Wetland Habitats of North America: Ecology and Conservation Concerns 9780520951419

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W E T L A N D H A B I TATS O F N O R T H A M ER I CA

th e ste p h e n b echte l f u n d i m p r i nt i n ec o lo gy an d th e e nvi r o n m e nt

the Stephen Bechtel Fund has established this imprint to promote understanding and conservation of our natural environment.

Wetland Habitats of North America ECOLOGY AND CONSERVATION CONCERNS

Edited by DAROLD P. BATZER ANDREW H. BALDWIN

U NIVER SIT Y OF CALIFOR NIA PR ESS Berkeley Los Angeles London

The publisher gratefully acknowledges the generous contribution to this book provided by the Stephen Bechtel Fund.

University of California Press, one of the most distinguished

Library of Congress Cataloging-in-Publication Data

university presses in the United States, enriches lives around the world by advancing scholarship in the humanities, social sciences,

  Wetland habitats of North America : ecology and conservation

and natural sciences. Its activities are supported by the UC Press

concerns / edited by Darold P. Batzer and Andrew H. Baldwin.

Foundation and by philanthropic contributions from individuals

   p.  cm.

and institutions. For more information, visit www.ucpress.edu.

  ISBN 978-0-520-27164-7 (cloth : alk. paper)   1. Wetlands—North America.  2. Wetland ecology—North  

 

University of California Press

America.  3. Wetland conservation—North America.  I. Batzer,

Berkeley and Los Angeles, California

Darold P.  II. Baldwin, Andrew H.

 

QH102.W48  2012 University of California Press, Ltd.

577.68097—dc23

2011035545

 

London, England Manufactured in China © 2012 by The Regents of the University of California 19  18  17  16  15  14  13  12  10  9  8  7  6  5  4   3  2  1 The paper used in this publication meets the minimum requirements of ANSI/NISO Z39.48–1992 (R 1997) (Permanence of Paper). 8  

Cover photograph: Tidal freshwater marsh, Patuxent River, Anne Arundel County, Maryland. Photo by Andrew H. Baldwin.

This book is dedicated to Linda, Brant, and Ross (D. P. B.) and to Virginia, Paula, Catherine, and Elizabeth (A. H. B.).  

In memory of Charles C. Baldwin, Joan G. Ehrenfeld, and Robert L. Jefferies

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CONTENTS

CONTRIBUTORS  ix PREFACE  xiii

12. Beaver Wetlands  /  161 CAROL A. JOHNSTON

13. Great Lakes Coastal Marshes  /  173

1. Wetland Habitats of North America: An Introduction  /  1 ANDREW H. BALDWIN AND DAROLD P. BATZER

DOUGