vegetal succession of the Stipa bungeana steppe at sites that have undergone the cultivation-abandonment cycle has been extensively studied. Several studies show that Hierochloe odorata is often the first and sole species to invade freshly abandoned fields. This species is a rhizomatous, xerophilous grass that is most favored by the loose and well-aerated soil conditions created by long-term tillage. One of the common associates is Artemisia scoparia, an annual herbaceous sage, accompanied by 3–5 occasional species at times. This stage, characterized by the H. odorata community, lasts about 7 years; present subsequently are Thymus mongolicus, Heteropappus altaicus, and Artemisia annua. These species are better adapted to being buried in the sand and livestock trampling, and thus are rather successful at this stage during which frequent soil erosion occurs following the initial years of abandonment. The species richness increases greatly at this stage, with a total of 22 species observed in varying amounts in the community. This stage usually remains constant for about 10 years. In the subsequent stage, which lasts about 7 years, S. bungeana becomes increasingly dominant, whereas T. mongolicus is reduced to become a subdominant or subordinate species, with Artemisia sacrorum, A. frigida, and Potentilla acaulis as common associates. The community consists of some 40 species, with 90% being perennial herbs. With proceeding succession, T. mongolicus is completely replaced by Artemisia sacrorum as the second most dominant species. Of special note, Stipa grandis and Carex rigescens increase in their dominance considerably

11.9

Succession and Utilization

359

and become important associates in this stage. The species richness decreases pronouncedly at the same time, from 40 species in the last stage down to around 26 in this stage. In addition, just about all species are perennials. Some authors point out that the above two stages could proceed in parallel to each other as separate side paths in the general succession sequence, rather than in a manner of mutual replacement (Zou et al. 1998). The final stage is characterized by the replacement of A. sacrorum by Stipa grandis as the subdominant species, with the S. bungeana + S. grandis community being the climax that usually contains a total of 25 or so species. Important components include A. sacrorum, A. giraldii, and Poa angustifolia that are prominent in the mid-canopy layer, and Carex rigescens, Trigonella ruthenica, and Astragalus scaberrimus in the ground layer. This climax is most typical of the communities occurring on warmer and more humid sites. By contrast, at areas with higher elevations, Stipa grandis sometimes substitutes for S. bungeana as the most dominant or, more accurately, the constructor species, in which case the community is generally regarded as a disclimax community. The same holds for the Carex rigescens + forb meadow community, which often occurs at low-lying sites or stream banks. In general, the succession starting from the abandoned field is originally oriented, for which some 40–50 years are commonly required to arrive at the final stage (Zou et al. 1998). It has been evidenced that reseeding can significantly enhance the succession speed, shortening the length of time needed to arrive at the climax stage. In a degraded S. bungeana pasture resulting from overgrazing, Zou et al. (1998) showed that replanting Astragalus adsurgens into a degenerative stand dominated by T. mongolicus greatly suppressed the dominance of the latter. When A. adsurgens

begins withdrawing from the community, which usually occurs after a few to several years of restoration, S. bungeana regenerates and becomes dominated rapidly. In the meanwhile, Artemisia frigida, A. sacrorum, and Potentilla acaulis, the previously important associates, are also restrained significantly, while the species that were originally insignificant (e.g., Cleistogenes squarrosa, Stipa grandis, and Lespedeza daurica) occur in bulk, leading to substantial improvement in vegetation quality and yield of the pasture. Cheng et al. (1993) noted that the naturally occurring succession would be retained at the stage co-dominated by S. bungeana and T. mongolicus for a long period, being extremely hard to arrive at the climax which is solely dominated by the former species. In stark contrast, it takes no more than 10 years for reseeding-treated succession to attain the climax. The species selected for replanting differ substantially in how they influence the time, content, and direction of the succession. For example, Lespedeza daurica reseeded into similar T. mongolicus stands remained constant for a comparatively longer time before withdrawal than the other species commonly used in this practice. This is because Lespedeza daurica is a wild species, unlike A. adsurgens, and regenerates rather well on its own. In addition, it can coexist with the original associates much better than A. adsurgens, and thus is incompetent in suppressing those that are resistant to progressive succession (Zou et al. 1998). In a Stipa bungeana steppe occurring in Guyuan, Ningxia, a restoration succession chrono-sequence was diagnosed as consisting of six successive stages, characterized by 6-, 16-, 36-, 56-, and 79-year-old stages, respectively, on abandoned croplands (Zou et al. 1997). The changes in basic soil properties and vegetal characteristics with time are summarized in Table 11.24.

Table 11.24 Changes in soil properties and vegetal status of naturally restored grasslands in succession from abandoned croplands Item SOM (g/kg) BD (g/cm3) Sand (%) Silt (%) Clay (%) Soil texture Soil moisture (%) Slope (%) Elevation (m) Aspect Dominant Associate

FA 13.4f 0.97a 22.2 65.5 12.6 Silt loam 9.9

NR6 17.5e 1.02a 20.4 66.8 12.8 Silt loam 12.5

NR16 20.5d 0.96a 16.9 69.5 13.6 Silt loam 7.9

NR36 27.3c 0.95a 13.4 72.7 13.9 Silt loam 8.6

NR56 29.3b 0.38b 14.3 71.4 14.3 Silt loam 6.9

NR79 31.9a 0.84b 11.6 74.1 14.3 Silt loam 7.3

13.3 2037 Semisunny Avena sativa

13.3 2083 Semi-sunny

20.7 2089 Sunny

17.3 2038 Semi-shady

13.3 2074 Sunny

18.3 2028 Semi-shady

L. secalinus

A. sacrorum

A. sacrorum

S. bungrana

S. grandis

H. alataicus, A. scoparia

S. bungrana, A. sinicaa

T. mongolicus, S. bungrana

A. sacrorum, H. alataicus

S. bungrana, A. sacrorum

Anaphalis sinica. Abbreviations: SOM soil organic matter, BD bulk density, FA freshly abandoned cropland; NR6. . . natural restoration for 6. . . years. Means with different letters in the same row are significantly different at P < 0.05 level (LSD). After Zhao et al. (2014) a

360

In this same steppe, Jing et al. (2014) showed that the overall species richness and phytomass (both above- and belowground) were higher in the middle stage of succession with increasing time of livestock exclusion, while the separate plant density, coverage, and aboveground biomass for different plant functional groups showed differential trajectories (Figs. 11.4 and 11.5). Soil organic matter as

Fig. 11.4 Changes in aboveground biomass (a), belowground biomass (b), and species richness (c), of a plant community with time of livestock exclusion. Values are given as means  SE (n ¼ 45). (Adapted from Jing et al. 2014)

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Shrubby Steppe Ecosystem

well as total and available nutrients significantly increased with restoration time. In addition, there were significant interactions between vegetal traits and certain soil properties. Sun et al. (2016) investigated nine previous croplands abandoned for different numbers of years in Ansai County of the central Loess Plateau and found that Artemisia capillaris was the earliest species to appear, followed by

11.9

Succession and Utilization

361

Fig. 11.5 Changes in aboveground biomass of five plant functional groups and the total with time at grazed (right) and enclosed (left) stands. Five plant functional groups include annuals and biennials (AB), perennial bunchgrasses (PB), perennial forbs (PF), perennial rhizomatous grasses (PR), and shrubs and semishrubs (SS). The values are given as means  SE (n ¼ 45). (Adapted from Jing et al. 2014)

Table 11.25 Changes in community traits of a shrubby typical steppe with time of natural restoration Y 5 15 30

C (%) 58  5.38b 83  4.06a 94  2.20a

H (cm) 17.4  0.2b 31.5  0.4a 44.3  0.4a

Grass (%) 17.4  0.2b 31.5  0.4a 44.3  0.4a

NG (%) 82.6  0.2a 68.5  0.4b 53.7  0.4b

CB (g m2) 301.88  25.50b 419.74  51.79ab 496.28  20.21a

RB (g m2) 869.26  114.04a 906.99  81.68a 843.06  171.16a

Abbreviations: Y years of restoration, C coverage, H canopy height, % in terms of biomass, NG non-grass, CB canopy biomass, RB root biomass. Values with different lowercase letters in the same column indicate a significant difference at P < 0.05 level. (After Hao et al. 2016)

Setaria viridis, Heteropappus altaicus, and Lespedeza bicolor with increasing time sequence, with Stipa bungeana dominating the final stage of succession. SOC, total N, and clay contents increased significantly with increasing abandonment time, being most significant in the topsoil. In a shrubby typical steppe of northern Shaanxi, Hao et al. (2016) found that the restorative succession in an abandoned cropland followed the order Agropyron cristatum community ! Helictotrichon schellianum community ! Poa subfastigiata community. Community traits improved substantially with restoration time, while species richness, evenness, and diversity dropped significantly after 15 years of restoration (Table 11.25). The soil water content usually decreases degree by degree from early- to late-successional habitats of abandoned croplands due to increasing water consumption by vegetation. Accordingly, late-successional species must have a stronger capability to resist drought stress than the earlysuccessional ones. In an array of abandoned crop fields in the mountain region of Yuzhong County, Gansu, Yu et al. (2015) observed that root traits between early- and latesuccessional species differed significantly. For example, the early-stage species Artemisia annua had significantly fewer taproots but more lateral roots, whereas Stipa breviflora, a late-stage species, had more abundant deeper roots but less lateral and adventitious roots. By contrast, mid-stage species such as Heteropappus altaicus, Artemisia frigida, and Leymus secalinus were intermediate in this regard. All of these as well as other data point to the notion that earlystage species must strategically develop more lateral roots

in order to more effectively absorb limited nutrients from the poor soil of the recently abandoned fields. However, with substantial improvements in soil fertility, the latesuccessional species shift to cope with increasingly consumed soil water, and thus they must possess deeper penetrating roots to compete with the earlier succession species for soil water. In a steppe originally dominated by Stipa bungeana, Wang and Zhang (2009) examined the variations in carbon reserves both belowground and aboveground in a series of abandoned crop fields with different durations of abandonment. They found that the aboveground carbon biomass decreased initially and started to increase in the third year of abandonment until the period from years 22 to 32, when the aboveground carbon biomass remained at the first steady state. This was followed by the second increasing-then-stable cycle from years 40 to 60 after abandonment. The dynamics of root carbon biomass were generally similar to those of the aboveground carbon biomass. Compared with croplands, the recovered grassland had a lower soil organic carbon reservoir at the beginning period (from the 1st to the 12th year). However, from the 15th year on, soil organic carbon storage began to surpass that of the cropland and increased stably ever since (Table 11.26). Of special note, the S. bungeana steppe is also occasionally found in the Horqin sandy steppe of Inner Mongolia. Where the soil is eroded due to overgrazing, the Thymus mongolicus + Artemisia frigida stand becomes prominent, with S. bungeana, Cleistogenes squarrosa, and Lespedeza daurica decreasing (Ren 1990).

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Shrubby Steppe Ecosystem

Table 11.26 Changes in carbon storage in vegetation and soil across different successional stages of a rehabilitated grassland starting from abandoned croplands YA (a) 1 2 4 7 10 12 15 22 28 32 40 50 60

Carbon storage in vegetation TVC (g/m2) Canopy (%) 144.83 36.68 70.61 31.61 96.31 36.85 78.21 44.19 164.77 27.47 266.95 10.75 297.77 8.05 328.10 21.16 318.93 19.43 432.76 14.91 455.57 20.74 513.43 17.61 502.31 19.54

Root (%) 63.32 68.39 63.15 55.82 72.53 89.25 91.95 78.84 80.57 85.09 79.26 82.39 80.46

Carbon storage in soil TSC (kg/m2) 0–30 cm (%) 4.494 28.15 5.159 22.31 4.333 25.85 4.827 24.57 4.769 25.85 4.339 27.59 9.419 22.38 6.708 34.20 12.344 30.48 14.899 51.02 17.061 41.10 18.189 38.62 19.278 39.77

0–90 cm (%) 67.85 62.78 59.50 62.30 64.29 66.17 59.37 72.36 65.72 83.32 70.55 77.00 72.07

Total (kg/m2) 4.639 5.230 4.429 4.905 4.935 4.605 9.717 7.037 12.663 15.332 17.517 18.702 19.781

Abbreviations: YA years of abandonment, TVC total vegetal carbon storage, TSC total soil carbon storage of the 0–150 cm profile. (After Wang and Zhang 2009)

In the northern Ningxia S. bungeana steppe, Cynanchum komarovii and Peganum nigellastrum are considered the indicator species of desertification. At the initial stage of desertification, sand cover is rather thin or seasonally found on the ground, and the species composition does not change much. Usual species, such as S. bungeana, S. breviflora, Cleistogenes squarrosa, Lespedeza potaninii, Glycyrrhiza spp., and Oxytropis aciphylla, are mostly retained in the community. However, annual forbs such as Artemisia scoparia, Corispermum declinatum, Tribulus terrestris, and Eragrostis minor increase noticeably. Moving into the mid-stage, the above species generally retreat, while those better suited to sandy conditions enter the community and become dominant, such as Pennisetum flaccidum, Leymus secalinus, and Agropyron mongolicum, accompanied by earlier increasers. At the final stage when the soil has become seriously desertified, Artemisia ordosica dominates the community, with Sophora alopecuroides, Thermopsis melilotoides, Lespedeza potaninii, and Cynanchum komarovii as the most common associates (Chen and Liu 1995).

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363 Wang YF, Yong SP, Liu ZL (1985a) Vegetation Zones. In: Inner Mongolia-Ningxia Comprehensive Survey Team of CAS (eds) Vegetation of Inner Mongolia. Science Press, Beijing, pp 420–466 Wang YF, Yong SP, Liu ZL, Kong DZ, Zhao XY (1985b) Steppe vegetation., In: Inner Mongolia-Ningxia Comprehensive Survey Team of CAS (eds) Vegetation of Inner Mongolia. Science Press, Beijing, pp 427–644 Wang GW (2004) Protection and utilization of snake resources in Longdong, Gansu. Sichuan J Zool 24(3):407–409 Wang W, Peng SS, Fang JY (2008a) Biomass distribution of natural grasslands and its response to climate change in north China. Arid Zone Res 25(1):90–97 Wang YL, Liu H, Lian ZM (2008b) Orthopteran diversity in ecologically restored area of Wuqi County, Shaanxi. Chin Bull Entomol 45(4):629–634 Wang JF, Wang XP, Li XM, Liu GX (2010) Influence of landuse on species diversity of Carabid beetles (Coleopeta, Carabidae) in Bashang region, Hebei, Northern China. Acta Entomol Sin 53 (10):1127–1134 Wang JM, Zhang XC (2009) Changes of carbon storage in vegetation and soil during different successional stages of rehabilitated grassland. Acta Pratacul Sin 18(1):1–8 Wang ZX, Zhang YH, Wang XP (2015) Diversity and community structure of beetles in Yunwu Mountain grassland. Practacult Sci 32(7):1156–1163 Wu JP, Han XH, Xü YD, Ren CJ et al (2016) Ecological stoichiometry of soil and soil microbial C, N, P under grain-for-green program in loess hilly region. Acta Agrestia Sin 24(4):783–792 Yang YY, Jia YX (2014) Analysis of the fauna composition of Hemiptera in Yunwu Mountain Nature Reserve of Ningxia. J Agric Sci 35(4):42–44 Yang Y, Liu BR (2015) Distribution of soil nutrients and microbial biomass in rhizosphere versus nonrhizosphere areas of different plant species in a desertified steppe. Acta Ecol Sin 35 (22):7562–7570 Ye WB, Huang ZH, Xin TT, Liu FS, Pang SW (2016) A preliminary investigation on snake resources in Liangdang County, Gansu Province. J Mianyang Teache Coll 35(8):64–67 Yu MX, Fang W, Yao GQ, Zhao WN et al (2015) Comparison of seminal root traits of five successional species in abandoned arable lands in northern mountainous areas of Yuzhong County. Acta Ecol Sin 35(10):3252–3257 Zhang Y, Liu JS, Zahng JX, Peng WS (1997) Fauna and geographic division of Loess Plateau Glires (Rodentia and lagomorpha). J Shaanxi Norm Univ 25(Suppl):4–16 Zhang N, Liang YM (1999) Comparative study on belowground growth and their relationships with soil moisture of two kinds of natural grasslands in loessal hilly regio. Acta Bot Boreal Occident Sin 19 (4):699–706 Zhang ZN, Wu GL, Wang D, Deng L et al (2014) Plant community structure and soil moisture in a semi-arid natural grassland of the Loess Plateau. Acta Pratacul Sin 23(6):313–319 Zhang H, Ye CL, Wang Y, Guo H (2017) Characteristics of soil microbial respiration and its response to temperature change in different soil depths of Yunwu Mountain grassland. Pratacult Sci 34(2):224–230 Zhao N, Zhuang Y, Zhao J (2014) Effects of grassland management on soil organic carbon and microbial biomass carbon. Pratacul Sci 31 (3):367–374 Zhu ZC (1982) Community kinds in the forest steppe region of north Shaanxi (1): woodland and shrubby grassland. Chin J Grassl 2:1–8 Zhu ZC (1983a) The scope of forest steppes on the Loess Plateau. Acta Phys Sin 7(2):122–131 Zhu ZC (1983b) The range of forest steppe zone on the Loess Plateau of the northern part of Shaanxi Province. Acta Phytoecol Geobot Sin 7:122–132

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11

Shrubby Steppe Ecosystem

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Sandy Grassland Ecosystem

Abstract

This chapter focuses on Chinese sandy grassland ecosystems. It introduces in brief the areal extent and provincially based distribution of this ecosystem type; simply discusses the relevant physical features and climatic characteristics at a regional scale; elaborates in great detail upon the flora, fauna, and microflora composing the various sandy grassland ecosystems; and describes in much greater detail the major formations or formation groups of the sandy grassland vegetation nationwide. It also summarizes the standing crops of canopy and root biomass and their allocation pattern of certain important communities. In addition, it expounds on the succession characteristics and their responses to the management and utilization steps of certain sandy grassland ecosystems. Keywords

Vegetal formation · Flora · Fauna · Microorganisms · Root-to-canopy ratio · Succession · Ecological sequence

Chinese sandy grasslands, or sandlands, are the plant community assemblages that occur on the aeolian sandy soil and are mainly interspersed within zonal steppes, while not including those of either desertified steppes or psammophilous vegetation present in zonal deserts (Yong and Guo 1985). The genesis of the sandlands was mainly associated with the alluvial and diluvial deposition actions of ancient rivers during the Late Tertiary period, and was in part influenced by the physical weathering of sandy rocks during the Cretaceous epoch. Geological uplifts and interglacial droughts during the Quaternary period significantly enhanced the process through the massive transportation and sieving of eroded substrata by wind, resulting in the presence of earlystage sandlands. The aeolian process undoubtedly has played a more dominant role in the formation and distribution of the

# Springer Nature Singapore Pte Ltd. 2020 L. Li et al., Grassland Ecosystems of China, Ecosystems of China 2, https://doi.org/10.1007/978-981-15-3421-8_12

12

sandy landforms and their physiography in more recent stages (Zhu 1986). Plant adaptation to sandy environments is characterized by the following aspects: firstly, they are generally much better suited to sand burial, wind exposure, and erosion. To cope with the harsh conditions, the plants usually have a fastgrowing, wide-spreading, and deep-penetrating root system, which mostly forms glue-like sandy films or coatings on the surface of fibrous roots and on the hairs of taproots. The most characteristic psammophytic plants of this kind are Agriophyllum squarrosum, Corispermum spp., Pugionium spp., Stilpnolepis centiflora, and Psammochloa mongolica. Secondly, they usually bear close, white-gray, short hairs on their greatly shrunken leaves and across their significantly shortened, thinned twigs to reflect sunlight, while their basal stems become substantially lignified, all of which are means to deal with the hot and highly variable heat conditions and to preserve more water in their organs. Of these, Artemisia spp., Olgaea leucophylla, and Panzeria alaschanica are most representative. Thirdly, they usually evolve special mechanisms to survive on the extremely nutrient-poor soil, such as high nutrient-use efficiency, ability to conduct nitrogen fixation on their own, and making use of rainfall-deposited nutrients.

12.1

Distribution and Natural Conditions

Chinese sandy grasslands are found mainly in Inner Mongolia, Gansu, and Ningxia (Table 12.1), of which the Hulun Buir sandland, Horqin sandland, Hunshan Dak sandland, Mu Us sandland, and Qubuqi sandland are most prominent and best known (IMNCST 1985). In addition, small areas of sandlands are interspersed in various steppes, such as those occurring in the northern piedmont of the Yinshan Mountains and the western piedmont of the Greater Hinggan Ridge, although they are still not conspicuous at

365

366

12 Sandy Grassland Ecosystem

Table 12.1 Regional distribution of Chinese sandy grasslands Province Inner Mongolia Jilin Shaanxi Ningxia Gansu Total

Area (hm2) Meadow 161,169 33,178

194,347

Typical 7,496,032 221,731 375,791 2954

Desert 1,448,630

628,825 128,752 2,206,207

8,096,508

present. Three land patterns are ubiquitously found within the sandlands, i.e., mobile sand dunes, semifixed sand dunes, and fixed sand dune fields. The western Liaohe sandland, also known as the SongNen sandland, covers an area of some 10,800 km2 in the middle and lower reaches of the Liaohe River in northeast China (Zhang et al. 1998). It tilts from 800 m in the west to 200 m in the east. Sand dunes in the north are low (2–3 m high) and level, forming a gently rolling landscape, whereas those occurring in the south are noticeably higher and steeply fluctuating. Given the proximity to the sea and receipt of more humid air currents, precipitation in the area is relatively high, attaining 300–450 mm annually, and the mean annual temperature is usually between 4 and 6
C, with the annual cumulative temperature 10
C more than 2400
C on average. Thus, the climate is generally mild and semi-humid. Fixed and semifixed sand dune fields along with inter-dune meadows occupy more than 80% of the total sandland area, while the rest is occupied by mobile sand dunes (Guo et al. 1996). The Hulun Buir sandland lies in the upper and middle reaches of the Hailar River, at elevations from 600 to 750 m. It ranges in a roughly northwest-to-southeast direction, covering an area totaling 4780 km2. Fixed and semifixed sand dunes thereof are commonly 10–15 m in height, and the thickness of sand layers typically exceeds 50 m. The climate is transitional from semi-humid to semiarid. Mean annual temperatures are between 2 and 0
C, monthly minimal temperatures averaging 28.3
C that occur in January, with absolute minimums of around 50
C recorded frequently in recent decades; the hottest month is July, with 20.9
C on average. The frost-free season lasts between 100 and 110 days, and the annual cumulative temperature 10
C is between 1800 and 2000
C. The annual precipitation is around 350 mm on average, with 80% falling during the growth season (Table 12.2). The Hunshan Dak sandland, also called the Lesser Tengger sandland, is situated in the middle portion of the Xilin Gol grassland region, ranging 400 km from west to east and 50–150 km from north to south, with an area totaling 42,300 km2 (Zhang et al. 1998). The terrain tilts from the southeast to the northwest but is mostly at elevations between

Total 9,105,831 254,909 375,791 631,779 128,752 10,497,062

Prop. (%) 86.7 2.4 3.7 6.0 1.2 100

1100 and 1300 m. The area is forcefully influenced by the northwesterly wind, and thus the ridges of the sand dunes are all arranged in roughly northwest-to-southeast directions. One of the most characteristic aspects of this sandland is its highly diverse flora, wherein about 32 woody plant species and more than 200 herbaceous species are identified (Yong and Guo 1985). This is largely attributed to its special geographic location, in that it is both a vegetation-intersecting area of the typical, meadow, and desert steppes and an agropastoral ecotone. The Mu Us sandland lies on the southeastern corner of the Ordos Plateau, bordering the Loess Plateau on the south and east, with a total area of some 32,100 km2 (Zhang et al. 1998). Its water and heat conditions are the most favorable of its kind, with mean annual temperatures from 6 to 8
C and a frost-free period of 130–160 days. The mean annual precipitation ranges from 250 to 320 mm in the west and from 400 to 440 mm in the east.

12.2

Soils

Most dominant in Chinese sandlands of the temperate steppe biome are various aeolian sandy soils, the total area of which approximates 12.68 million hm2 (CNSSO 1998), with two-thirds (8.88 million hm2) occurring in the Inner Mongolian steppe region (IMSSO 1994). The steppe aeolian sandy soil is a major kind of soil of the sand dune fields. It has experienced a long period of the stable soil genesis process, and therefore has rather well-developed semifixed and fixed soils. However, they are still vulnerable to human disturbances. Once heavily utilized or disturbed, they are prone to rapid desertification. The environment is characterized by cold climates, with dry and windy days prevalent throughout the year. Evaporation usually exceeds precipitation by 2–10 times in different areas. Under these conditions, woodland, shrubland, and steppe communities occur concurrently, forming a rather unique landscape featured by an admixture of various vegetation types, best known as the temperate savanna. The soil profile is poorly differentiated, with only two layers apparently occurring, i.e., the humus layer and the parent material layer. The humus

365–543

425–435

0.8–1.0

0.9–2.2

0.5

1.2–1.7

0.9–1.5

1.2–2.0

1.1–1.7

0.9–1.7

1.6 2.3–2.6

2.2–3.7

2.0–3.4

2.5–3.0

2.4–3.2

1.9–3.8

0.9–1.4

Southern XG

JiningZhangbei Northern XG

Horqin

Weichang

Eastern Ordos

Hulun Buir

Western XG

Daqingshan NW Ordos

Ulan Qab

HD Ningxia

Hetao

Yinchuan

GN boundary

Songnen

90

72–87

84–88

82–86

79–86

81–85

81 83–86

73–87

76–88

75–93

84–88

84–87

62–76

71–83

77–88

GSP (%) 65–82

50–90

80–130

115–155

85–145

130–150

75–115

68 95–140

50–110

40–80

45–155

60–90

60–90

25–30

70–120

50–80

CDD (d) 40–95 19–20 18–21 16–17 22–34

21 to 17 14 to 17 26 to 25 14 to 13 1 to 12 15 to 8 27 to 22 23 to 15 17 13 to 13 21 to 16 11 to 8 16 to 13 10 to 8 10 to 8 20 to 16 21–23

23–24

23

22–23

22–24

21–23

19 22–24

18–22

20–21

21–25

21–23

Jul. 17–19

Jan. 19 to 15

Heat conditions Temperature (
C)

2.5–4.6

7.7–8.7

8.1–9.0

4.4–6.8

6.3–8.9

1.4–4.5

170–190

2.1 to 0.3 1.0 to 4.4 2.4 5.6–6.7

150–180

105–125

105–115

130–150

110–135

150–170

170 130–140

150–180

110–160

130–140

130–150

>196

150–160

170–180

W 165–180

5.2–8.6

4.7–7.0

3.2 to 3.3 3.4–6.8

0.2 to 2.4 0.5–5.0

Annual 1.2–3.0

DS (d)

40–90

35–85

60–80

50–70

45–85

25–67

13 45–75

8–32

9–25

40–80

45–60

40–80

1–2

4–30

10–20

S 0–25

140–160

160–180

170–180

145–160

155–180

130–150

130 150–170

115–150

110–125

145–175

145–170

140–170

90–95

105–145

110–130

WS 105–130

2600–2900

2950–3450

3300–3400

2700–3100

2800–3400

2300–2800

2120 2700–3100

1900–2500

1900–2200

2600–3600

2500–3200

2600–3200

1350–1420

1800–2800

1800–2200

MCT (
C) 1650–2100

68–104

20–70

27–61

29–77

32–60

85–170

76–107

66–165

65–123

26–68

37–109

56–122

45–65

WD 94–134

NE, NW, SW WNWWSW

NWN, NE, SE WSW-W

WNWWSW WNWWSW WNW-N

WNWWSW WNWWSW

WNWWSW WNWWSW WNW

WNW-N

Direction WNWWSW

Sand movement WS (m s1 d1)

DS (%)

Abbreviations: XG Xilin Gol; NW northwestern; GN Gansu and Ningxia; MAP mean annual precipitation; GSP growth season precipitation; CDD cold-dominant days; MACT mean annual cumulative temperature; WD windy days; D wind direction. (Adapted from Zhang et al. 1998)

370–480

155–305

185–230

165–221

190–280

130–220

230 210–280

210–250

230–320

310–470

370–460

320–460

325–365

Aridity 0.7–1.1

Region Hunshan Dak

MAP (mm) 310–405

Water conditions

Table 12.2 Climatic parameters of major locations of Chinese sandlands

12.2 Soils 367

368

12 Sandy Grassland Ecosystem

Table 12.3 Physiochemical properties of different kinds of steppe aeolian sandy soils Site NM

SK M

MU

M

MU

SF

HD

SF

HQ

SF

HB

F

HD

F

HB

W

XU

W

Depth (cm) 0–20 20–120 0–15 15–150 0–25 30–40 0–10 50–60 0–40 40–140 0–15 30–40 40–95 5–8 20–30 60–70 0–14 60–70 100–110 5–8 60–70

SOM (g/kg) 0.3 0.6 3.5 1.0 2.3 4.1 3.1 0.6 5.0 2.2 7.1 4.8 0.7 7.6 2.7 0.9 12.4 7.9 4.4 8.3 4.7

TN (g/kg) 0.03 0.05 0.14 0.05 0.14 0.16 0.06 0.32 0.14 0.33 0.27 0.07 0.30 0.19 0.09 0.36

0.40

TP (g/kg) 0.09 0.09 0.45 0.4 0.53 0.41 0.10 0.20 0.34 0.16 0.55 0.59 0.17 0.82 0.32 0.12

TK (g/kg) 16.0 17.0

3.0 17.0 28.1 28.1 28.0 26.3 24.5 24.6

0.51 0.27

31.5 10.6

pH 6.6 6.4 8.0 8.0

8.6 8.6 7.7 7.2 7.0 7.0 7.4 8.3 8.7 8.8 6.2 6.7 6.8 8.3 8.8

Particle (%) >0.02 0.02–0.002 87.6 9.4 86.5 10.6

0.02 20 cm

340.4 58.9 37.6 818.3 2009.2 192.5 23.0 163.6 105.5 224.2 2598.7 2318.5 390.3 117.3

Total 246.44 155.8 382.3 295.0 323.6 120.8 204.6

10.45 1.67 0.80 1.18

3.88

R/Ce 1.05 2.07 2.00 2.16 1.70 2.00 1.51

Jin et al. (2013)

Zhou et al. (2015)

Ma et al. (2010)

Hu et al. (2017)

Source Wang and Li (1994) Cheng et al. (2001)

Note: aTreatment; bsoil depth; ccanopy biomass; droot biomass; eroot-to-canopy biomass ratio; fmobile sand dune; gsemifixed; hfixed sand dune; iartificial pasture of Hedysarum; jartificial pasture of Astragalus adsurgens; ksandy steppe; llightly desertified; mmoderately desertified; nheavily desertified

6. Corispermum spp. Agriophyllum pungens

Horqin

3. Agrioph. squarrosum Artemisia halodendron 4. 5 stands Artemisia ordosica Hedysarum spp. Salsola collina Corispermum spp. 5. Artemisia halodendron Agrioph. squarrosum

Junggar Ct 40
12’-13’N 111
050 -117
070 E

Location Qubuqi Mu Us, 1355 m 39
02’N 109
510 E

Community 1. Artemisia ordosica 2. Ordos sandland Stipa bungeana Artemisia ordosica Cynanchum komarovii

a

Table 12.10 Standing crop of phytomass and its allocation between canopy and roots in different communities of the sandy grassland

12.5 Fauna 377

378

12 Sandy Grassland Ecosystem

Table 12.11 Herpetofauna of Yulin sandland, Shaanxi Class Amphibia

Reptilia

Species Bufo bufo gargarizans B. raddei Rana amurensis△ R. nigromaculata R. temporaria chensinensis Trionyx sinensis Phrynocephalus frontalis Gekko auriverrucosus△ Eremias argus E. multiocellata multiocellata△ E. m. yarkandensis△ Coluber spinalis Dinodon rufozonatum Elaphe dione Natrix tigrina lateralis Agkistrodon halys intermedius

Note: “△” newly recorded in Shaanxi Province. (After Song 1985)

Zhang et al. (1983) listed 64 species of birds to occur in this region, which belong to 22 families and 12 orders. Of these, ten species are permanent residents, and 33 are summer breeders, while the rest are migrants or winter residents. Dominant and common species include Falco vespertinus, Aquila chrysaetos, Streptopelia spp., Athene noctua, Galerida cristata, Calandrella acutirostris, Pica pica, Corvus monedula, C. frugilegus, Emberiza cioides, Alectoris

graeca, and Passer montanus, all of which are steppe or desert species. In terms of feeding behavior, 33 species are insect feeders and 6 are vole preyers, while the others are generally omnivorous and feed on both insects and seeds or fruits. In the Hunshan Dak sandland, the permanent residents are Perdix dauurica, Phasianus colchicus, Streptopelia decaocto, Pica pica, Corvus dauuricus, C. corone, and Passer montanus, while 6 important bird species breed here during the summer. In addition, 40 odd species of migrant birds inhabit inter-dune wetlands, ponds, and lakes (Wu et al. 2008). Of these, wading birds contain 26 species, followed by swimming birds (13), songbirds (10), raptors (5), terrestrial birds (3), and scansorial birds (1). In a Hulun Buir woody sandland, 19 species of birds were observed, with the Pinus sylvestris woodland having the largest number of species (13), followed by the Caragana microphylla stand (10), the Pinus sylvestris plantation (7), the Artemisia frigida + Thymus serpyllum stand (6), and the Betula platyphylla plus Populus davidiana woodland (2). The abundances varied significantly among species and habitats (Table 12.12). In various grassland ecosystems including steppe, sandland, meadow, and agropastoral ecotone, 42 species of raptors have been recorded nationwide, with 9 being permanent residents (Table 12.13). Of all of these, the most abundant are Buteo hemilasius, Falco tinnunculus, Athene noctua,

Table 12.12 Bird species and their abundances among different biotopes of a woody sandland Species Cuculus canorus C. saturatus Caprimulgus indicus Alauda arvensis Motacilla cinerea Anthus hodgsoni Lanius cristatus Garrulus glandarius Corvus corone Phylloscopus schwarzi Ph. borealis Parus ater P. montanus Carduelis sinica Carpodacus erythrinus Loxia curvirostra Emberiza leucocephala E. cioides E. tristrami

A – – – – – 14(0.7) – – – – – – 7(0.35) – – – – – – 21(1.05)

B 1(0.04) – – 33(1.32) – 29(1.16) – – – 1(0.04) 5(0.2) – – – – 15(0.6) – – – 84(3.36)

C 1(0.04) – 4(0.16) – 2(0.08) 15(0.6) – 1(0.04) 2(0.08) 2(0.08) 28(1.12) – 1(0.04) 1(0.04) – – – – – 57(2.28)

D 3(0.12) – – – 1(0.04) 10(0.4) 5(0.2) 2(0.08) 4(0.16) 1(0.04) – 2(0.08) 8(0.32) 2(0.08) 90(3.6) 20(0.8) 7(0.28) – – 157(6.28)

E 1(0.04) 1(0.04) – – – 9(0.36) – – – 1(0.04) 8(0.32) 3(0.12) – – – – – – 6(0.24) 29(1.16)

Note: The number outside of the parentheses is the number of individuals observed, while that in parentheses is the density value (ind./hm2). Abbreviations: (A) Populus davidiana woodland; (B) Artemisia frigida + Thymus serpyllum stand; (C) Caragana microphylla stand; (D) Pinus sylvestris woodland; (E) Pinus sylvestris plantation. (After Wang et al. 2005)

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379

Table 12.13 Major raptor species and their distributions in Chinese grasslands Species Milvus migrans Accipiter gentiles A. nisus Buteo buteo Aquila chrysaetos Gypaetus barbatus Falco cherrug F. subbuteo F. tinnunculus

TA 350,000 250,000 250,000 180,000 27,000 92,000 67,000 100,000 840,000

IM Xinjiang (total ind.; density –ind./km2) 4123/0.0046 133,615/0.082 6158/0.0206 3259/0.0107 18,907/0.0785 1161/0.04 82,708/0.1034 9536/0.0073 1441/0.0048 5610/0.0047 15 22,081/0.0306 55,129/0.03 6185/0.0088 43,143/0.052 15,956/0.0199 536,917/1.445

Tibet

Northeast

3458/0.0058 1886/0.0314 4877/0.1393 5363/0.0153 1957/0.0039 7500/0.0214

5359/0.0107 17,218/0.02–0.06 12,008/0.0178–0.0586 13,775/0.0283–0.0566 907/0.0003–0.042

17,965/0.0454–0.081 50,216/0.0455–0.1839

10,933

Abbreviations: TA total abundance (ind.); IM Inner Mongolia. (After Yu et al. 2009)

Table 12.14 Rodential species and their distributions in Ordos sandlands Order Rodentia

Family Sciuridae

Cricetidae

Muridae Dipodidae

Total

Species Citellus dauricus brandti C. alaschanicus Eutamias sibiricus Phodopus roborovskii Cricetulus barabensis C. eversmanni C. triton C. migratorius Meriones unguiculatus M. meridianus Ondatra zibethicus Microtus maximowiczii Rattus norvegicus Mus musculus Stylodipus telum Salpingotus kozlovi Dipus sagitta Allactaga sibirica

E. Qubuqi N 46

2421 989

% 0.61

32.17 12.31

7 1409

0.93 18.72

19 167

0.25 2.22

2261 206 7525

30.05 2.74 100

W. Qubuqi N % 52 5.04

320 19 9

30.91 1.79 0.85

4 28 116

0.38 2.2 11.17

2 4 316 172 1036

0.16 0.4 30.54 16.56 100

Mu Us N

%

72 5 289 34

0.58 0.04 2.31 2.72

14

0.11

10,320 138 4 1 160 913

82.45 1.1 0.03 0.01 12.78 7.29

415 152 12,517

3.32 1.21 100

Abbreviations: E eastern; W western; N number of individuals observed. (After Wang et al. 1999; Wu et al. 1994; Chen 1965)

and Asio otus; common species are Milvus migrans, Otus bakkamoena, and Asio flammeus, while occasional species are Bubo bubo, Strix aluco, and S. uralensis (Wang et al. 2002).

12.5.4 Rodents Eighteen rodential species have ranges in the Ordos sandlands, of which Meriones unguiculatus is most dominant in the Mu Us sandland, while Phodopus roborovskii, Dipus sagitta, and Meriones meridianus are most frequent and abundant in the Qubuqi sandland (Wang et al. 1999). Major species of rodents ranging in the various sandlands on the

Ordos Plateau are summarized in Table 12.14, along with their relative abundances. Temporal dynamics in population size differ considerably among the different populations in these sandlands. Hou et al. (1998) observed that the seasonal patterns of Dipus sagitta and Allactaga sibirica were both rather regularly fluctuating and characterized by a single-peaked trend, whereas those of Meriones meridianus and Cricetulus barabensis were apparently multi-peaked. By contrast, the seasonal trend of the Phodopus roborovskii population was basically level in most years but would steeply fluctuate in a certain year. The total abundance of the rodent community also varied markedly from year to year, with the maximum occurring in different months of different years. It can be seen from

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Fig. 12.3 Temporal variations in abundance of certain rodent populations ranging in the Ordos sandlands. (After Hou et al. 1998)

Fig. 12.3 that some of the populations fluctuated slightly both intra- and inter-annually within several years yet pronouncedly on a 3- to 5-year cycle, whereas others displayed a regular and distinct seasonal pattern with slight inter-annual changes in abundance.

Shi (1991) reported 12 rodent species to have ranges in a semiarid sandland region, which were associated with different kinds of vegetation. Of these, Allactaga sibirica, A. bullata, and Cardicoranius paradoxus occurred mainly in the Caragana–Stipa klemenzii sandland, whereas Phodopus

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381

Table 12.15 Species composition and distribution of Glires in different habitats of the Bahrain sandland Species Lepus capensis Ochotona daurica Eutamias sibiricus Citellus dauricus Rattus norvegicus Mus musculus Apodemus peninsulae Cricetulus barabensis Phodopus roborovskii Microtus gregalis Ondatra zibethicus Meriones unguiculatus Myospalax aspalax M. psilurus Dipus sagitta Allactaga sibirica Total no. of species

MM + + + + + + +

LM +

PG +

SD +

+ + +

+ + +

+

+ +

+ + + + + +

+

+ + +

+

+ + 8

+ 8

+ 10

7

Abbreviations: MM mid-elevation mountains; LM low mountains; PG plain grasslands; SD sand dune fields. (After Guo et al. 1994)

roborovskii, Stylodipus andrewsi, and Salpingotus kozlovi were more often found on the active or semifixed sand dunes scattered with sparse patches of Nitraria spp. and Artemisia soongorica. Wu et al. (1999) observed that Dipus sagitta, Meriones meridianus, and Phodopus roborovskii mainly inhabited Artemisia ordosica stands in the Mu Us and Hunshan Dak sandlands. In various stands of the Horqin sandland, Guo et al. (1994) reported the presence of 16 rodent species, belonging to 6 families and 2 orders (Table 12.15). The typical steppe occurring on the plains has the largest number of species, whereas sandy stands contain the least species. Guo et al. (1994) showed that the abundance and seasonal dynamics of even the same species may differ considerably within different habitats (Fig. 12.4).

12.5.5 Insecta On Ordos sandlands, Yu et al. (2001) showed that beetles were the most dominant group of Insecta, which accounted for 45.8% of the total abundance of the insects collected, with families Tenebrionidae and Carabidae collectively constituting 92.8% of the total abundance of beetles (Table 12.16). They revealed that the species distribution was principally determined by the precipitation gradient and vegetation type, with a positive correlation between precipitation and beetle species diversity and evenness and a negative correlation between precipitation and the abundance of beetles in this region.

Fig. 12.4 Population dynamics of Meriones unguiculatus in different biotopes of the Horqin sandland. Note: (I) river-flooded flat, (II) sporadic pasture among croplands, (III) semidesert rangeland, (IV) sandland. (After Qin 1984)

Consecutive studies across the whole Ordos Plateau have documented 72 species of darkling beetles (Tenebrionidae), belonging to 25 genera, 9 tribes, and 2 subfamilies (Zhao and Ren 2014). The predominant tribes are Opatrini, Tentyriini, Blaptini, and Pimeliini, which altogether contain 65 species and 20 genera, accounting for 90.3% and 80.0% of the region’s total numbers of species and genera of darkling beetles, respectively. The predominant genera are Microdera (11 spp.), Blaps (10), Anatolica (9), and Melanesthes (8). Zoogeographically, the darkling beetles of the Ordos Plateau all belong to the Mongol-Xinjiang element, of which 22 species are also north China species, and 16 species are shared with Qinghai-Tibet and other regions. The total number of darkling beetle species occurring on the Ordos Plateau accounts for about 3.6% of the total fauna of darkling beetles nationwide (roughly 1980 spp.), with 53 species in common with the Inner Mongolia Plateau (241 species), 20 shared with the Loess Plateau, and 7 species endemic to this region. On the Ordos Plateau, its four subregions Mu Us sandland, Qubuqi sandland, Zhuozishan desert steppe, and loess hilly shrubby steppe each contains 68, 26, 16, and 20 species, respectively (Zhao and Ren 2014). He et al. (1988) showed that terricolous insects most commonly inhabited the sand dune fields of the Yanchi sandland among a total of some 50 insect species present here, of which Blaps rugosa and B. davidea were most characteristic. Although primarily living in soils, these insects usually hibernate in or under litter of sand-dwelling plants, feeding on both live plant materials and fallen leaves or seeds. Some species, such as Coccinella septempunctata and Lygaeus equestris, may migrate along with gusts of wind. In grass stands formed on the abandoned croplands

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Table 12.16 Species composition and relative abundance of insects and other invertebrates occurring in Ordos sandlands Group Myriapoda Arachnida Araneida Acarina Insecta Dermaptera Neuroptera Orthoptera Homoptera Hemiptera Coleoptera Carabidae Carabus Others Cicindelidae Staphylinidae Silphidae Scarabaeoidea Chrysomelidae Cerambycidae Bruchidae Curculionidae Ehteridae Tenebrionidae Mordellidae Lagriidae Other beetles Hymenopteraa Diptera Lepidoptera Odonata Larva

Shilongmiao A1 A2 A3 – – –

Shihuimiao B1 B2 – 2

B3 –

B4 –

B5 –

Xinjiezhen C1 C2 C3 – – –

Hangjinqi D1 D2 – –

D3 –

D4 –

D5 –

D6 –

D7 1

D8 –

14 –

1 –

– –

– –

26 –

5 –

60 –

10 –

4 –

20 –

4 –

10 –

5 –

– –

30 –

10 –

34 1

51 4

– –

– – 9 – –

– – – – –

– – – – –

10 6 3 5 8

– – 3 30 –

– – 2 110 1

– – 730 – –

– – 3 – –

– – – – –

– – 1 – 1

– – 1 – 3

– 2 1 – –

18 6 1 5 –

– – – – –

– 1 1 7 –

– 2 – – –

– 4 – 39 –

– 1 – 19 –

– – – – –

– 2 – 1 1 – – – – – – 15 – – – 3 24 – – –

– 7 – – – – – – – – – 1 – – – 1 6 – 2 1

– 1 – 1 1 – – – – – – – – – – – – – – –

– 23 – – – 3 – – – 1 – 46 – – – 9 100 7 1 –

– 13 – – – – 27 – – 2 – 103 – – – 10 54 1 – –

– 33 – – – – – – – – – 125 – – – 49 35 43 – –

– 172 – – – – 1 – – – 1 – – – – 10 10 – 1 2

– 22 – – – – – – – 24 – – 1 3 1 9 46 5 – –

– 1 – – – – – – – – – 4 – – – 1 4 13 – –

– 5 – – – – – – – 1 – 7 – – 2 4 11 – – –

– – – – – – – – – 2 – 9 – – – 3 8 – – 1

– 1 – – – – – – – 6 – 51 – – – 56 110 16 – 1

– – – – – 9 – – – 7 – 65 – – – 19 150 4 – –

37 70 – – – 13 26 – – – – 66 – – – – – – – –

– 3 – – – – 3 – – – 1 80 – – – 212 40 11 – –

– 6 – – – 6 – – – 1 – 299 – – – 236 126 156 – 1

– 2 – – – – – 2 13 – – 327

– – – – – 2 – – 3 2 – 276 – – – 11 17 3 – 19

– – – – – – – – 2 1 – 320 – – – – – – – –

– – 26 50 24 – 1

a

Ants are not included. Abbreviations: A1 Sabina vulgaris shrub stand; A2 Salix psammophila shrub stand; A3 Hedysarum laeve shrub stand; B1 Caragana korshinskii shrub stand; B2 Artemisia ordosica shrub stand; B3 Stipa bungeana plus Thymus mongolicus steppe stand; B4 Carex duriuscula meadow stand; B5 Populus plantation; C1 Salix artificial stand; C2 Pine plantation; C3 Oxytropis shrub stand; D1 Achnatherum splendens meadow stand; D2 Nitraria tangutorum stand; D3 Artemisia ordosica stand; D4 Caragana tibetica shrub stand; D5 C. opulens stand; D6 Reaumuria soongorica stand; D7 Tetraena mongolica stand; D8 Ammopiptanthus mongolicus shrub stand. (After Yu et al. 2001)

of this area, insect species are rather diverse and abundant, being highly plant specific in their distribution and niche occupation. It was observed that, unlike for characteristic steppes, both legumes and grasses were eaten or occupied by most of the insects here. For example, Megaloceraea ruficornis and Psammotettix striatus, the most frequent and host-diverse species, infested nearly all major plant species, and Empoasca limpofera and E. flavescens fed specifically on legumes such as Astragalus spp., whereas Delphacidae species, notably Sogatella furcifera, Laodelphax striatella, and Unkanodes sapporona, fed mainly on annual grasses (He et al. 1988). In several sandy grassland communities distributed in a transitional ecotone between the Ordos sandland and the

Loess Plateau steppe regions, about 18 species of grasshoppers were documented, with Calliptamus abbreviatus, Chorthippus spp., Euchorthippus unicolor, Epacromius coerulipes, Oedaleus spp., Sphingonotus yenchihensis, S. mongolicus, Angaracris rhodopa, and A. barabensis as the common species (Liu 2003). The overall density of individuals averaged 1.39 ind./m2, ranging from 1.2 to 1.58 ind./m2 among the communities. By contrast, Liu et al. (2003) identified 12 grasshopper species occurring in four kinds of sandy vegetation in the southern Mu Us sandland, belonging to 10 genera and 5 families. Chorthippus albonemus, Ch. biguttulus, and Acrida cinerea were present in most of the communities; Oedaleus infernalis, Oxya adentata, Epacromius coerulipes,

12.5

Fauna

383

Table 12.17 Weekly variations in average density of grasshoppers in different habitats of the Horqin sandland (ind./m2) Habitat Hilly dry steppe Sand dune field Inter-dune meadow a

May 21a 3.2 0.1 3.9

28 2.3 2.8 5.7

June 4 2.8 5.3 7.2

11 4.8 8.3 12.0

17 6.9 4.6 16.2

24 9.0 9.0 48.0

July 2 34.2 9.5 67.0

9 29.6 6.0 66.0

17 23.4 11.9 46.4

23 25.2 10.0 49.1

30 16.5 8.0 34.4

Aug. 6 18.7 7.0 27.9

12 8.5 7.0 32.6

Date. (After Gao et al. 2007)

and Atractomorpha sinensis were most frequent in the Pennisetum flaccidum plus Artemisia frigida community; and Chorthippus spp., especially Ch. hsia, Omocestus haemorrhoidalis, and Calliptamus abbreviatus, were most abundant in two shrub communities. However, only one species, Chorthippus biguttulus, was found in the Artemisia sphaerocephala plus Psammochloa mongolica community. A field investigation in the northern Horqin sandland showed that Oedaleus decorus asiaticus, Myrmeleotettix spp., Calliptamus abbreviatus, and Chorthippus brunneus huabeiensis were the commonest grasshopper species in the sand dune steppe stands, while Euchorthippus vittatus and Epacromius coerulipes were most dominant in the inter-dune meadow stands (Table 12.17). In the Hulun Buir sandland, 120 insect species in 25 families and 6 orders are identified, the most prominent of which were Pararcyptera microptera meridionalis, Celes sp., Harpalus griseus, Cassida mongolica, and Cassida viridis. In addition, Pararcyptera microptera meridionalis, Mylabris calida, and M. pusilla are the major pests which most frequently feed on Agropyron, Agriophyllum squarrosum, and Corispermum hyssopifolium, with an infestation rate of 72% on average, whereas the important enemy insects are Chrysoperla sinica, Ch. carnea, and Deraeocoris ater (Bao and Wu 2002). Seven Hemipteran species were observed to live on Psammochloa villosa in the sandy grasslands of Inner Mongolia, including Stenodema virens, S. crassipes, S. deserta, Trigonotylus major, and T. pallescens (Liu et al. 1997). Most of the species in the family Carabidae (ground beetles) are beneficial organisms in sandy and desert grasslands. Morphologically, they commonly are shiny black and have ridged wing covers that are fused, rendering the beetles incapable of flying. Most of them are carnivorous and actively hunt for invertebrates, being famous for hunting caterpillars such as tussock moths and woolly worms, and sometimes earthworms. In the Yanchi desert rangeland of Ningxia, 15 species of ground beetles in 9 genera were observed, with Pterostichus gebleri, Pseudotaphoxenus mongolicus, P. brevipennis, and Harpalus salinus being most dominant in the various habitats. Common species include Amara dux, Calosoma maderae, Corsyra fusula, Cymindis binotata, C. daimio, Dolichus halensis, Harpalus

amplicollis, H. calceatus, H. crates, H. pallidipennis, and Scarites terricola (He et al. 2011). Zhang et al. (2012) asserted that darkling beetles can be used as indicator species for different habitats of the sandy or desert environments. For example, Anatolica potanini, A. mucronata, and Mantichorula semenowi were most indicative of the fixed sand dunes, while Trigonocnera pseudopimelia, Cyphogenia chinensis, and Anatolica nureti are indicators of the desert steppe. By contrast, three species of Microdera, i.e., M. kraatzi, M. kraatzi alashanica, and M. globata, are dominant throughout the sandy environments, thus being indicators for various shifting and semifixed sand dune fields. Liu et al. (2003) reported 11 Hemipteran species belonging to 8 genera and 5 families occurring in the Shapotou sandland. Of these, Aethus flavicornis, Lygus wagneri, and Jakowleffia setulosa were the most abundant, while Lygus rugulipennis, Lygaeus simulans, and Centrocoris volxemi were the common associates.

12.5.6 Soil Fauna In a Caragana- and Artemisia-dominated sandy community of the Horqin sandland, 47 groups of macrofauna were recognized, which belong to 38 families in 10 orders (Table 12.18). Staphylinidae and Formicidae were the most dominant taxa, which contained about 35% of the total abundance of individuals; 20 groups were common, while the remaining 25 groups were occasional (Liu and Zhu 2013). Correlations between community traits, abundance of certain macrofaunal groups and environmental factors are presented in Table 12.19. In a Horqin sandy grassland dominated by Artemisia halodendron and Caragana microphylla, more than 30 groups of macro-arthropods were identified. Anthicidae was most dominant in spring and summer, and Melolonthidae was dominant during the autumn. The overall density of macro-arthropods averaged about 125 ind./m2, varying from 70 ind./m2 in autumn to 180 ind./m2 in summer. Vertically, 0–10, 10–20, and 20–30 cm soil layers each contained 30, 27, and 11 groups/m2 and 38%, 41%, and 21% of the total abundance, respectively. With intensifying desertification, Tenebrionidae became increasingly

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12 Sandy Grassland Ecosystem

Table 12.18 Composition of macrofaunal groups and their seasonal variations in abundance in a Horqin sandland community Groups Acarina (o) (Mites) Scolopendromorpha Scolopendra subspinipes Araneida (o) Araneidae Linyphiidae Salticidae Callilopisnocturnae Thomisidae Philodromidae Oxyopidae Lycosidae Orthoptera (o) Gryllotalpidae Gryllidae Homoptera (o) Cicadellidae Hemiptera (o) Miridae Alydidae Coreoidea Rhopalidae Lygaeidae Cydnidae Pentatomidae Coleoptera (o) Carabidae Chrysomelidae Ehteridae Coccinellidae Staphylinidae Aphodiidae Melolonthidae Scarabaeoidea Pselaphidae Tenebrionidae Curculionidae Carabidae Meloidae Chrysomelidae larvae Elateridae Coccinellidae larvae Buprestidae Melolonthidae larvae Tenebrionidae larvae Curculionidae larvae Diptera (o) Aslidae Lepidoptera (o) Noctuidae Pyralididae Noctuidae Hymenoptera (o) Formicidae Tenthredinidae

Spring D 1.11  1.11

A ++

Summer D 2.22  2.22

A ++

Autumn D 0.00

A

Total D 6.67

A ++

0.56  0.56

++

1.11

+

1.11 4.44 2.22 15.56 17.78 6.67 10.00 1.11

+ + + ++ ++ ++ ++ +

1.11 3.33

+ +

5.56

+

11.11 2.22 6.67 7.78 12.22 7.78 1.11

++ + ++ ++ ++ ++ +

16.67 2.22 1.11 2.22 98.89 3.33 2.22 2.22 2.22 13.33 21.11 14.44 2.22 4.44 7.78 1.11 1.11 54.44 20.00 32.22

++ + + + +++ + + + + ++ ++ ++ + + ++ + + ++ ++ ++

0.00

0.00

0.00 0.00 0.00 5.56  3.33 3.33  3.33a 1.11  1.11 0.00 0.00

0.56  0.56 2.22  2.22 1.11  0.01 2.22  1.11 5.00  0.56a 2.22  0.02 3.33  2.22 0.56  0.56

+ ++ + ++ ++ ++ ++ +

0.00 0.00 0.00 0.00 0.56  0.56b 0.00 1.67  0.56 0.00

0.56  0.56 1.11  0.01

+ +

0.00 0.56  0.56

++ ++ ++

0.00 0.00

++ ++

++

1.11  1.11

++

1.67  0.56

++

0.00

1.11  1.11ab 1.11  1.11 3.33  1.11 1.11  1.11 3.33  1.11 1.11  1.11a 0.00

++ ++ ++ ++ ++ ++

3.89  0.56a 0.00 0.00 2.78  1.67 2.78  1.67 2.22  1.11a 0.56  0.56

++

0.56  0.56b 0.00 0.00 0.00 0.00 0.56  0.56b 0.00

1.11  1.11b 0.00 0.00 1.11  1.11 17.78  17.78 0.00 0.00 0.00 0.00 4.44  4.44 4.44  4.44a 6.67  4.44 0.00 2.22  0.02 3.33  1.11 0.00 0.00 6.67  6.67b 3.33  1.11a 14.44  5.56

++

6.67  4.44a 1.11  1.11 0.56  0.56 0.00 31.67  31.67 1.67  1.67 0.00 0.00 1.11  1.11 2.22  2.22 3.89  2.78a 0.56  0.56 1.11  1.11 0.00 0.56  0.56 0.56  0.56 0.56  0.56 16.67  15.56a 4.44  4.44a 1.67  0.56

+ + + +++ ++ ++

0.56  0.56b 0.00 0.00 0.00 0.00 0.00 1.11  1.11 1.11  1.11 0.00 0.00 2.22  2.22a 0.00 0.00 0.00 0.00 0.00 0.00 3.89  3.89b 2.22  2.22a 0.00

0.00

3.33  3.33

++

2.78  1.0.67

+++

12.22

++

0.00 0.00 0.00

0.56  0.56 3.89  3.89 2.22  1.11

+ ++ ++

0.00 2.22  0.04 0.00

++

1.11 12.22 4.44

+ ++ +

32.22  13.33a 0.56  0.56

+++ +

2.78  1.67b 0.00

96.67 1.11

+++ +

13.33  0.46ab 0.00

++ +++

++ ++ ++ ++ ++

++ ++ +++

+++

++ ++ ++ + ++ + + +++ ++

+ ++ ++ + +

Note: + rare; ++ common; +++ dominant; D density (ind./m2); A abundance. (After Liu and Zhu 2013)

++

++

++

++ ++

++

+++ ++

+++

12.5

Fauna

385

Table 12.19 Correlations between community traits, abundance of certain macrofaunal groups, and environmental factors in a Horqin sandland community Item Density Group number Shannon index Evenness index Salticidae Philodromidae Gryllidae Miridae Coreoidea Ch. larvae N. larvae Formicidae

Correlation coefficient SM ST 0.2614 0.7299 0.5086 0.7774* 0.2183 0.8894* 0.4523 0.8271* 0.8476* 0.6983 0.3827 0.7860 0.8159* 0.2016 0.6644 0.7053 0.8178* 0.2506 0.8834* 0.2707 0.7228 0.5956 0.5103 0.7645

R 0.7367 0.8059* 0.8885* 0.8493* 0.7601 0.8028* 0.2722 0.7500 0.1691 0.1827 0.6482 0.7936*

AT 0.7060 0.8531* 0.8163* 0.8686* 0.9381** 0.8048* 0.5218 0.8632* 0.1564 0.1690 0.7999* 0.8434*

Abbreviations: SM soil moisture; ST soil temperature; R rainfall; AT air temperature; Ch Chrysomelidae; N Noctuidae. *P < 0.05. (After Liu and Zhu 2013)

dominant, especially in spring and at the 10–20 cm soil layer, with Elateridae, Araneidae, Myrmeleontidae, and Labiduridae occurring in varying amounts. More noticeably, desertification had significant impacts on the group richness and individual abundances as well as the spatial and temporal patterns of soil arthropods, although in complicated manners (Table 12.20). In a sandland of the same region (Horqin), Zhang et al. (2009) revealed a total of 31 genera of Nematoda occurring in the various sandy habitats, with inter-dune sites and lower positions of leeward sand dunes containing the most genera (21), in sharp contrast to that on the windward side (6 genera) (Table 12.21). The abundance of nematodes also differed significantly among different soil depths (Fig. 12.5), with a vertical range of 0–60 cm in the soil and a decreasing trend with soil depth. In a Horqin sandy steppe composed of grasses, Artemisia spp. and Caragana microphylla, Liu et al. (2010) showed that different groups of arthropods differed in their responses to different grazing intensities (Table 12.22). Generally, grazing significantly reduced the abundance and number of

groups to varying extents at all grazing intensities. Soil pH value, bulk density, and vegetation traits were important factors in generating these effects. In the Hulun Buir sandland, Lü et al. (2007) showed that nematodes were the only dominant group of meso- and microfauna, while Coleoptera and Hemiptera were the dominant groups of macrofauna. The group richness and total abundance of soil fauna displayed an obvious decreasing trend with the aggravation of steppe desertification. The total abundance of soil fauna in the 0–20 cm soil layer had significant linear correlations with soil nutrient and moisture contents, soil pH value, and litter mass, separately. In the various sandy grassland stands of the Mu Us sandland dominated by Lespedeza potaninii, Artemisia ordosica, and grasses, 39 groups of soil fauna belonging to 11 orders, 4 classes, and 2 phyla were identified, of which Pygmephoridae, Onychiuridae, and Myrmicinae were dominant. Common groups included Nematoda, Protura, Hypogastruridae, and Homoptera. Vertically, about 40.3% of all individuals were aggregated in the 10–15 cm soil layer, with only 27.7% occurring in the 0–5 cm soil layer, in striking contrast to the Horqin sandland. Seasonally, peak abundance values occurred mostly in August. The relationship between the abundance of soil fauna and pH value was found to be most significant, while the group richness in this sandland was most significantly related to soil water content and plant species richness (Shi 2010). The effects of livestock grazing on soil faunal communities are complicated, group specific, and grazing intensity dependent. In a Horqin sandland, Liu et al. (2010) showed that dominant groups of soil animals differed in their responses to grazing (Table 12.23). For example, among the dominant groups, Scarabaeoidae adults did not change much in their dominance value, whereas Hemiptera, Elateridae, and Hymenoptera decreased significantly and linearly in their abundances with increasing grazing intensity. However, for most of the other groups, notably Carabidae, Scarabaeoidae larvae, Diptera, Formicidae, and Araneida, their respective abundances or frequencies were highest at light-to-moderate grazing intensities. The effects of grazing, especially at the heavy intensity, were substantial on the seasonal pattern of

Table 12.20 Changes in soil animal group richness and individual density in soil profile with increasing desertification in a Horqin sandy grassland Item GR

DI

D (cm) 0–10 10–20 20–30 0–10 10–20 20–30

NDS 30.0  5.0aA 27.0  3.5aA 17.0  3.0aA 67.8  19.2aA 73.3  40.8aA 38.8  39.4aB

LDS 11.0  3.0bA 10.0  1.0bA 17.0  3.0aA 67.8  19.2aA 73.3  40.8aA 38.8  39.4aB

MDS 15.0  1.0bA 8.0  3.0bB 4.0  1.0bC 41.6  3.2bA 22.4  3.2bB 6.4  3.2cC

HDS 7.0  2.0cA 4.0  1.0cA 6.0  2.0bA 27.2  3.2cA 8.0  4.8cC 6.4  3.2cC

EDS 4.0  0.0dA 1.0  0.0dB 5.0  2.0bA 8.0  1.6dA 3.2  1.6cA 8.0  4.8cA

Abbreviations: D soil depth; NDS non-desertified stand; LDS lightly desertified stand; MDS moderately desertified stand; HDS heavily desertified stand; EDS extremely desertified stand; GR group richness (no./m2); DI density of individuals (ind./m2). Different capital letters in the same column and lowercase letters in the same row indicate significant differences at P < 0.05 level. (Adapted from Zhao et al. 2013)

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12 Sandy Grassland Ecosystem

Table 12.21 Relative abundances of different nematode genera at different positions along sand dunes in a Horqin sandland Genera Acrobeloides Acrobeles Alaimus Cervidellus Chiloplacus Heterocephalobus Mesorhabditis Plectus Prismatolaimus Protorhabditis Teratocephalus Wilsonema Aphelenchus Aphelenchoides Tylencholaimellus Tylencholaimus Atylenchus Criconemoides Dorylaimellus Filenchus Geocenamus Helicotylenchus Hemicycliophora Heterodera Paratylenchus Paratrichodorus Pratylenchus Aporcelaimellus Discolaimus Epidorylaimus Microdorylaimus

ID 2.8 4.5 0.0 0.0 0.9 0.2 0.1 1.2 0.1 0.8 7.8 0.0 0.1 0.3 1.6 8.1 2.2 0.0 0.0 9.4 0.0 0.0 18.4 1.0 0.1 35.1 0.0 5.1 0.0 0.8 0.4

I 10.9 6.1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 9.1 0.0 16.7 4.8 0.0 0.0 0.0 0.0 0.0 0.0 2.4 0.0 0.0 25.7 0.0 9.1 0.0 3.0 0.0 0.0 0.0 12.1

Wm 10.4 26.1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 16.2 18.2 0.0 4.0 0.0 0.0 0.0 6.1 0.0 0.0 9.1 4.5 5.5 0.0 0.0 0.0 0.0 0.0 0.0

T 13.9 7.1 0.0 0.9 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 7.3 0.0 1.1 0.0 0.0 1.8 14.4 0.0 5.6 9.1 5.6 0.0 4.4 3.7 24.2 0.9 0.0 0.0

Lu 13.5 13.8 0.0 0.0 0.5 1.8 0.0 0.0 0.0 0.0 0.0 0.0 8.3 12.6 0.0 3.1 0.0 11.4 0.0 19.0 1.1 0.0 1.7 0.0 2.3 0.0 3.0 4.2 0.0 0.0 3.6

Ll 16.9 24.9 0.0 4.2 2.2 0.4 0.4 0.0 0.0 0.9 0.1 0.5 6.6 4.1 0.0 3.8 0.0 6.5 1.2 5.8 0.0 0.0 0.0 0.5 6.1 0.0 0.4 12.7 0.4 0.0 1.5

Abbreviations: ID inter-dune; I interface; Wm windward mid-sand dune; T top of sand dune; Lu leeward-side upper sand dune; Ll leeward-side lower sand dune. (After Zhang et al. 2009)

the abundances of some macrofaunal groups, such as of Scarabaeoidae, Carabidae, and Hemiptera, but not for others such as Formicidae and Diptera. As a result, grazing did not significantly affect the overall pattern of the soil-faunal community as a whole. By contrast, moderate-to-heavy grazing significantly modified the seasonal patterns of nematodes and mites. A similarity analysis showed that the community structure of soil fauna in the heavily grazed stand was significantly different from that of the less grazed or ungrazed stand. A survey of soil macrofaunal communities was conducted in various habitats of this sandland, including mobile, semimobile, semifixed, fixed, and inter-dune sites that represented the five stages of desertification (Liu and Zhao 2012). The results showed that the individual abundances, group richness, and diversity of the soil macrofaunal

Fig. 12.5 Variations in the abundance of total nematodes with sand dune position and soil depth in a Horqin sandland. (After Zhang et al. 2009)

community in the mobile sandland were all significantly lower than those in the other four habitats, and that no significant differences in these aspects were detected between one another of the latter four sites. In addition, the fixed sand field had an exceptionally higher soil faunal biomass than the other habitats (Fig. 12.6). Clearly, changes in soil organic carbon, pH status, and moisture were the principal factors determining the abundance and group richness of soil macrofauna in this sandland.

12.6

Microbes

12.6.1 Soil Microorganisms An investigation of five sandland sites conducted in Naiman area of the southern Horqin sandland indicated that bacteria were most abundant in the soils (Table 12.24). Afforestation had substantially enhanced the abundance of fungi and bacteria, but posed either no or occasionally negative effects on that of actinomycetes. In addition, both the abundances and activities of various organismal groups were fairly constant with respect to soil depth down to 40 cm of the same site, whereas they were rather variable with vegetation- and sitespecific conditions (Chen and Li 1992). Microbial biomass carbon (MBC) is generally less variable with vegetation type and soil depth in the soils of the Horqin sandlands. A study conducted within communities occurring in the western Horqin sandland (Ulanodo) dominated in turn by Caragana microphylla, Artemisia halodendron, Hedysarum fruticosum, and Pinus sylvestris var. mongolica showed that the maximum MBC contents were all between 300 and 350 mg/kg of dry soil and rather

12.6

Microbes

387

Table 12.22 Changes in the density of different groups of soil animals in response to varying grazing intensities (ind./m2) Animal group Araneida Scolopendromorpha Orthoptera Homoptera Hemiptera Coleoptera adult Coleoptera larva Diptera larvae Lepidoptera adult Lepidoptera larvae Hymenoptera Acarina Collembola Psocoptera

Treatment NG 23.33(0.45)

LG 5.56(0.22) 2.22(0.09)

2.22(0.04) 15.56(0.30) 77.78(1.51) 48.89(0.95) 7.78(0.15) 1.11(0.02) 11.11(0.22) 46.67(0.91) 2921.11(56.66) 1083.33(21.01) 916.67(17.78)

1.11(0.04) 7.78(0.31) 11.11(0.45) 7.78(0.31) 1.11(0.04) 1.11(0.04) 37.78(1.51) 1668.89(66.90) 166.67(6.68) 583.33(23.39)

MG 11.11(1.51)

HG 13.33(0.30)

1.11(0.15) 1.11(0.15) 11.11(1.51) 20.00(2.72) 3.33(0.45)

1.11(0.15) 18.89(2.57) 250.00(34.04) 416.67(56.73)

10.00(0.22) 24.44(0.54) 13.33(0.30) 5.56(0.12) 1.11(0.02) 34.44(0.76) 2333.33(51.64) 1083.33(23.97) 1000.00(22.13)

Abbreviations: no grazing; LG light grazing; MG moderate grazing; HG heavy grazing. Numbers in parentheses represent percentages in the total abundance of all groups. (Adapted from Liu et al. 2010)

Table 12.23 Variations in density (ind./m2, upper subrow) and biomass (g/m2, lower subrow) of dominant groups of soil animals with different grazing intensities in a Horqin sandland Group Macrofauna Scarabaeoidae Carabidae Formicidae Hemiptera Diptera Nematodaa Mitesa

Grazing intensity HG MG 24.0 53.6 1.028 1.000 6.4 12.0 0.684 0.572 4.4 7.6 0.200 0.156 2.0 16.8 0.004 0.012 0.4 3.6 0.004 0.048 2.8 4.4 0.308 0.060 7.9  104 1.7  105 356.7 764.3

LG 59.6 1.736 15.6 0.560 11.6 0.208 12.4 0.024 5.6 0.092 2.4 0.024 2.0  105 1273.9

CK 51.2 1.008 10.8 0.356 6.8 0.112 10.8 0.036 7.2 0.056 2.4 0.044 3.3  105 356.7

a

Only density values. Abbreviations: HG heavy grazing; MG moderate grazing; LG light grazing. (After Liu et al. 2010)

consistent along the 0–30 cm soil profile, but varied by twoto threefold during the growth season. The maximum MBN values varied between 20 and 30 mg/kg of dry soil, and no significant differences were detected among the communities, soil sub-layers, or months during summer (Cao et al. 2011a). There were significant increases in MBC and MBN contents in the 0–20 cm soil layer with increasing stand age in a Caragana microphylla sandland, whereas no significant variations in these aspects were found in the subsoil below the 20 cm soil depth (Teng et al. 2007; Cao et al. 2011b). The only available estimates of microbial

biomass were made in an Artemisia desertorum stand of this region; they were 12.80, 156.24, 110.86, and 279.90 gC/m2 for bacteria, fungi, actinomycetes, and total, respectively, for the 0–30 cm soil layer (Zhao et al. 1999). Wang et al. (2010) noted that soil microorganisms were more abundant in the subsoil than in the topsoil in sand dune fields. They also detected substantial inter-region variations in the abundance of soil microbes in communities with similar vegetal and ground conditions (Table 12.25).

12.6.2 Rhizospheric Microorganisms An investigation in the Horqin sandland showed that non-sporal bacteria were most numerous in the rhizosphere, accounting for 78.02–99.76% of the total amount of rhizospheric microorganisms associated with different plant species (Chen and Li 1987). Significant differences were detected in the abundances of overall microflora as well as their various types and major functional groups except for actinomycetes and nitrifying bacteria between rhizospheric and non-rhizospheric soils, all of which were rather consistent among the host plants. Additionally, significant differences in the absolute abundance of the total rhizospheric microflora, as well as of fungi, actinomycetes, and major functional groups, existed among the plant species. Of special note, most of the differences between rhizospheric and root-free soils appeared to become not significant with the aging of vegetation (e.g., 8-year-old vs. 25-year-old H. scoparium stands). In addition, the quantity of fungi and actinomycetes in root-free soils exceeded that of the rhizosphere. The commonest microbial species were Bacillus mesentericus (subtilis), B. megaterium, and B. idosus for

388

12 Sandy Grassland Ecosystem

Fig. 12.6 Variations in community traits of soil macrofauna with intensifying desertification in a Horqin sandland. LD, MD, HD, and SD denote light, moderate, heavy, and severe stages of desertification. (Adapted from Liu and Zhao 2012)

Table 12.24 Abundances of certain functional groups of soil microbes (0–40 cm soil layer) at different sites of a Horqin sandland Items Ammonifiers (106 ind.)b Azotobacter (103 ind.) Oligonitrophilic bacteria (103 ind.) Nitrite bacteria (103 ind.) Cellulose-decomposing bacteria (103 ind.) Silicate bacteria (103 ind.)

Sitesa 1 4.769 8.7 412 0.07 6.1 2.2

2 4.569 6.5 176 0.03 1.7 4.5

3 0.708 0.5 22 0.02 8.5 3.0

4 1.576 0.3 19 0.03 6.5 2.6

5 0.297 0.1 9.7 0.03 2.2 1.7

Note: a(1) Agriophyllum squarrosum community, (2) Artemisia halodendron community, (3) Salix gordejevii community, (4) Pinus sylvestris var. mongolica community, (5) mobile sand dune field; bper g dry soil. (Adapted from Chen and Li 1992)

Table 12.25 Comparison in the abundance and biomass contents of major microbial groups in two contrasting communities Community C. microphylla in Hunshan Daka C. microphylla in Horqinb

MAT (
C) 0–3

MAP (mm) 389.4

3–7

364.5

SD (cm) 0–10 10–20 0–10 10–20

pH 7.09 7.29 7.78 7.87

SOC (g/kg) 1.078 1.586 0.387 0.512

Bacteria (105/g) 5.7 6.9 4.0 4.4

Fungi (102/g) 1.8 2.5 0.7 0.8

Actinom. (105/g) 2.2 2.9 2.0 2.5

Biomass (mg/kg) 60 145 45 85

Note: aComposed of Artemisia frigida, A. intramongolica, Stipa krylovii, Thymus serpyllum, and Puccinellia tenuiflora, at 116
050 E, 43
070 N; b consisting of Caragana microphylla, Artemisia halodendron, Salsola collina, Pennisetum centrasiaticum, and Digitaria sanguinalis, at 120
550 E, 42
410 N. Abbreviations: C. microphylla Caragana microphylla; MAT mean annual temperature; MAP mean annual precipitation; SD soil depth; SOC soil organic carbon. (Adapted from Wang et al. 2010)

12.6

Microbes

389

Table 12.26 Abundances of rhizospheric microorganisms (ind./g dry soil) associated with roots of dominant plants in the Horqin sandland

Plant Hs

Ck

Ao

P Rhiz. RPSa Soilb Rhiz. RPS Soil Rhiz. RPS Soil

TMAc ( 107) 8.7238 0.479 0.6952 10.981 0.4823 0.3109 12.4853 0.2873 0.162

Bacteria ( 107) NSBd SBe 6.807 0.4271 0.2814 0.0118 0.6292 0.0008 10.7025 0.2588 0.4282 0.0044 0.3 0.0026 12.456 0.02 0.2706 0.0007 0.1531 0.0006

Fungi ( 104) 2.4343 0.5556 0.3845 0.2881 0.0612 0.056 0.0254 0.0051

Actin. ( 107) 1.4873 0.1852 0.0648 0.0194 0.0496 0.0082 0.0092 0.0159 0.0083

Amm. ( 107) 7.2341 0.2932 0.6299 10.9613 0.4326 0.3026 24.9413 0.5579 0.315

Nitr. ( 100) 5 22 0 3 36 4 28 18 5

CDB ( 104) 1.03 0.113 0.051 0.74 0.0315 0.051 0 0.041 0.0168

SM (%) 65 2.05 3.2 73 2.68 2.7 85 3.3 3.01

Avail. nutrients (g/kg) N P2O5 K2O 0.28 0.14

0.15 0.06

1.05 1.03

0.24 0.15

0.53 0.12

1 0.9

0.26 0.14

0.05 0.22

0.98 0.96

Note: aRoot-penetrated soil; bdevoid of roots; ctotal microbial abundance of microflora, including bacteria, fungi, and actinomycetes; dnon-sporal bacteria; esporal bacteria. Abbreviations: Hs Hedysarum scoparium; Ck Caragana korshinskii; Ao Artemisia ordosica; P position; Amm ammonifying bacteria; Nitr nitrifying bacteria; CDB cellulose-decomposing bacteria; SM soil moisture. (Adapted from Chen and Li 1987)

bacteria, and Penicillium and Aspergillus for fungal species (Table 12.26) (Chen and Li 1987). In contrast, in the Mu Us and adjacent sandlands, Dai and Zaho (2011) showed that the abundance of microflora in rootpenetrated topsoils ranged from 9.3496 to 42.4141  108 for bacteria, from 1.3821 to 5.2794  106 for actinomycetes, and from 0.2034 to 8.5322  104 cfu/g of dry soil for fungi. In a Ningxia sandland, Zhang (2017) showed that the contents of total soil MBC ranged from 393.18 mg/kg of top soil (0–5 cm) down to about 170 mg/kg of subsoil (5–15 cm) in an Artemisia ordosica community, and from 221.71 mg/kg to about 70 mg/kg in a Caragana korshinskii community. Total soil MBC was rather horizontally heterogeneous on the ground within both communities. This is because that the MBC content in the soil near plants was one- to twofold higher than that in the bulk soil devoid of roots. Pu et al. (2015) reported that measured contents of MBC in the topsoils of three communities located in the southern Mu Us sandland were 288.35 mg/kg for the Hippophae rhamnoides plus Caragana microphylla stand, 196.73 mg/ kg for the Artemisia desertorum + Agriophyllum squarrosum community, and 235.67 mg/kg for the elm woodland. In a Qubuqi sandland, a separate study by Shao et al. (1996) in an Artemisia ordosica community revealed that the commonest microbial taxa present in the rhizosphere were tens of species of spore-bearing and sporeless bacteria; yellow, golden yellow, and ash-colored actinomycetes; and fungal genera Aspergillus, Penicillium, Stemphylium, Fusarium, Chaetornium, Mucor, Tricoderma, and Alternaria. The ratio of rhizospheric to non-rhizospheric sporeless bacteria varied between 1.04 and 2.81 in the topsoil and from 1.53 to 7.28 in the subsoil in different seasons, and the average absolute density of sporeless bacteria through the entire study period was 4–9  107 ind./g dry soil in the rhizosphere and 1–3  107 ind./g dry soil in the non-rhizosphere; by

contrast, this ratio for spore-bearing bacteria was more than 2.0 in most cases, irrespective of soil depth and sampling season. However, ratios less than 1.0 were observed in spring. In addition, the abundance of spore-bearing bacteria amounted to 1.76–4.47% of that of sporeless bacteria in the soil, regardless of space and time. The density of actinomycetes was generally 5–70  104 cfu per gram of dry soil, and the enrichment effects in the rhizosphere were less significant. By contrast, the enrichment effects for fungi were most significant and consistent, the R/S ratio of which averaged 5.8 in this community, with a range from 0.94 to 13.1. According to Tang (2016), the commonest bacterial taxa in the Hunshan Dak sandland soils are Rubrobacter, Microcoleus, Marmoricola, Actinoplanes, Blastocatella, Micromonosporaceae, and Pseudonocardia, along with other 30 odd occasional genera; prominent anoxygenic phototrophic bacteria are comprised of the genera Bradyrhizobium, Brevundimonas, Methylobacterium, Rhodospirillum, Roseiflexus, and Sphingomonas; important nitrogen-fixing bacteria include Alicycliphilus, Nostoc, and Cyanothece. By contrast, the dominant bacteria present in the rhizosphere of various sandy plants are generally Rhizobiales and Sphingomonadales during summer and Pseudomonas in the nongrowth seasons (Liu 2010). In the same sandland, Li et al. (2010) identified the following genera as the most dominant cellulose-degrading microbial taxa in topsoils near the roots of Caragana sinica and Nitraria tangutorum: Bacillus, Streptomyces, and Brevundimonas in bacteria, and Penicillium, Eupenicillium, and Mucor in fungi. The abundance of total bacteria typically peaked in the spring and bottomed out in autumn, while the opposite seasonal trajectory was true for cellulose-degrading bacteria, which peaked in the transitional period from summer to autumn but was lowest in spring (Table 12.27).

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Table 12.27 Abundances of bacterial and fungal taxa in soils near plant roots and in BSCs Soils BSCs Soil with Cs Soil with Nt

Bacteria (106/g d s) TB 9.111/0.425–30.5 3.793/0.523–8.35 3.705/0.650–8.05

CB 0.034/0.003–0.103 0.014/0.003–0.028 0.051/0.002–0.116

Fungi (104/g d s) TF (mean/range) 0.905/0.152–2.70 1.716/0.245–3.24 2.478/0.182–4.10

CF (mean/range) 0.438/0.013–1.63 0.436/0.038–1.10 0.364/0.034–0.970

Abbreviations: BSCs biological soil crusts; Cs Caragana sinica; Nt Nitraria tangutorum; TB total bacteria, seasonal mean/range; CB cellulosedegrading bacteria, seasonal mean/range; TF total fungi; CF cellulose-degrading fungi. (Adapted from Li 2010)

12.6.3 Microbiotic Crusts In the Horqin sandland, soil crusts generally consist of two organismal types, i.e., algae and bryophytes (mosses). In a field survey conducted by Ning et al. (2009), only two species of mosses were recognized, i.e., Bryum argenteum and B. caespiticium, with coverage varying between 1 and 8% in the various stands of a succession sere of vegetation dominated by Caragana microphylla and Artemisia halodendron. In a sandland dominated by Pennisetum centrasiaticum and Aristida adscensionis, Bryum argenteum was most abundant and frequent, with a standing crop biomass that averaged 2.08 g/m2 and ranged from 0.37 g/m2 in a heavily grazed stand to 3.92 g/m2 in a lightly grazed stand; the mean coverage was about 4.7%, ranging from 1.26 to 8.33% (Xü and Ning 2010). By contrast, algae are much more species rich and abundant. A total of 23 algal species were recognized in the soil crusts of a variety of habitats in the Horqin sandland, comprising 15 species of blue algae and 8 species of green algae (Xü et al. 2010). For the blue algae, the commonest species occurring on mobile sand dunes were Synechocystis crassa, S. aquatilis, Chroococcus minor, and Scytonema tenue; Microcoleus vaginatus, Anabaena azotica, Nostoc spp., and Microcystis densa were found mainly on fixed and semifixed sand dunes, whereas Gloeocapsa arenaria, G. aeruginosa, G. atrata, Scytonema incrassatum, and Borzia saxicola occurred only on moss crusts. In contrast, the most widespread green algae were Chlorella vulgaris and Chlorococcum humicola, while Pediastrum boryanum, Characium angustum, Actinotaenium cruciferum, and Chlamydomonas spp. occurred mainly on fixed sand dunes (Xü et al. 2010). These species usually form an algal crust layer that was 3–21% in cover at various sites (Ning et al. 2009). There were substantial inter-habitat and seasonal variations in species composition and abundance of algal communities in this sandland. Estimated values of algal biomass ranged from 3.648 μg chlorophyll a/cm2 in winter to 9.489 μg/cm2 in summer on fixed sand dunes, and from 1.958 to 8.674 μg chlorophyll a/cm2 correspondingly on semifixed sand dunes, which were assumed to be closely related to seasonal changes in both precipitation and temperature (Xü et al. 2010).

Xü and Ning (2010) reported that the algae in this region consisted mainly of Microcoleus vaginatus, Synechocystis pevalekii, Nostoc spp., Chlorella vulgaris, and Chlorococcum humicola. In a sandy grassland, the total standing crop biomass averaged 13.79 g/m2, ranging from 1.51 g/m2 in a heavily grazed stand to 29.03 g/m2 in a fenced stand; the mean coverage was about 11.09%, ranging from 3.23% to 20.90% among the stands. Cong et al. (2010) revealed that the majority of bacteria in biological soil crusts (BSCs) were affiliated to α- and γ-proteobacteria in the Hunshan Dak sandland. Dominant bacterial taxa were Pseudomonadaceae and Acinetobacter of γ-proteobacteria, which accounted for 14.5 and 18.2% of the total bacterial clones, respectively, while Sphingomonas of α-proteobacteria accounted for 12.7%. However, the common dominant bacteria in well-developed BSCs, notably Cyanobacteria, made up only 1.8% of the total clones. In addition, Chryseomonas, a nitrogen-fixing genus, and Rubellimicrobium, a genus capable of carrying on photosynthesis, were also found in BSCs in this sandland.

12.7

Succession

12.7.1 Hulun Buir Sandy Grassland In the Hulun Buir sandy grassland, the vegetationestablishing succession generally occurs in three stages. During the first stage, which is characterized by the mobile sand dune environment, annual plants, such as Agriophyllum squarrosum and Corispermum stauntonii, are most dominant within the community. During the second stage, certain species of sand-stress withstanding, perennial, xerophilous herbs (e.g., Cleistogenes squarrosa and Artemisia frigida) occupy the semifixed sand dunes formed during the first stage, with annual grasses Setaria viridis and Eragrostis minor and annual forbs Allium spp. and Saussurea runcinata as common associates. During the third stage when the sand dunes have become fixed, the transitional vegetation is partially dominated by Agropyron cristatum and C. squarrosa, while a greater area is dominated by Kochia prostrata, with Potentilla spp. the subdominant species. Grasses such as those of Agropyron, Poa, Stipa, and Cleistogenes rise and fall one

12.7

Succession

391

Table 12.28 Changes in soil properties with increasing enclosure time of a Hulun Buir sandy grassland T UE E1 E5 E10

TN 30 421 217 391

AK 26 46 67 94

Ca 4.97 8.54 5.95 1.84

AP 1.19 1.81 2.22 3.46

pH 7.36 6.81 6.80 6.77

EC 0.18 0.28 0.28 0.27

SOM 0.31 1.12 0.31 0.48

Abbreviations: T treatment; UE unenclosed; E1, 5, 10 enclosed for 1, 5, and 10 years, respectively; TN total nitrogen (g/kg); AK available K (g/kg); Ca calcium (g/kg); AP available P (mg kg1); EC electric conductance (ms cm1); SOM soil organic matter (%)

after another. The relevant changes in soil properties and community traits that occur during this process are summarized in Tables 12.28 and 12.29, respectively. In a sandy grassland of this region, Piao et al. (2008) observed that species richness increased from 2 species at the mobile site to 8 species at the semifixed sand dune field up to 31 species on the fixed sand dune field. In addition, the contents of soil nutrients also increased significantly with increasing restoration time. In a sandy steppe of Hulun Buir, Zhao et al. (2011) showed that the vegetal coverage, height, root and canopy biomass, and accumulated litter amount all decreased significantly with the development of desertification (Table 12.30). They noted that these traits were most sensitive to the stages of desertification, while changes in species richness and diversity of plants in response to desertification were both slow and time lagged. The same authors examined the effects of different stocking rates and enclosure on sandy grassland vegetation and found that only continuous long-term overgrazing resulted in serious vegetal degradation. Generally, grazing imposed the most pronounced impacts on the canopy and root biomass, while it had less significant effects on the species richness and diversity. They also found that moderate grazing basically had no noticeably harmful effects on major aspects of the community (Fig. 12.7). In addition, the restoration process was highly dependent on the site-specific climatic factors of this region (Zhao et al. 2009).

12.7.2 Horqin Sandy Grassland In the Horqin sandy grassland, Artemisia halodendron is often among the first species to invade mobile sand dunes at denuded sites, whereas Caragana microphylla usually occupies semifixed sand dune fields. With stabilization of the mobile sand dunes, A. halodendron gradually retreats from the community. By contrast, Salix gordejevii occurs primarily on the lowland between sand dunes. Huang et al. (2012) found that the mean values of the standing live and

dead fine-root biomass in the A. halodendron community were significantly lower than those of the two other stands. However, the turnover rate of fine roots was significantly faster in the A. halodendron stands than in the S. gordejevii and C. microphylla stands (Table 12.31). Artemisia halodendron is of special significance in the succession of sandland vegetation. This species is disconnectedly distributed mainly throughout the Horqin and Hulun Buir sandlands. As discussed previously, Agriophyllum squarrosum is often the sole species colonizing the mobile sand dune field. With progressive succession, the species richness increases significantly, becoming as diverse as 25 species at the climax stage, during which the Caragana microphylla–A. halodendron + A. frigida community comes into being and becomes stably established. In effect, A. halodendron is most favored by semimobile sand conditions, although it is also found on the leeward side of mobile sand dunes and fixed sandy sites. As a hemi-shrub, the species has rather soft small twigs that lie prostrate on the ground. When buried by sands or where soil moisture is adequate, the twigs may extend rapidly, a process by which the population can become rather competitive in its occupation of the habitat. However, when dune sands become stabilized, wind erosion and sand burial are significantly weakened and the species is no longer suited to develop under these conditions. Secondly, with the succession of the community, soil water becomes gradually deficient, a condition of which A. halodendron is also less tolerant. Additionally, soil biotic crusts and litter layers usually begin appearing on the soil surface at the late successional stage, further weakening the mobility of surface sands. Thus, its dominance value declines rapidly, even retreating completely from certain communities such as those dominated by Hedysarum fruticosum var. lignosum and Ceratoides arborescens (Li 1991). Ren (1990) asserted that the Artemisia halodendron + Lespedeza bicolor + Digitaria ischaemum community is most characteristic of the A. halodendron sandy grassland. Its herbage yield compares favorably with other sagebrush pastures, while its coverage may attain 30% or higher under moderate grazing. However, this community is also apt to be damaged or even extirpated by overgrazing and breaks down rapidly, with significant declines in biomass and coverage. The Naiman sandland lies in the southern portion of the Horqin sandland. About 90.7% of the useable pastures of this kind had become degraded as of the 1990s, of which about one-quarter was seriously damaged. In well-protected sites, Ulmus pumila, Caragana microphylla, Artemisia halodendron, and A. gmelinii are the most abundant species on fixed sand dune fields. Dominant at semifixed and active sand dunes are Salix gordejevii and Hedysarum fruticosum (Hou 1992). S. gordejevii, a pioneering perennial shrub, is an

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Table 12.29 Change in species composition and vegetal traits with increasing enclosure time of a Hulun Buir sandy grassland ET E0 E1

E5

E10

E18

Species Agriophyllum squarrosum Corispermum stauntonii Setaria viridis Agriophyllum squarrosum Corispermum stauntonii Thermopsis lanceolata Polygonum sibiricum Agropyron cristatum Cleistogenes squarrosa Saussurea runcinata Astragalus membranaceus Agriophyllum squarrosum Setaria viridis Corispermum stauntonii Leymus chinensis Chenopodium acuminatum Kochia scoparia Potentilla chinensis Setaria viridis Potentilla chinensis Polygonum sibiricum Kochia scoparia Leymus chinensis Artemisia halodendron Cleistogenes squarrosa Poa sphondylodes Allium bidentatum Geranium sibiricum Erodium stephanianum Saussurea salsa Caragana microphylla Agropyron cristatum Chenopodium album Agriophyllum squarrosum Corispermum stauntonii Artemisia frigida Artemisia frigida Leymus chinensis Agropyron cristatum Stipa grandis Allium bidentatum Salsola collina Potentilla bifurca Caragana microphylla Potentilla acaulis Cleistogenes squarrosa Chenopodium acuminatum Chenopodium album Polygonum sibiricum Phragmites communis Poa sphondylodes Taraxacum ohwianum Hedysarum fruticosum

RD 58.333 41.667 4.348 76.087 10.870 8.696 1.932 19.231 28.846 9.615 3.846 5.769 3.846 5.769 3.846 3.846 5.769 7.692 15.385 3.846 19.231 2.564 8.974 6.410 15.385 2.564 1.282 1.282 2.564 2.564 1.282 10.256 3.846 1.282 1.282 3.704 25.000 17.308 7.692 2.885 0.962 3.846 2.885 4.808 2.885 4.808 1.923 2.885 4.808 1.923 0.962 0.962 4.808

RF 59.988 40.012 19.422 43.159 28.787 8.632 2.941 20.588 26.471 8.824 5.882 5.882 4.412 5.882 4.412 2.941 5.882 5.882 13.208 1.887 10.377 1.887 9.434 8.491 16.981 5.660 3.774 3.774 2.830 3.774 2.830 9.434 1.887 1.887 1.887 3.636 15.534 9.709 9.709 3.883 1.942 5.825 5.825 7.767 5.825 3.883 3.883 3.883 1.942 3.883 1.942 1.942 2.913

RI 0.594 0.406 0.099 0.589 0.183 0.128 0.021 0.194 0.294 0.079 0.041 0.048 0.036 0.052 0.063 0.031 0.061 0.080 0.154 0.039 0.115 0.038 0.110 0.053 0.160 0.044 0.020 0.020 0.025 0.028 0.017 0.121 0.026 0.014 0.017 0.049 0.208 0.181 0.111 0.039 0.013 0.040 0.042 0.045 0.037 42.000 0.024 0.026 0.026 0.026 0.014 0.013 0.027 (continued)

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Table 12.29 (continued) ET

Species Lespedeza floribunda Kochia scoparia Glaux maritima Pseudolysimachion linariifolium subsp. dilatatum Thalictrum squarrosum Thermopsis lanceolata Asparagus dauricus

RD 1.923 1.923 0.962 0.962 0.962 0.962 0.962

RF 1.942 1.942 0.971 0.971 1.942 0.971 0.971

RI 0.019 0.021 0.010 0.010 0.011 0.008 0.008

Abbreviations: ET enclosure time; E0, 1, 5. . . enclosed for 0, 1, 5 . . . years; RD relative density (%); RF relative frequency; RI relative importance value (%)

Table 12.30 Changes in canopy and root biomass with intensifying desertification in a Hulun Buir sandy steppe S F SF SS Sh

CB 89.5  8.1a 66.4  13.4b 40.3  19.6c 1.4  1.3d

RB0~10 146.9  84.4a 62.4  23.2b 54.8  39.5b 2.8  3.1c

RB10~20 55.2  15.9a 36.5  17.3b 7.2  5.3c 0.9  0.6d

RB20~30 43.3  20.5a 16.1  2.7b 1.3  2.5c 0.5  0.3d

TRB 245.3  56.7a 115.0  23.2b 63.2  29.3c 4.2  1.2d

R/C 2.74 1.73 1.57 3.00

Abbreviations: S stage; F fixed sandy land; SF semifixed sandy land; SS semi-shifting sand dune field; Sh shifting sand dune field; CB canopy biomass (g m2); RB0~10 root biomass (g m2) in the 0–10 cm soil layer; TRB total root biomass (g m2); R/C root-to-canopy biomass ratio. (Adapted from Zhao et al. 2011)

indicator of the most seriously degraded habitat. A number of studies have concluded that the capable vegetative propagation of this species is the most principal trait for its success in dominating the community on the active sand dune sites (Liang et al. 2000; Ren et al. 2001; Yan et al. 2007).

12.7.3 Hunshan Dak sandland In the Hunshan Dak sandland, restoration succession on mobile and semifixed sand dunes is characterized by three phases: (1) the initial stage, at which the vegetation is usually dominated by Agriophyllum pungens and Corispermum heptapotamicum; (2) the middle stage, when Salix gordejevii, Artemisia intramongolica, and Cleistogenes squarrosa are most prominent; and (3) the late stage, during which Ulmus pumila var. sabulosa and Leymus secalinus become dominant (Fig. 12.8) (Liu et al. 2004). Of special note is that four out of the five species mentioned for the first two stages are C4 plants. On the mobile sand dunes further northward in this sandland, Agropyron desertorum is very common in the community; on semifixed sand dunes, Hedysarum fruticosum is the most prominent shrub, with Artemisia scoparia, Koeleria cristata, Allium anisopodium, and Thalictrum squarrosum springing up at different positions; on fixed sand dunes, Festuca dahurica and Poa attenuata are most dominant (Liu et al. 2005).

12.7.4 Mu Us Sandland In the Mu Us sandland, Guo (2000) described and depicted the autogenic successional sere of the sandy vegetation, consisting of, in progressive order, the barren sand dunes, the Artemisia sphaerocephala stand on semimobile sand dunes, the A. ordosica + sphaerocephala stand on semifixed sand dunes, the A. ordosica stand on fixed sand dunes, and finally the A. ordosica + Stipa bungeana + moss stand on old fixed sand dunes. Given adequate time, the sere will arrive at its zonal climax, i.e., the Stipa bungeana steppe. However, this so-called climax cannot be maintained for long, because S. bungeana is not at all resistant to sand burial and is also not very drought tolerant, and thus is likely to break down in such sandy environments even under slight disturbances. Thus, the optimal strategy for environmental benefits is to maintain the successional series at the prior stage, when the vegetation is both more stable and ecologically instrumental in conserving soil and water resources. To arrive at this end, moderate grazing is recommended (Guo 2000). Soil water is critical to plant growth and maintaining community sustainability in sandy areas. In the Mu Us sandland, precipitation is often the sole source of soil water, whereas water losses occur via several pathways, including physical evaporation, transpiration by plants, and percolation into deeper soil layers. Wang (1993) revealed that the soil water content was highest at the biological crust-covered, fixed sandy sites, which was related to the high water-

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Fig. 12.7 Changes in phytomass and plant species richness in response to long-term grazing of varying intensity in a Hulun Buir sandy steppe

holding capacity of the soil caused by well-established vegetation leading to significant improvements in soil organic matter and texture on these sites. However, it is from this stage on that the coverage and biomass of plants

began to decline and vegetative transpiration also correspondingly decreased. Yu et al. (2015b) noted that the succession of the A. ordosica community is a combined result of both abiotic

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Table 12.31 Standing crop biomass (g m2) and turnover rates (times per annum) of fine roots (1 mm) in three contrasting shrub stands of a Horqin sandland Item LFR

DFR

TOR

SD 0–20 20–40 0–40 0–20 20–40 0–40 0–20 20–40 0–40

Stands A. halodendron 41.60  3.82a 23.56  8.09a 64.24  8.98a 22.19  3.49a 14.67  3.16a 35.99  5.17a 1.94  0.18a 2.35  0.52a 2.12  0.23a

C. microphylla 48.37  8.02a 35.14  6.55a 82.42  10.36a 25.84  3.67a 23.27  2.76a 48.97  4.56b 1.38  0.52b 1.72  0.45b 1.55  0.44b

S. gordejevii 67.64  3.84b 43.45  3.47b 110.9  4.96b 30.04  5.52a 20.86  3.21a 50.78  6.48b 1.26  0.27b 1.32  0.27c 1.28  0.23b

Abbreviations: SD soil depth (cm); LFR live fine roots; DFR dead fine roots; TOR turnover rate. Values with different lowercase letters in the same subrow are significantly different at the P < 0.05 level. (After Huang et al. 2012)

and biotic elements, of which its competition with herbs both aboveground and belowground, the development of biological crusts, and the vertical distribution pattern of soil moisture are the particularly important aspects. Their study showed that with the progressive succession of the A. ordosica community, the species richness, herbaceous coverage and phytomass, and total community coverage all increased gradually, while the abundance, coverage, and leaf biomass of A. ordosica individuals, as well as the coverage of biological crusts, increased initially and then decreased (Table 12.32). The root distribution tended to concentrate towards deeper soil layers, of which the roots of herbs gradually dominated the 0–10 cm soil layer, with the proportion of A. ordosica’s fine roots in the 0–40 cm soil layer decreasing from 75.69% to 42.34% in total root biomass. In effect, the succession of vegetation in this sandland is largely dependent on the species composition and abundance of the seed bank. Yu et al. (2015a) showed that the species composition and proportional abundances of soil-stored seeds differed significantly among the different successional stages of the Artemisia ordosica sandland (Table 12.33). The similarity index was basically less than 50% between each of the stands. Generally, fixed sand dunes had the highest seed density (2276 seeds/m2), a bit higher than semifixed sand dunes (2099 seeds/m2), while significantly more numerous than the mobile sand dunes (1184 seeds/m2). The species composition and abundance were highly consistent between the canopy vegetation and the soil seed bank of the same stage. In addition, no apparent differences in the vertical distribution patterns of seeds were found among soils of different stages. Soil substrata also substantially influence the succession of the A. ordosica sandy grassland. A progressive

successional sere was recognized by Wang et al. (2007) following the order: the mobile sand dune field, the A. ordosica stand on semifixed sand dunes, the A. frigida stand on fixed sand dunes, the Ceratoides arborescens stand at inter-dune sites, and the Oxytropis aciphylla stand on the hard sandy ridge. The contents of soil organic matter and total nitrogen increased significantly with the restoration of vegetation (Fig. 12.9). Of special interest, the overall CaCO3 content also increased to an apparent degree, particularly that in the subsoil layer, meaning that biological accumulation played an increasingly forceful role in the dynamics of chemical matters in this sandland (Table 12.34). In the Gonghe sandy rangeland of Qinghai Province, the autogenically progressive successional pathway in vegetation follows the order: the Artemisia sphaerocephala stand on semi-drifting sand dunes ! the A. ordosica + A. sphaerocephala stand on semifixed sand dunes ! the A. ordosica stand on initially fixed sand dunes ! the A. ordosica + Stipa breviflora community on the stably fixed sand dune field. Moderate grazing on the fixed sand dunes is proposed as a managerial tool to maintain the stability of the A. ordosica sandland and arrest further vegetative succession (Song 2011), which is based on the same mechanism as previously discussed. In a sandy grassland distributed in the Yarlung Zangbo River valleys of Tibet, Li and Zhao (1994) recognized the progressive succession series starting from the mobile sand dune field as the sparse Agriophyllum spp. + Oxytropis spp. stand at the sand-shifting site, the Pennisetum flaccidum stand at the semi-shifting sandy site, the Artemisia wellbyi + Pennisetum flaccidum stand at the semifixed sandy site, the Sophora morcrot + Artemisia wellbyi stand at the fixed sandy site, the Sophora morcrot + Ajania myriantha + Ephedra saxatilis stand at the long-term fixed site. Subtropical lakeside sandlands occur mainly around large lake basins or alongside rivers, such as Poyang Lake, Dongting Lake, and the Yangtze River. In a sandland located in Jiangxi, Hu (2001) revealed that succession on the barren sandland consists of four stages. On the mobile sand field, mosses, lichen, algae, and a few annual herbaceous species such as Bulbostylis spp. are the first to appear; dominant at semimobile sandy sites are Digitaria spp., accompanied by annual grasses Eragrostis spp. and Setaria spp.; at the semifixed stage, Polygonum jucundum becomes dominant, with annual or biennial forbs increasing significantly and joining the previous annual grasses as important associates. At fixed sites, Eremochloa ophiuroides and Carex pumila become dominant. Given enough time, the community would develop towards a perennial grass-dominated tussock grassland. The Chinese coastline spans the temperate, subtropical, and tropical zones, with coastal sandlands occurring mainly

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Fig. 12.8 Dynamics of community traits at different stages of a regenerative succession sere with 18 years of restoration. (After Liu et al. 2004)

Table 12.32 Character values of Artemisia ordosica community at different successional stages (progressively from I to III) Items Number of species Coverage of A. ordosica (%) Biomass of A. ordosica (g m2) Herb coverage (%) Herb biomass (g m2) Total coverage (%) Biotic crust coverage (%) After Yu et al. (2015b)

I 5 32.25  1.61 17.58  0.88 10.54  0.53 14.23  0.71 42.79  2.14 0.14  0.01

II 12 37.2  1.86 38.85  1.94 12.57  0.63 16.93  0.85 49.77  2.49 35.57  1.78

III 22 3.620.18 3.21  0.16 60.82  3.04 61.26  3.06 64.44  3.22 2.08  0.10

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Table 12.33 Density and species composition of soil seed bank in stands at different successional stages of the Artemisia ordosica sandland Species Dysphania aristata Chenopodium acuminatum Bassia dasyphylla Corispermum chinganicum Agriophyllum squarrosum Salsola tragus Pugionium cornutum Astragalus melilotoides Lespedeza daurica Parthenocissus tricuspidata Hibiscus trionum Convolvulus arvensis Dracocephalum moldavica Artemisia sieversiana A. anethoides A. blepharolepis A. ordosica A. blepharolepis A. scoparia Ixeris chinensis Eragrostis minor Setaria viridis

Life-form Ah Ah Ah Ah Ah Ah Ph Ph S Ah Ah Ph Ah Ph Ph S S Ah Ph Ph Ah Ah

Soil seed bank density(ind./m2) Fixed Semimobile 463.70  139.85 32.59  1.81 102.22  43.32 0 0 35.56  23.38 12.09  4.68 68.14  18.23 0 7.40  2.96 0 1.48  1.48 0 69.62  33.51 0 23.70  12.51 0 4.44  2.96 23.70  10.05 5.92  3.79 0 0 0 2.96  2.96 2.96  2.96 0 47.40  44.44 0 2.96  2.96 0 0 1.48  1.48 41.48  11.38 7.40  1.81 1.48  1.48 82.96  23.82 1.48  1.48 0 35.55  10.21 14.81  5.88 471.11  110.50 0 1072.59  156.53 1718.52  483.35

Mobile 1.48  1.48 0 1.48  1.48 40.00  19.79 26.66  5.74 0 8.89  3.76 4.44  4.44 0 0 1.48  1.48 1.48  1.48 0 0 0 0 1.48  1.48 133.33  24.16 0 23.70  10.05 0 954.07  341.11

Abbreviations: S shrub and semishrub; Ah annual herb; Ph perennial herb. (After Yu et al. 2015a)

Fig. 12.9 Contents of certain chemical substances in soils with the Artemisia ordosica successional sere. (After Wang et al. 2007)

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Table 12.34 Variations in abundances of bacteria and actinomycetes and activity of dehydrogenase in soils with the Artemisia ordosica sere Item Bacteria (105/g)

Actinom. (105/g)

D activity (μgTTF g1 h1)

SD 0–5 5–20 20–40 0–5 5–20 20–40 0–5 5–20 20–40

M 2.6 3.43 3.03 0.1 0.05 0.03 1.64 0.64 0.16

SF 9.30  0.90a 6.48  1.45a 1.56  0.36b 1.92  0.71a 1.07  0.14a 0.73  0.24a 4.68  0.93ab 1.34  0.07b 1.23  0.36b

Ao 34.45  1.24c 8.51  0.91ab 6.43  1.81abd 1.79  0.74ab 1.84  0.22bc 0.99  0.44abc 6.12  0.64a 1.76  0.15bc 1.18  0.01bc

Af 18.54  7.30ad 9.5  0.23a 11.52  2.52a 2.22  0.81ac 1.26  0.16ac 2.67  0.75c 2.62  1.09b 1.37  0.20b 1.02  0.13b

Oa 65.67 43.33 6.50 2.18 1.74 1.31 2.84 1.99 1.19

Abbreviations: SD soil depth (cm); M mobile sand dunes; SF semifixed sand dunes; Ao Artemisia ordosica stand; Af Artemisia frigida stand; Oa Oxytropis aciphylla. (After Wang et al. 2007)

in three regions, i.e., the Shandong Peninsula, the Liaodong Peninsula, and the South China coastal areas (Zhao et al. 2014). Sandy landforms differ greatly with the distance from the sea. Away from the sea, foredunes, dune crests, and back dunes occur in sequence. Sandy beaches are the sites affected most intensely by the interactions between the land and sea environments, wherein plants are subjected to frequent salt sprays, sand burials, and erosions. Thus, they are usually low in stature and have thick and robust stems and twigs, such as Messerschmidia sibirica, Limonium bicolor, and Scorzonera mongolica. Some of them grow prostrately, with extensively creeping twigs, such as Zoysia macrostachya, Cayratia japonica, Asparagus cochinchinensis, Carex kobomugi, and Equisetum ramosissimum. Others are characterized by succulent leaves or twigs to store water and nutrients, such as Suaeda spp., Ipomoea pes-caprae, Calystegia soldanella, and Chenopodium acuminatum. Salsola collina, one of the commonest dominant species, is characterized by deep roots, much like those of its inland counterparts. The plant community generally is less diverse in species, with sole species-dominated stands being rather common. The succession of vegetation follows multiple pathways. Succession occurring at sites closest to the sea or on the foredunes is influenced most severely by sandy and salty conditions, thus belonging to an external factor-driven or primary succession; the succession proceeding above the high tideline belongs to the progressive, autogenic sere.

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399 Miao Z (1996) Temperate steppe type. In: Liao GP, Jia SX (eds) Rangeland resources of China. Science and Technology Press of China, Beijing, pp 188–204 Ning YY, Xü J, Zhang G (2009) Vegetation components and microbe quantity in microbial soil crusts of the grazing land during natural restoration in Horqin sandland, Inner Mongolia. J Inn Mong Univ 40 (6):670–676 Piao QH, Ding GD, Wu B, Qu ZQ et al (2008) Characteristics of vegetation succession in Hulun Buir sandy land. J Soil Water Conserv 22(6):180–186 Pu J, Qi YB, Wang YY, Chu WL et al (2015) Effects of different plant communities on soil microbial biomass carbon, nitrogen and phosphorus in the agro-pastoral transitional zone of northern Shaanxi Province. Agric Res Arid Areas 33(4):279–285 Qin CY (1984) An investigation on the ecology of Meriones unguiculatus. Acta Theriol Sin 4(1):43–51 Ren B (1990) Study on succession of degraded grasslands in Ongniud banner. Grassl Forage 4:39–44 Ren AZ, Gao YB, Wang JL (2001) Root distribution and canopy structure of Salix gordejevii in different sandy land habitats. Acta Ecol Sin 21:399–404 Ren JZ (2008) Prataculture encyclopedia. China Agriculture Press, Beijing Shao YQ, Zhao J, Liao YN (1996) Study on microbial number of Artemisia ordosica rhizosphere in Hobq sandland of Nei Mongol. Acta Sci Nat Univ Nei Mongol 27(1):98–102 Shi DZ (1991) Preliminary investigation on rodents in semi-desert region of Inner Mongolia. Arid Land Res 2:90–93 Shi XF (2010) Study on the diversity of soil faunal groups in different communities in southern Mu Us Sandland. Master’s thesis, Ningxia University, Yinchuan Shi Z, Chen YL, Chen YS, Yourun L, Liu SW et al (2011) Asteraceae, Flora of China, vol 20–21. Science Press/Missouri Botanical Garden Press, Beijing/St. Louis Song MT (1985) Investigation on the herpetofauna of Yulin sandland. Chin J Zool 5:26–28 Song CX (2011) Preliminary study on succession of Artemisia ordosica community in Gonghe sandy grassland. Agric For Sci Technol Qinghai 1:11–14 Su PX, Xie TT, Zhou ZJ (2011) Geographical distribution of C4 plants in desert regions of China and their relations with climatic factors. J Desert Res 31(2):267–276 Tang K (2016) Community structure and diversity of bacteria in biological soil crusts of the Hunshan Dak desert. Master’s thesis, Inner Mongolia Agricultural University, Huhhot Teng XH, Cao CY, Fu Y, Cui ZB et al (2007) Changes of soil enzyme activities and microbial biomass in an age sequence of Caragana microphylla plantations for sand-fixation. Ecol Environ 16 (3):1030–1034 Wang ND (1993) Herperofauna on the Lesser Hinggan Mountains. Chin Wildl 5:12–13 Wang QS, Li B (1994) Preliminary study on biomass of Artemisia ordosica community in Ordos plateau sandland of China. Acta Phys Sin 18(4):347–353 Wang LM, Zhou YL, Zhao LJ (1999) Component analysis for rodents of Ordos Plateau sandland. Acta Sci Nat Univ Nei Mongol 30 (3):377–379 Wang DM, Gao W, Zhao J, Wang HT et al (2002) On the migration law of raptors in Liaoning Province. J Northeast Norm Univ 34(2):78–83 Wang W, Li J, Liu BW, Gao ZX (2005) Bird communities of the grassland and forest ecotone in northeastern Inner Mongolia. J Northeast Forestry Univ 33(4):40–41 Wang HT, Xue PP, He XD, Gao YB et al (2007) Changes in soil substrata in an Artemisia ordosica succession series. Acta Sci Nat Univ Nankaiensis 40(1):87–91

400 Wang SK, Zhao XY, Qu H, Jing XH (2010) Comparison of soil microbial features in mobile dunes from Horqin and Otindag sandlands in northern China. Res Environ Sci 23(12):1516–1522 Wen LY (2007) Studies on population traits of Eremias argus and Phrynocephalus frontalis. J Gansu Sci 19(1):88–90 Wu XD, Shi DZ, Liu Y et al (1994) Analysis of the community structure of rodents ranging in Qubuqi desert and its neibouring regions. Acta Theriol Sin 14(1):43–50 Wu XD, Xue HR, Su JA, Shi DZ et al (1999) Classification and diversity of rodent communities in semi-arid region of Inner Mongolia. Acta Ecol Sin 19(5):737–743 Wu XJ, Yang GS, Xing LL, Chen J (2008) Avifauna and its ecological distribution in Huiteng Gol area, Inner Mongolia. Sichuan J Zool 27 (5):894–896 Xiong Y, Li QK (1987) Soils of China, 2nd edn. Science Press, Beijing Xü J, Ning YY (2010) Impacts of overgrazing and enclosing on biomass and soil factors of microbiotic soil crusts in Horqin sandland. J Desert Res 30(4):824–830 Xü J, Mo Y, Zhu QF (2010) Algae composition and biomass characteristics of microbiotic crusts in Horqin sandland. J Guizhou Norm Univ 28(4):113–117 Yan QL, Liu ZM, Ma JL, Jiang DM (2007) The role of reproductive phenology, seedling emergence and establishment of perennial Salix gordejevii in active sand dune fields. Ann Bot 99:19–28 Yang ZM, Wang Q, Wang XJ, Wang N (2005) Effects of different grazing intensities on the phenology, viability of plants and soil water content. J Agric Sci 26(3):1–3 Yong SP, Guo XD (1985) The sandy vegetation. In: IMNCST-CAS. In: Vegetation of Inner Mongolia. Science Press, Beijing, pp 764–792 Yong SP, Zhu TC, Zhou LH (2007) Steppe. In: Zhang XS, Sun SZ, Yong SP, Zhuo ZD, Wang RQ (eds) Vegetation and its geographic patterns in China. Chinese Geology Press, Beijing, pp 327–385 Yu XD, Zhou HZ, Luo TH (2001) Species diversity of insects on the Ordos Plateau, northwest China. Biodivers Sci 9(4):329–335 Yu XP, Li L, Liang BK (2009) Bird resources. In: Ma F, Zhang JL (eds) Investigation of important terrestrial wildlife resources in China. Forestry Press of China, Beijing, pp 89–225 Yu J, Gao L, Yan ZJ, Wang YQ (2015a) Characteristics of soil seed bank in sand dunes at different succession stages of eastern Qubuqi desert. Chin J Grassl 37(4):80–85 Yu XN, Huang YM, Chen HY, Li XY et al (2015b) Influence of soil moisture on the succession of a Artemisia ordosica community in Mu Us Sandland. J Arid Land Resour Environ 29(2):92–98 Zhang YR, Xing LL, Yang QS (1983) A preliminary study on birds in the Ordos Plateau of Inner Mongolia. Acta Sci Nat Univ Intramong 14(1):45–53

12 Sandy Grassland Ecosystem Zhang Q, Zhao X, Zhao HL (1998) Desert Rangelands in China. Chinese Meteorological Press, Beijing Zhang XK, Dong XW, Liang WJ, Jiang DM et al (2009) Soil nematode community composition and diversity along active sand dunes of Horqin sandland. Soil 41(5):749–756 Zhang DZ, Chen X, He DH (2012) Species diversity of darkling beetles in desert landscape and their role as bioindicators. Chin J Appl Entomol 49(1):229–235 Zhang YF (2017) Soil microbial biomass carbon and nitrogen in three typical communities of desert grassland. Acta Bot Boreal-Occident Sinica 37(2):363–371 Zhao J, Liao YN, Zhang GZ, Shao YQ (1999) Soil microbial ecology in the grassland ecosystem. Chin J Grassl 3:57–67 Zhao HL, Okuro T, LI YL, Zuo XA et al (2009) Changes in plant community during the grazing-restoration process in Horqin sand land, Inner Mongolia. J Desert Res 29(2):229–235 Zhao HL, Zhou RL, Wang J, Zhao XY et al (2011) Desertification process and its mechanism of steppe vegetation in the Hulun Buir sandland. Arid Zone Res 28(4):565–571 Zhao HL, Liu RT, Zhao XY, Zhang TH (2013) Effects of desertification on temporal and spatial changes of soil macro-arthropod community in Horqin sandy grassland. Acta Agrestia Sin 21(2):394–405 Zhao Y, Ren GD (2014) Species diversity and fauna distribution of darkling beetles on the Ordos Plateau. J Inn Mong Agric Univ 35(3):19–25 Zhao N, Zhuang Y, Zhao J (2014) Effects of grassland management on soil organic carbon and microbial biomass carbon. Pratacult Sci 31(3):367–374 Zhao GT, Na HY, Yong P, Fu L, Na LS (2015) Wildlife diversity and protection in Ar Horqin Nature Reserve. Inn Mong Forestry Investig Des 38(1):81–82 Zhong H (2008) Mammalian fauna of Shapotou desert. J Jinggangshan Univ 29(2):16–17 Zhou X, Zuo XA, Zhao XY, Liu C et al (2015) Plant biomass and soil properties during the process of dune restoration in the Horqin sandland. J Desert Res 35(1):81–89 Zhu ZY, Yong SP, Liu ZL (1985) Vegetation of deserts. In: IMNCST (Inner Mongolia-Ningxia Comprehensive Survey Team) Vegetation of Inner Mongolia. Science Press, Beijing, pp 645–722 Zhu ZD (1986) Phenomena of blown-sands and their impacts on lands in humid and sub-humid zones. Chin Deserts 6(4):1–12 Zhu TC, Guo SX, Li XL, Liu Q, Wu XH (1996) Temperate meadow steppe. In: Liao GF, Jia SX (eds) Rangeland resources of China. China Science & Technology Press, Beijing, pp 175–187

Desert Rangeland Ecosystem

Abstract

This chapter focuses on Chinese desert rangeland ecosystems. It introduces in brief the areal extent and provincially based distribution of this ecosystem type; simply discusses the relevant physical features and climatic characteristics at a regional scale; elaborates in great detail upon the flora, fauna, and microflora composing the various desert rangeland ecosystems; and describes in much greater detail the major formations or formation groups of the desert rangeland vegetation nationwide. It also summarizes the standing crops of canopy and root biomass and their allocation pattern of certain important communities. In addition, it expounds on the succession characteristics and their responses to the management and utilization steps of certain desert rangeland ecosystems. Keywords

Vegetal formation · Flora · Fauna · Microorganisms · Root-to-canopy ratio · Succession · Ecological sequence

Deserts, as an important type of natural geographic landscapes, are defined by Chinese researchers as those characterized by sparse vegetation, extremely arid conditions due to very scarce precipitation and intense evaporation, strong continental climates, and commonly soluble saltcontaining soils (Zhang et al. 1980a, b). One of the most important prerequisites for the genesis of the desert vegetation or ecosystem is the low water availability for plant growth, whether physically as occurs in low-rainfall areas or physiologically in alpine and salt deserts. The world’s deserts usually are categorized into the hot (tropical and subtropical), temperate, and alpine desert types according to prevalent climates, and further into subtypes or kinds in light of edaphic properties and interior or coastal locations with respect to the deserts in question. # Springer Nature Singapore Pte Ltd. 2020 L. Li et al., Grassland Ecosystems of China, Ecosystems of China 2, https://doi.org/10.1007/978-981-15-3421-8_13

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Temperate desert ecosystems occur mainly in arid and semiarid regions on Earth, which cover about 4% of the world’s total land surface (West 1983). The arid regions generally include those that have a mean annual precipitation of less than 200 mm, whereas the semiarid regions are those that receive an annual precipitation between 200 and 500 mm. The vegetation is dominated mainly by shrubs for the former, while the dominance of shrubs declines to certain degrees for the latter. The status of the shrub-grass (tussock) mixture is also highly influenced by fires and grazing for certain desert ecosystems. West (1983) designated three temperate desert regions as the major ones in the world, namely the Eurasian-Middle Eastern desert region, the interior western United States of North America desert region, and the Patagonian desert region of Argentina. The Eurasian-Middle Eastern desert region accounted for the largest portion (84%) of the world’s total temperate desert extent (4.9
106 km2). This vast temperate arid and semiarid zone starts from the Danube Delta in the west and stretches across about 100 of longitudes eastward until to northcentral Inner Mongolia. The formation of this subzonobiome had resulted largely from the sheltering effects of the immense Himalayan Mountains and other huge cordilleras on the Qinghai-Tibet Plateau that arrest the humid air currents arising from the Indian Ocean from entering the northern part of the region. As a major part of the above desert zone, the Asian desert begins in the Aral-Caspian region in the west, stretching eastward all the way into Xinjiang, extending further easterly along the Great wall (via the Yellow River Bend), and grading onto the Ordos Plateau. Its western part is known as Middle Asian deserts, while its eastern portion is defined as Central Asian deserts to which the Xinjiang desert region is affiliated biogeographically, with their demarcation line lying to the west of the Junggar desert and to the south of Central Asia. In effect, the two parts differ considerably from each other in many aspects, such as climate, flora, vegetation, and soil. For example, the soil is much more humid during the 401

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spring, the spring vegetation is significantly more developed, and the phonological rhythm is almost 2 months earlier in Middle Asian deserts than in Central Asian deserts (Walter and Box 1983a, b). Desert rangelands in China are found mainly in Xinjiang, which constitute a rather important part of Central Asian deserts, and partially in middle and western Inner Mongolia as well as on the northwestern portion of the Qinghai-Tibet Plateau, with a total area of some 0.63 million km2 that accounts for 16.1% of the nation’s total grassland area and 6.7% of the nation’s total land area (Liao and Jia 1996). Three ecosystem types are assigned to the desert ecosystem type group in China, namely the typical, steppic, and alpine deserts. The purview of this chapter focuses mainly on the three desert types, while those pertaining to the coastal deserts, sandlands, and other azonal deserts have been or will be elaborated upon elsewhere in the volume.

13.1

General Characteristics

Chinese deserts mostly belong to the temperate desert subzonobiome and typically occur on the midlatitude interior basins, high plains, and low mountain areas. The climate is extremely continental, characterized by uttermost drought and intensive solar insolation, with the annual precipitation mostly fewer than 250 mm and an aridity index over 4.0. The summer is scorchingly hot, while the winter is bitter cold. The day and night temperature range is exceptionally great, rendering most of the ordinary plants impossible from entering or becoming tenable. The soils are coarse and poorly developed, accompanied with serious wind erosion, of which the saline-alkali soils are ubiquitously distributed. Windy-dusty days take place almost daily, and cold-drought disasters are annually frequent. However, there indeed is an especially adaptive flora colonizing various biotopes of deserts. In Chinese deserts, the dwarf tree Haloxylon ammodendron is a marker species present in the groundwater-shallow deserts. It is usually 1–3 m tall, with an obvious main stem, while its twigs fall annually. Dominant hyperxerophilous succulent shrubs include Ephedra przewalskii, Zygophyllum xanthoxylon, several species of Nitraria (sphaerocarpa, tangutorum, roborowskii, sibirica), Gymnocarpos przewalskii, Ammopiptanthus mongolica, Tetraena mongolica, Lycium ruthenicum, and Calligonum species, some of which are the Tethys Sea remnant species. Of special interest, some shrubs, such as Calligonum spp., can carry on photosynthesis by their tender twigs. The thorny scrubby species Caragana tibetica usually dominates the steppic desert, while C. brachypoda, C. stenophylla, and Potaninia mongolica are most dominant at sandy-gravelly sites. Dominant on the foothills of mountains and hills of the steppic desert region are Helianthemum

Desert Rangeland Ecosystem

songoricum and Convolvulus tragacanthoides. Salt-excreting dwarf shrubs such as Reaumuria soongorica and R. trigyna primarily colonize saline soils at localized locations. Semishrubs virtually are the most dominant and widespread in Chinese deserts. They usually occur a bit more northward and are later in floristic evolution than shrubs. Several subgroups can be divided, including (1) succulent semishrubs, comprising a number of hyperxerophilous species of the family Chenopodiaceae, notably Salsola laricifolia, S. passerina, S. abrotanoides, and Anabasis brevifolia that occur in the intermountain basins, piedmont diluvial plains, and Gobi areas of the Alxa desert and the Mazongshan area; Kalidium gracile, K. foliatum, K. cuspidatum, and Halostachys belangeriana that usually are dominant at humid, salty desert biotopes; and thorny species such as Oxytropis aciphylla that are dominant at localized sites; (2) xerophilous semishrub species, which are most diversely found in the sandy-gravelly deserts, including Ceratoides latens and a few others, apart from Artemisia sphaerocephala, A. ordosica, Hedysarum scoparium, and H. mongolicum that are most prominent in the sandy deserts; and (3) dwarf semishrubs, such as Ajania achilloides, A. trifida, A. parviflora, and Artemisia frigida that are the important associates in the steppic desert. Perennial herbs generally come from the steppe, mostly being insignificant associates in the deserts. The bunchgrass synusia consists primarily of short grasses, notably Stipa spp., Cleistogenes songorica, and Ptilagrostis species. Rhizomatous species include Psammochloa mongolica and Pennisetum flaccidum that usually colonize semifixed sand dunes. Bulbaceous species, notably Allium spp. (mongolicum, polyrhizum, tenuissimum), are important associates in the steppic desert. Xerophilous forbs comprise drought-tolerant dicots, such as Heteropappus altaicus, Astragalus membranaceus, Asparagus gobicus, Oxytropis aciphylla, Convolvulus ammannii, Plantago asiatica, Lagochilus ilicifolius, Cymbaria dahurica, Scorzonera muriculata, Gueldenstaedtia verna, Glycyrrhiza uralensis, Acanthophyllum spp., Limonium spp., Alhagi spp., and Karelinia caspica. Common annuals and biennials comprise sages Artemisia scoparia, A. blepharolepis, and A. intricata, and Neopallasia pectinata, all of which are highly dependent on the summer rain to grow; the species of Chenopodiaceae such as Suaeda spp. (przewalskii, corniculata, glauca), Atriplex centralasiatica, and A. sibirica that pioneer salt habitats; and the species Salsola pestifer, S. gobicola, S. collina, S. beticolor, Halogeton arachnoideus, H. glomeratus, and Bassia divaricata that occur in the sandy-gravelly deserts, as well as annual grasses Aristida adscensionis, Pappophorum brachystachyum, Eragrostis minor, Chloris virgate, and Tragus berteronianus that are present at sites of stress or disturbance as pioneering species.

13.2

Steppic Deserts

Ephemerals, ephemeroids, and transients are much less conspicuous in Chinese deserts than in other Central Asian deserts. Important ephemeroids here include Carex physodes, C. pachystylis, Poa bulbosa var. vivipara, Eremurus spp., Tulipa spp., Gagea spp., and Ferula species. Annual shortliving species include those of Bromus, Eremopyrum, Schismus, Alyssum, Malcolmia, Lepidium, Leptaleum, Tauscheria, Tetracme, Goldbachia, Koelpinia, Lappula, Nonea, Nepeta, Plantago, and Trigonella (Zhang et al. 1980a, b; Zhu et al. 1985; Song 1996; Miao 1996).

13.2

Steppic Deserts

13.2.1 Physical Features The Chinese steppic desert has been formed under the influence of temperate arid climatic conditions, dominated by xerophytic and super-xerophytic dwarf semishrubs,

403

semishrubs, or dwarf shrubs, with well admixtures of superxerophilous perennial and annual herbs in varying amounts (Miao 1996). This rangeland occurs mainly in Inner Mongolia, occupying a narrow belt where the desert joins the steppe, and concentrated on the northwestern Ordos Plateau, the Great Bend of the Yellow River, and eastern Alxa. It starts on the western Ulanqab plateau in the east and extends southwestward through the Langshan Mountains to the Helan Mountains, and then it turns northwest through the north of the Qilian Mountains. This zone runs more than 1000 km discontinuously from northeast to southwest, while its eastto-west width varies between 20 and 100 km (Fig. 13.1). Another major portion of this desert is found in Xinjiang, the vegetation of which is primarily scattered in the piedmont areas of the large mountains and fringes of the interior basins (Table 13.1). In the Chinese vegetation regionalization scheme, the main (zonal) body of this type of vegetation belongs to the Alxa high plain steppic desert and semishrub and shrub

Fig. 13.1 Outline map of Chinese deserts. (Adapted from RRC, Image regeneration courtesy of CY Song)

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Table 13.1 Regional distribution of the steppic desert Province Inner Mongolia Tibet Gansu Ningxia Xinjiang Total

2

Area (hm ) 5,354,087 107,098 521,006 545,140 4,146,087 10,673,418

Prop. (%) 50.1 1.0 4.9 5.1 38.8 100.0

desert division, the eastern desert subregion, and the temperate desert region of China (Zhang et al. 2007). The landform of this division is dominated by vast sandy-gravelly high plains where deserts Qubuki, Ulan Buh, and Tengger extend, interspersed sparsely with several high mountains. In addition, the Yellow River flows through its southern part, giving rise to various alluvial and lacustrine plains. The plains are generally 1000–1400 m above sea level, while the mountains are mostly 1800–2000 m in elevation. Total heat and aridity are lower here than in the typical desert subregion but considerably higher than in the desert steppe zone. The overall mean annual temperature ranges from 6.0 to 9.0  C, while those of July and January are 22–25  C and 13 to 10  C, respectively, with an annual cumulative temperature (10  C) of 3000–3500  C. The annual precipitation averages 150 mm or so, varying mostly between 40 and 100 mm in western Alxa and between 100 and 200 mm in eastern Alxa (Wang et al. 1985a, b). Two subtypes of brown soils are the most principal ones that underlie the steppic desert vegetation. In the Ulanqab region, the orthic brown soil is most prominent, characterized by the occurrence of sandy and gravelly substrata as well as pseudo-crusts. The humus layer generally is thin, with a SOM content between 1.0 and 1.8%; the calcic horizon is high-positioned in the soil profile, usually present at a depth of 20–30 cm, with a thickness of 20–30 cm. The soil is alkaline throughout, with pH values being from 9.0 to 9.5 with increasing soil depth. Within the scope from western Ordos to eastern Alxa, the light brown soil, another subtype, becomes more dominant, in which calcium accumulation is much weaker and shallower in position than that in the above subtype. Its SOM content is generally low, from 0.5 to 1% in most cases. In addition, salinization occurs widely in this soil, with salt contents mostly between 0.5 and 1.0% and pH values of 9.0–10.0 (Miao 1996). Relevant knowledge has been elaborated upon in greater detail in Chaps. 2 and 8, to which interested readers may be referred.

13.2.2 Floristic and Ecological Traits Phytogeographically, the flora of the steppic desert belongs to Alxa or the Gobi botanical province. The plant species

Desert Rangeland Ecosystem

richness compares favorably with other floral provinces of the Central Asian desert subzonobiome. Some 384 species belonging to 203 genera and 52 families are expected to occur in the plain areas. Of these, species of Ammopiptanthus, Potaninia, and Tetraena are the native shrubs. The steppic desert usually contains a certain number of desert steppe components, the commonest of which are Stipa spp., Cleistogenes spp., Agropyron spp., Allium spp., Ptilagrostis pelliotii, and Carex rigescens, which render it steppe-like. In addition, aestival annuals are the constant components, although they usually play an insignificant role in the vegetation. The dwarf semishrubs commonly seen in the desert steppe often are the constant associates here, such as Ajania spp. and Oxytropis spp. (Yong et al. 1985). The vegetation is generally sparse and species poor, with a mean coverage of 10–30% and a density of ten odd species per square meter. The community is rather distinct in structure, with three canopy sublayers commonly found, composed of semishrubs, short bunchgrasses, and transient annuals separately. The herbage is generally of low level in yield and inferior in quality. In addition, the yield is rather variable among years, with the coefficient of variances averaging 45.4% (Miao 1996).

13.2.3 Vegetation 13.2.3.1 Form. Seriphidium kaschgaricum This steppic desert is found mainly on the low mountains, piedmont diluvial fans, and alluvial plains at altitudes from 400 to 1400 m in the Ili and Altay regions, and in part on the low mountains and hills at altitudes from 1000 to 1500 m (exceptionally up to 2400 m) in the Aksu region. Dominant soils are sierozem and calcic desert soils, with their sandygravelly substrata often outcropped on the ground. S. kaschgaricum, dominant throughout, is a subshrub 30–35 cm tall, characterized by a vertical woody rootstock that usually branches from its lower part; its branches are slender, erect, and densely arachnoid pubescent or glabrescent. It may occupy slopes, the Gobi Desert, dry valleys, rocky hills, and roadsides (Shi et al. 2011). The species composition of the vegetation is relatively rich, with Kochia prostrata, Stipa spp., Agropyron spp., Nanophyton erinaceum, and Eremopyrum orientale as important associates; grasses, sages, and forbs each accounts for 38%, 45%, and 17% of the total standing crop of canopy biomass (Miao 1996). 13.2.3.2 Form. Caragana Korshinskii C. korshinskii, a shrub usually or dwarf tree at certain biotopes, is 1–4 m tall; its branches are golden yellow and shiny, with branchlets being pubescent; its leaves are pinnate, with leaflet blades lanceolate to narrowly oblong.

13.2

Steppic Deserts

Ecologically, it is hyperxerophilous and deciduous, with vigorous canopy growth and deep, widespread roots, being able to generate new roots at the base of the trunk when buried. It has an altitudinal range of distribution basically from 900 to 2400 m, the stands of which are found primarily in Gansu, Inner Mongolia, Ningxia, Qinghai, and Xinjiang. This kind of vegetation is most characteristic of the eastern Alxa-western Ordos steppic desert, where it typically occurs in the western Qubuqi sandland, the northwestern portion of the Tengger desert, and the Ulan Buh desert. The stands most often colonize the semifixed and mobile sand dune fields with hard substrata underneath, the sand layer of which usually contains small gravels and rubbles in variable amounts. The canopy generally is sparse, with isolated shrub clumps dispersed randomly on the ground. Artemisia ordosica is a usual subdominant component in the community, while Oxytropis aciphylla, A. frigida, and Lespedeza potaninii are also frequent and abundant. Common accompanying shrub and semishrub species include Z. xanthoxylon, Ammopiptanthus mongolicus, Convolvulus fruticosus, and Calligonum mongolicum; common perennial grasses are Stipa glareosa and Cleistogenes songorica; forbs include Allium mongolicum, Astragalus galactites, Heteropappus altaicus, and Corispermum patelliforme. In addition, several annuals occasionally are present in varying amounts. The overall species number present in the community is relatively large, while the saturation density is rather low, with 3–8 species usually found per square meter. C. korshinskii makes up the bulk of the total herbage yield (usually 70% or so), with perennial grasses and annual herbs accounting for 10% and 20%, respectively.

13.2.3.3 Form. Caragana tibetica This formation is most typical and conspicuous of the steppic desert vegetation in terms of its affinity to the steppe (Miao 1996), which is also one of the most important components of the Alxa-Ordos steppic desert. It generally occupies the interface areas between the desert steppe and the steppic desert, and may extend into the desert region in different directions. It centers on the western Ulan Qab plateau and the western Ordos Plateau, with a scattered distribution at the southeastern edge of the Alxa high plains, on the western piedmonts of the Helan Mountains, as well as in northern Gansu. Its stands mainly occur on the gently undulating high plains, moderate hilly areas, and piedmont diluvial and alluvial plains at altitudes between 1100 and 1200 m. The light brown soil is most prominent in these areas, usually being covered with a layer 10–15 cm thick of aeolian sand or coarse gravels. About 68 seed plants occur in the various communities, which belong to 45 genera within 24 families. Of the genera, Artemisia (5), Stipa (4), Allium (4), and Caragana (4) contribute exactly one-quarter of the total species. In terms of ecotype, more than 85% of the species are xerophilous, of

405

which 5 are hyperxerophilous desert species, 44 being xerophilous steppe species, 4 being euryxerophilous, and 5 being mesoxerophilous. By contrast, only 11 species are mesophilous, all being annual or biennial herbs, the presence of which is dependent heavily on the summer rain to complete their life cycles (Zhu et al. 1985). Phytogeographically, the Central Asian desert element is rather prominent, which accounts for 23 species in total, including 9 Gobi, 11 desert and desert steppe, 1 Gobi Desert, and 2 Alxa desert endemic species. 19 are Central Asian steppe species, comprising 10 Dahuric-Mongolian species, 4 Mongolian steppe-specific species, 1 northeast China species, and 4 KazakhstanMongolian steppe species. In addition, the Palaearctic, Holarctic, Tethys Sea, and widely distributed elements each accounts for 10, 3, 3, and 4 species, respectively, whereas 4 species remain unidentified presently. C. tibetica is a shrub 30 cm tall and cushion shaped; its old branches are grayish yellow to grayish brown; current-year branchlets are bright grayish brown and densely pubescent. Individuals may be found in Gansu, western Inner Mongolia, Ningxia, Qinghai, northern Shaanxi, western Sichuan, and Tibet. The plant of C. tibetica grows vigorously, with close clumps distributed evenly on the ground, the density of which may reach about 25 clumps/100 m2. Its individual clump usually is 10–15 cm tall, with a diameter of 110–140 cm and a canopy density of 0.1–0.3. The species composition of the vegetation is relatively rich, characterized by a considerable number of steppe species, with a distinct synusia differentiation in the stands. The most frequent and abundant herbaceous species are three species of Stipa, i.e., S. glareosa, S. klemenzii, and S. breviflora, which usually form a conspicuous bunchgrass synusia in the community; constant associates comprise the perennial herbs Cleistogenes songorica, Asparagus gobicus, Heteropappus altaicus, Lagochilus ilicifolius, Artemisia frigida, Ajania achilloides, Ptilotrichum cretaceum, and Convolvulus ammannii, and several annuals as well, mainly Aristida heymannii, Eragrostis pilosa, Salsola collina, Artemisia scoparia, and Neopallasia pectinata. It should be noted that this formation has many associated species and major herb synusiae in common with the Stipa glareosa and S. breviflora desert steppes, especially the perennial grass, semishrub, xerophilous forb, and annual synusiae, indicating its close affinities to the desert steppe. The species density is the highest of its kind, with 12–28 species per 200 m2 or 5–12 species per square meter in the herb stratum usually being measured. The canopy density averages 0.3 or so, with a half contributed by herbs. Harvestable biomass for herbage is made up mainly of the shrubs (50.4%) and perennial herbs (38.1%), with only small amounts of semishrubs (9.3%) and annuals (2.2%); by species group, legumes, grasses, and sages make up 50.9%,

more salty and moist

Fig. 13.2 Schematic representation of ecological relations among different C. tibetica communities of the steppic desert region. (Modified from Zhu et al. 1985)

13

more sandy, gravelly, stony

406

C. tibetica + Artemisia ordosica ass.

C. tibetica + Ajania ass.

Desert Rangeland Ecosystem

C. tibetica + Artemisia frigida ass.

ൕC. tibetica-dwarf semi-shrub meadow C. tibetica + Oxytropis aciphylla ass.

C. tibetica + Stipa glaerosa ass.

C. tibetica + Ceratoides latens ass.

C. tibetica + Stipa gobica ass.

C. tibetica + Zygophyllum ass.

C. tibetica + Stipa brevifloras ass.

C. tibetica + Reanmuria ass.

C. tibetica + Pennisetum ass.

ൖC. tibetica shrub desert C. tibetica + Allium mongolica + A. polyzzhizum ass.

22.1%, and 19.7% of the total herbage yield, respectively. This formation previously was comprised of several Caragana species (notably microphylla, stenophylla, and intermedia) that have disappeared in recent years, which has been attributed partially to the competitive exclusion by C. tibetica and other shrub species (Zhang et al. 1980a, b). Ecological relations among the different C. Tibetica communities are displayed in Fig. 13.2.

13.2.3.4 Form. Ammopiptanthus mongolicus This formation is restricted to Alxa Zuoqi in the southeastern Alxa high plains that belongs to the middle part of the Tengger desert and abuts Wuhai on the northwestern Ordos Plateau, with a rather small standing area. Its stands most often inhabit the mountain and hill slopes with stark rocky outcrops. The species composition of the vegetation is relatively diverse, with 70 odd higher plant species present in the various communities which belong to 51 genera and 23 families. Of the families, Compositae (10 spp.), Gramineae (9), Chenopodiaceae (7), Zygophyllaceae (5), and Leguminosae (3) contain the largest number of the species. Of the genera, Artemisia, Caragana, Stipa, Salsola, and Allium each contains at least 3 species. By life-forms, 9 shrub, 7 dwarf shrub, 5 semishrub and dwarf semishrub, 16 perennial forb, 7 bunchgrass, 2 rhizomatous, 3 bulbaceous, and 11 annual-biennial species are recognizable. One sees that there occur more numerous steppe species whereas less typical desert species in this steppic desert, which reflects fully its steppic nature. A. mongolicus is the only species of its genus found in China. It is a hyperxerophilous, evergreen shrub, usually 1.5–2 m tall; its bark is yellowish brown; stem is terete,

ൗC. tibetica-xeric grass desert C. tibetica + Achnatherum splendens ass.

൘C. tibetica – Allium, tall grass desert

weakly ridged, and glabrescent; and leaf is one- or threefoliolate. It may colonize sand dunes, gravelly slopes, and terraces beside ravines, found primarily in Gansu, Inner Mongolia, Ningxia, and western Xinjiang (Kashi) in China as well as in the neighboring countries Kazakhstan, Kyrgyzstan, and southern Mongolia (Li et al. 2010). A. mongolicus is dominant throughout in the communities. Its canopy usually is 50–70 cm tall, with clumps 90–160 cm in crown width and a density of 40–60 clumps in a 10
10 m2 quadrat. Stipa breviflora often is the constant subdominant species in the community, which usually forms a fairly conspicuous bunchgrass synusia in association with S. glareosa and S. gobica. Other common associates encompass Cleistogenes songorica, desert Artemisia spp., and several annual grasses. The stands are relatively closed and clearly layered in structure. The herbage biomass is composed mainly of A. mongolicus (50%) and annuals (33%), with semishrubs and perennial herbs in turn making up 7% and 10% only. Of special attention, A. mongolicus is an older remnant desert species, and used to occur in association with other shrubs or semishrubs such as Z. xanthoxylon, Reaumuria soongorica, and Caragana stenophylla. The ecological sequence of the Ammopiptanthus mongolicus formation is shown in Fig. 13.3, which usually may be observed in the steppic desert region.

13.2.3.5 Ceratoides latens–Stipa glareosa Steppic Desert This desert is found mostly in Xinjiang and occupies mainly the piedmont alluvial plains of the Altay Mountains down to the fringes and mountains west of the Junggar Basin, and appears in part on the low mountains and hills west of

13.2

Steppic Deserts

407 A. mongolicus + Ajania association

A. mongolicus + Zygophyllum association

more stony

A. mongolicus + Stipa spp. association moister

drier

A. mongolicus + Zygophyllum + Ajania association more sandy

A. mongolicus +Oxytropis

Fig. 13.3 Schematic representation of the ecological sequence of the Ammopiptanthus mongolicus formation in the steppic desert region. (Modified from Zhu et al. 1985)

Barikun, with a very small portion found in Alxa Zuoqi of the southwestern Tengger desert. The most frequent soils supporting this kind of vegetation in Xinjiang are the brown soil and the gray-brown desert soil with sandy, loamygravelly, or stony substrata, and eolian sandy soils in Alxa. Its species composition differs substantially between the two regional kinds of this formation. In Xinjiang, aside from the subdominant species S. glareosa, the commonest accompanying semishrub species are Reaumuria soongorica, Brachanthemum fruticulosum, Anabasis brevifolia, and Salsola arbuscula; perennial herbs are less abundant, while goosefoot annuals are rather frequent. In the herbage biomass composition, species of Chenopodiaceae (goosefoot family) contribute two-thirds of the total yield, while grasses, legumes, and other families, notably composites, make up 10.1%, 2.2%, and 21.2%, respectively. By contrast, in the Alxa steppic desert, constant associates mainly are dwarf semishrubs and perennial herbs, notably Hippolytia trifida, Ajania achilloides, Allium spp., and Peganum nigellastrum, with 3–6 species usually being observed per square meter. The stands are rather canopy-closed, and the herb stratum usually is 10–14 cm tall, whereas the shrub stratum may reach a height of 30–40 cm (exceptionally 100 cm); the herbage yield averages 512 kg/hm2, of which semishrubs account for more than two-thirds, while grasses account for 21% (Miao 1996).

13.2.3.6 Salsola passerina: Short Bunchgrass Steppic Desert This formation is a zonal kind of vegetation, being most characteristic of the succulent dwarf semiarid desert. It occurs mainly on the northwestern Ulan Qab plateau, in Alxa Zuoqi within the Tengger desert, and slightly on the western high plains of the Xilin Gol grassland region, with which alkalinized light brown soils are most closely associated. Generally, its extent is to the south of the 45 north latitude line, centering in the Alxa desert region, and stretching

through the eastern Qilian Mountain region and down to the Shule River catchment of Gansu at roughly 37 north latitude. Its stands also occur in the Xinjiang mountain areas at altitudes usually from 800 to 1200 m and up to 2500 m at most. The annual precipitation spatially varies between 50 and 150 mm, which is the typical range of the steppic desert climate. A total of 88 species have been recorded in its various communities, belonging to 57 genera and 20 families, with Chenopodiaceae (18 spp.), Compositae (16), Gramineae (13), Zygophyllaceae (10), Leguminosae (6), and Liliaceae (4) containing the most species (Zhu et al. 1985). The other 14 families contain the remaining 21 species. In terms of genera, Artemisia (7) and Salsola (6) have the most species. Phytogeographically, Gobi species are most numerous (30), followed by Mongolia species, the Central Asian desert species (12), and the Tethys Sea species (8). By ecotypes, 27 species are hyperxerophilous, 34 being xerophilous, and 13 being mesoxerophilous that occur in localized humid biotopes. In addition, 10 are salt-tolerant species. Individuals of S. passerina usually are evenly dispersed on the ground, 200–800 of which may be counted in a 10
10 m2 quadrat. The bunchgrass synusia composed of Stipa glareosa, S. klemenzii, and Cleistogenes songorica is rather prominent. Common associates are basically those also occurring in the above vegetation. The vegetation generally is sparse and short. Goosefoot species make up a bit more than two-thirds of the total herbage yield, while grasses and composites make up 16% and 1%, respectively. By lifeforms, shrubs, semishrubs, perennial herbs, and annual herbs account for 34.4%, 32.2%, 31.3%, and 2.1% of the total herbage yield, separately. The ecological sequences of this formation driven by different environmental factors are displayed in Fig. 13.4.

13.2.3.7 Reaumuria soongorica: Short Bunchgrass Steppic Desert This is the single largest and most widespread steppic desert in China, being found basically in the same extent as that of the above desert. The plant of R. soongorica commonly is 8–15 cm tall and 35–75 cm in bunch width, with a density of 107–173 clumps in a 10
10 m2 quadrat. The subdominant species and constant associates of the vegetation basically are the bunchgrasses that also occur in the above vegetation. However, the stands hereof are much sparser and shorter. Grasses are most prominent in the total herbage composition, which account for 35.1%, whereas goosefoot species decrease noticeably in abundance, which make up only 11.4% of this total; composites make up 9.2%, while Tamarix spp. make up a rather high proportion (up to 21%). By lifeforms, shrubs and perennial herbs make up the absolute majority of the total canopy biomass, the proportions of which in turn are 57.1% and 39.3%. The ecological sequence

408

13

Fig. 13.4 Schematic representation of the ecological sequences of the Salsola passerina formation in the steppic desert region. (Modified from Zhu et al. 1985)

S. passerina + Cleistogenes ass.

S. passerina + S. breviflora ass.

Desert Rangeland Ecosystem

S. passerina + Carex ass.

S. passerina + Allium ass.

More gravelly

S. passerina + Cleistogenes ass.

S. passerina + Stipa gobica ass.

S. passerina + Stiap glaerosa ass.

S. passerina + Ajania + Artemisia spp. ass.

More salty and humid

R. soongorica + short bunchgrass community Dwarf semi-shrub community

less gravelly less gravelly

R. soongorica + Allium spp. community moister

R. soongorica + Caragana + bunchgrass community less

gravelly

R. soongorica + Caragana community

Fig. 13.5 Schematic representation of the ecological sequence of the Reaumuria soongorica formation in the Alxa steppic desert region. (Modified from Zhu et al. 1985)

of this formation is shown in Fig. 13.5, which is observed primarily in the Alxa steppic desert region.

13.2.3.8 Sympegma regelii–Stipa glareosa Steppic Desert S. regelii is 30–150 cm tall, with its roots black-brown and stout; its old branches are much more branched, yellow-white to gray-brown, and usually fissured, whereas the annual branches are dwarf and single-internoded (Zhu et al. 2003). This species is an extremely important forage provider in the desert and semidesert areas, the annual branches of which are preferentially eaten by sheep and camels. The S. regelii vegetation is the only kind that occurs on the high mountains, large expanses of which are found mainly on the vertical belt of the Mazong Mountains at altitudes up to 2000 m and that on the southern side of the Tianshan Mountains at altitudes between 2000 and 2200 m, with the soils extremely stony. Ecologically, S. regelii is a hyperxerophilous semishrub species, being relatively vigorous and dominant throughout the various communities; the usual subdominant species is Stipa glareosa. Annual shortgrasses, noticeably Enneapogon brachystachyum and Aristida heymannii, are particularly prominent; other important associates are basically those that commonly occur in the various steppic deserts discussed above. 13.2.3.9 Form. Potaninia mongolica As the only species of the older monotypic genus Potaninia, P. mongolica is endemic to the Alxa steppic desert (Zhu et al.

1985). Phytogeographically, it belongs to the Mongolian element, and is among the few members of the family Rosaceae that are related to the southern African genus Cliffortia (Walter and Box 1983a, b). Ecologically, it is a hyperxerophilous semishrub, regenerating by intensive branching at the base. Its plants can tide over extreme drought in a fashion of false death, being able to flower for a second time. This formation basically is confined to the desert portions within its extent, being distributed mainly in the western Ulan Buh desert and the northern Badain Jaran desert, with its southern limit at the southern edge of the Tengger desert. Its habitats mostly are dominated by gray-brown desert soils with substrata of sandy-gravelly Gobi, usually being covered with a thin layer of sand. The mean annual temperature is roughly 7  C, with an annual cumulative temperature of 3000–3600  C; the annual precipitation averages 100 mm or so, with a humidity index of around 0.13. The plants may grow in clumps on various landscapes, either the piedmont plains and intermountain or inter-hill wide valleys or the low-lying sites and gentle sectors on the common plains, being highly adapted to sandy while less to gravelly environments (Zhu et al. 1985). The abundance of the vegetation is closely related to the depth of sand cover on the ground. The stands usually develop best on sectors with a sand cover of 10–15 cm in thickness, while often are stunted at sites where the sand cover exceeds 20 cm in depth, whereas may give way to Zygophyllum xanthoxylon stands as the sand cover becomes further thicker; on the other hand, with intensifying degrees of gravelly substrata, the stands usually are replaced by those dominated by Salsola passerina or Anabasis brevifolia. The species composition of the P. mongolica steppic desert is relatively rich, the total number of which may attain 85 species, belonging to 56 genera and 21 families (Zhu et al. 1985). Major families are Compositae (17 species), Chenopodiaceae (14), Gramineae (12), Leguminosae (10), and Zygophyllaceae (8), while species-rich genera in sequence are Artemisia (5), Salsola (5), Caragana (4), Zygophyllum (3), Nitraria (3), Astragalus (3), and Stipa (3). Floristically, the Gobi Desert (Central Asian desert) element is most prominent (containing more than 40% of the total species), with the Gobi-Alxa sub-element in particular; nest in species number are the Mongolian steppe element (20%)

13.3

Typical Deserts

409

and the Tethys Sea element (10%). Several relic endemics have been conserved in this desert, such as Tetraena mongolica, Ammopiptanthus mongolicus, Reaumuria trigyna, and Gymnocarpos przewalskii. Several common synusiae are recognizable in the various communities of this formation, including (1) the hyperxerophilous dwarf shrub synusia, consisting mainly of Potaninia mongolica, Nitraria sphaerocarpa, Caragana brachypoda, C. stenophylla, and Convolvulus tragacanthoides; (2) the hyperxerophilous, salt-excreting, dwarf shrub synusia, notably Reaumuria soongorica and R. trigyna; (3) hyperxerophilous shrubs, mainly Zygophyllum xanthoxylon; (4) xerophilous dwarf semishrubs, comprising mainly Salsola spp. (passerina, laricifolia, abrotanoides), Anabasis brevifolia, and Sympegma regelii; (5) hyperxerophilous semishrubs, mainly Ceratoides latens; (6) xerophilous steppic dwarf semishrub synusia, comprised of Ajania spp. and Artemisia spp.; (7) short bunchgrasses, comprising Stipa spp., Cleistogenes songorica, and Ptilagrostis pellioti; (8) xerophilous Allium species, mainly A. polyrhizum, A. mongolicum, and A. tenuissimum; (9) perennial forbs, which usually are not prominent, consisting of Echinops gmelinii, Scorzonera divaricata, and Z. pterocarpum; and (10) annuals, including sages, goosefoot species, and grasses. The canopy of the vegetation is distinctly defined by three strata. The shrub stratum generally is more than 50 cm in height, dominated by Z. xanthoxylon; the dwarf shrub and dwarf semishrub stratum is 20–35 cm tall, being the fundamental layer; the herb stratum is sparse and uneven in most cases, usually fewer than 20 cm in height. Although being rich in species, the vegetation is rather sparse, usually ranging in coverage from 10–20% to 30–40%, averaging 5–15%. Relevant areas and community traits of the major steppic desert formations in China are summarized in Table 13.2.

13.3

Typical Deserts

The typical desert is the most widespread type of Chinese deserts and is distributed extensively in the temperate zone of north China. Its formations occur mainly in the interior basins

and low mountain areas of midlatitude regions, being influenced by strong continental dry air currents. Its environment is characterized by an extremely droughty soil moisture status, intensive solar insolation, and frequent windy-dusty days. The mean annual precipitation generally is fewer than 250 mm, which is far surpassed by the annual evaporation, resulting in an aridity value of mostly above 4. The weather is boiling hot in summer and bitter cold in winter, with considerable seasonal variations and substantial diurnal differences in temperature. Physical weathering and soil erosion are extremely intense, while sieving and translocation of substrata are substantial, engendering the widespread presence of the soil parent materials made up of various aeolian, sandy-gravelly deposits. Under such conditions, the soils are poorly developed, characterized by coarse-textured, thin, SOM-poor, but salt-rich soil layers. The vegetation generally is scarce and scattered, or absent completely in quite a few cases.

13.3.1 Physical Features Chinese typical deserts lie roughly to the west of 108 E and the north of 36 N, occurring mainly in the Junggar (also Dzungaria in foreign literature) and Tarim basins of Xinjiang, the Qaidam basin of Qinghai, and the Alxa high plains in the west, and confined to the Ordos Plateau part of west-central Inner Mongolia in the east, with a cumulative area totaling up to 0.45 million km2 (Table 13.3). The major landforms include interior basins, mountains of varying heights, and plains of various sizes (Zhang et al. 1980a). Four immense cordilleras ranging west-to-east by and large are environmentally most influential, i.e., the Altay, Tianshan, KunlunAltun, and Qilian Mountains, which stretch separately over the vast land of northwest China, delimiting an array of distinctly isolated deserts in varying areas. Among these, the best known are the Taklimakan desert (337,600 km2), Gurbantünggüt desert (48,800 km2), Kuruktag desert (19,500 km2), Qaidam desert (34,900 km2), Hexi Corridor desert (18,400 km2), Badain Jaran desert (44,300 km2), Tengger desert (42,700 km2), and Ulan Buh desert

Table 13.2 Areas and community traits of major steppic desert formations in China Formation/association Seriphidium kaschgaricum C. korshinskii–A. ordosica C. tibetica–Stipa spp. Ammopiptanthus mongolicus C. latens–Stipa glareosa S. passerina–bunchgrass R. soongorica–bunchgrass S. regelii–Stipa glareosa Potaninia mongolica

A 489,153 97,519 588,457 52,269 1,168,309 1,443,600 1,848,573 702,552

SCB 327 846 844 340 433 459 366 313 220

H 20–25 150–200 10–15 50–70 20–40 7–15 6–12 7–15 >50

C 20–40 5–15 15–20 30 15–30 7–16 7–10 30 5–15

Abbreviations: A area (hm2); SCB standing crop of biomass (kg/hm2); H height (cm); C coverage (%); SD species density (no./m2)

SD 16 3–8 9–12 5–6 3–6 2–6 2–9 3–6 4–12

410

13

Table 13.3 Regional distribution of Chinese typical deserts Area (hm2) 16,924,818 45,333 4,804,418 42,640 2,038,517 21,205,085 45,060,811

Province Inner Mongolia Tibet Gansu Ningxia Qinghai Xinjiang Total

Prop. (%) 37.6 0.1 10.7 4.5 0.1 47.1 100.0

(9900 km2) (Zhang et al. 1998). They most often cover the piedmont rolling plains, diluvial-alluvial plains, lacustrine lowlands, and other localized landforms, and also form the basal belts of the montane vegetation that feature the high mountains. The Alxa Gobi lies mainly in the border area neighboring Outer Mongolia, with the land surface being rocky and clothed with layers of gravels and rubbles, and taking on a yellow-brown appearance. In the Chinese vegetation regionalization scheme, the temperate desert region is subdivided into two parts, i.e., the western subregion and the eastern subregion. The western comprises two desert zones, namely the Junggar Haloxylon semishrub desert zone and the Tacheng Artemisia desert zone. By contrast, the eastern subregion is further categorized into five zones or divisions, including three temperate ones and two warm temperate ones which together contain 12 desert areas (Zhang et al. 2007).

13.3.2 Climates The typical desert vegetal region generally is rich in sunshine and heat resources. More specifically, the annual sunshine length usually reaches 2000–3600 h, with an annual radiation heat rate amounting to 120–175 Kcal/cm2. Annual cumulative temperatures (10  C) may exceed 2500  C in much of the plains, of which that of the Tarim Basin can arrive at

Desert Rangeland Ecosystem

4000  C on average and that of the Turpan Basin commonly attains 5500  C or so; those of the Junggar Basin and the Alxa high plains range from 3100 to 3900  C in the south and from 2200 to 2800  C in the north, while that of the Qaidam Basin varies between 1500 and 2000  C. Mean annual temperatures in Tarim, Turpan, and Hami deserts range from 8.0 to 14.0  C, with that in January between 0.0 and 10.0  C. The annual means in the Hexi Corridor, Alxa, Hetao (the Ningxia bend), and the Junggar Basin range from 0 to 9.0  C, with the means of January mostly being lower than 10.0  C. By contrast, the mean annual temperatures at altitudes above 2500 m on the Tianshan and Qilian Mountains are generally below 5.0  C. The Qaidam desert has a mean annual temperature of 3.6  C and a monthly temperature in January of 11.6  C. The maximum temperatures occur mostly in July, being between 20 and 25  C for most regions, with that in the Turpan desert exceptionally attaining 33  C and that in the Qaidam desert being as low as 16.7  C (Table 13.4). The inter-month temperature range varies between 26.0 and 42.0  C, while the within-year extreme temperature range can be as large as 60.0–70.0  C among the different desert regions. A diurnal temperature range of 30–40  C is commonly measured in the Dunhuang region, Gansu. The mean annual precipitation generally is fewer than 200 mm, with that in 80% of the total extent being fewer than 100 mm. It is less than 50 mm at the fringes and fewer than 25 mm in the interior of the Tarim desert. By contrast, the Junggar desert usually receives an annual precipitation of 150–200 mm. Spatially for most of the desert basins, their middle portions usually have the lowest annual precipitation, while their western and eastern portions have a much higher annual precipitation. An annual precipitation of 3.9 mm had been recorded in Toksun County of Xinjiang. The mean annual humidity is less than 60% on average in 80% of the total desert region nationwide, with those in Tarim, Alxa, and Qaidam being below 40%.

Table 13.4 Climatic parameters for certain deserts of China Region Tarim Basin Junggar Basin Eastern Xinjiang Qaidam Basin Hexi Corridor Alxa high plains Ordos Plateau Entire extent

MAP (mm) 73.7 173.7 68.9 61.4 104.0 117.0 251.8 290.3

MAT ( C) 10.1 5.2 7.8 3.4 7.4 8.1 6.3 3.4

AI 15.8 5.9 13.6 9.8 6.7 6.4 2.5 1.9

HI 3.7 11.6 3.9 4.6 5.9 6.4 15.2 21.9

MACT (10  C) 3944 3167 3591 1900 3144 3509 3013 2717

MTJ ( C) 7.8 15.8 11.5 11.5 9.4 10.2 11.4 17.2

MTJul ( C) 24.1 22.7 23.7 16.7 22.1 24.5 22.0 21.7

ND (d) 196 165 178 128 172 178 165 150

SD (h) 2826 2862 3180 3215 3131 3221 3081 3017

Abbreviations: MAP mean annual precipitation; MAT mean annual temperature; AI aridity index; HI humidity index; MACT mean annual cumulative temperature; MTJ mean temperature in January; MTJul mean temperature in July; ND number of days 10  C; SD sunshine duration (h)

13.3

Typical Deserts

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13.3.3 Soils Three zonal soil types are most closely associated with the typical desert vegetation, namely the gray desert soil, graybrown desert soil, and brown desert soil. The gray desert soil occurs in the transitional areas from the eastern edge of the temperate desert to the desert steppe. It is found mainly in the Hetao area (the Great Bend of the Yellow River) of Inner Mongolia, the northwestern corner of Ningxia, both sides of the Junggar Basin, the midsection of the Hexi Corridor, and the piedmont areas of the Qilian Mountains. Its overall area is approximately 4.59 million hm2, 56% of which occurs within Inner Mongolia. In these regions, mean annual temperatures range from 4 to 9  C; mean annual values of precipitation vary between 100 and 200 mm, which usually are 15–20-fold fewer than the annual evaporation rates. Its soil profile is composed usually of four layers, i.e., the soil crust layer, compact layer, gypsum- and salt-containing layer, and bedrock horizon, which are at depths of 1–5 cm, 5–15 cm, 15–100 cm, and below 100 cm, respectively. Gypsum and salts are aggregated most significantly below the 60 cm soil depth, with maximums occurring mostly at the range of 80–100 cm in the profile. The SOM content of this soil is much higher than that of most of the other desert soils, ranging from 5 to 15 g/ kg nationwide. Gypsum contents vary substantially, with those measured in Inner Mongolia being lower than 10 g/ kg, while those measured in Xinjiang being as high as 20–80 g/kg. Salt contents mostly are between 5 and 20 g/ kg, dominated by mixed ingredients of chloride, sulfate, and calcium bicarbonate. Several subtypes are distinguished, comprising the orthic, meadow, calcic, saline, and alkaline ones (Table 13.5). The gray-brown desert soil is the largest type of the desert soils, with a total area of some 30.72 million hm2. The associated climates are extremely dry, with the mean annual precipitation mostly being between 50 and 100 mm, and with the minimal mean of 17.8 mm observed in the Qaidam Basin. The vegetation it supports is composed primarily of xero- and super-xerophilous shrubs and dwarf hemi-shrubs, with a canopy coverage mostly being lower than 5%. The parent Table 13.5 Chemical properties of the gray desert soil of Inner Mongolia SL 0–6 6–29 29–60 60–115

TC 4.2 5.9 4.7 4.6

TN 0.23 0.33 0.29 0.31

TP 0.45 0.40 0.29 0.35

TK 20.3 19.0 18.8 18.6

pH 8.4–9.1 8.6–9.0 8.5–8.9

CaCO3 68.8 58.1 62.0 65.0

Eighteen sites on average. (Adapted from IMSSO 1994) Abbreviations: SL soil layer (cm); TC total carbon (g/kg); TN total nitrogen (g/kg); TP total phosphorus (g/kg); TK total potassium (g/kg)

materials are diluvial deposits of gravels, coarse skeletal slope deposits, and residuals, which are relatively rich in salts. The groundwater is deep underneath soil, imposing a little influence on the genesis of this soil. As previously elaborated, the formation of the gray-brown desert soil is characterized by enrichment in gravel, ferruginization of subsoil, superficial aggregation of limestone, and accumulation of soluble salts and gypsum (CNSSO 1998). Owing to the rare precipitation, leaching in the soil practically never has occurred. Therefore, CaCO3 produced by weathering accumulates degree by degree in the topsoil, which usually attains 45–200 g/kg in content and decreases rapidly with soil depth. Soluble salt contents generally are between 5 and 30 g/ kg, and those of gypsum average 80 g/kg, with a range of 100–400 g/kg occurring in heavily deposited soil layers. At some sites, the accumulation of nitrate is found at times, with a content of nitric nitrogen being as high as 150–900 mg/kg. The profile generally is 50 cm in depth, composed of, in a top-down sequence, the gravel-cohesive layer 2–3 cm thick, the porous crust layer 2–4 cm thick, the compact soil layer 3–10 cm thick, and the gypsum accumulation horizon 10–50 cm thick. Nutrient regimes of the soils in the various regions are listed in Table 13.6. Three subtypes of natural gray-brown desert soils are recognized, i.e., the orthic, gypsic, and alkalized ones. The orthic subtype is most typical of its type and is found mainly in northern Gansu and the northeastern corner of Qinghai, which assumes the largest proportion (66.5%) of the total area of the gray-brown desert soil. Its particle composition and chemical property parameters of this soil subtype sampled in Xinjiang are presented in Table 13.7. The brown desert soil has a total area of some 24.29 million hm2 nationwide, with about 93% found in Xinjiang, where it is vastly and continuously distributed in areas to the south of the Tianshan-Beishan line, west of the Jiayu Pass, and north of the Kunlun Mountains. The mean annual precipitation mostly is fewer than 50 mm, while the evaporation rate is between 2500 and 3000 mm. This soil is characterized by extremely weak biomass accumulation, absence of soil crusts, as well as significant surface accumulations of CaCO3, gypsum, and salts. Its soil profile consists of a gravel-cohesive layer 2–3 cm thick, a compact layer 2–10 cm thick, a gypsum and salt accumulation layer varying in thickness between 10 and 40 cm, and a bedrock horizon. This soil is highly skeletal, with gravels accounting for 20–50% of the total particles while clays usually making up no more than 15%. Four subtypes are recognized, the nutrient contents of which are compared in Table 13.8. In addition, the brown desert soil is also found in the eastern boundary areas between Gansu and Outer Mongolia, covering a total area of some 9.48 million hm2. The parent materials are quite rich in gypsum, and thus the gypsic accumulation is conspicuously found, with a thickness of

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Desert Rangeland Ecosystem

Table 13.6 Nutrient contents of topsoils collected from different regions of the gray-brown desert soil Item SOM (g/kg) TN (g/kg) TP (g/kg) TK (g/kg) AN (mg/kg) AP (mg/kg) AK (mg/kg)

WM 3.37 0.20 0.62 20.8 43.6 2.9 190.4

Xinjiang 4.3, n ¼ 45 0.29, n ¼ 45

IM 3.2, n ¼ 479 0.19, n ¼ 380

22.3, n ¼ 4 19, n ¼ 37

23.2, n ¼ 22 2.4, n ¼ 424 177, n ¼ 440

367, n ¼ 42

Gansu

0.66, n ¼ 135 21.1, n ¼ 62 62.5, n ¼ 76 5.5, n ¼ 90 193.2, n ¼ 128

Qinghai 4.5, n ¼ 36 0.18, n ¼ 36 0.48, n ¼ 36 20.8, n ¼ 36 28.0, n ¼ 34 2.6, n ¼ 34 135.0, n ¼ 34

Abbreviations: T total; A available; WM weighted mean nationwide; IM Inner Mongolia. (Adapted from CNSSO 1998)

Table 13.7 Particle composition (mm, %) and chemical property values (g/kg) of the orthic gray-brown desert soil Items >2 2–0.2 0.2–0.02 0.02–0.002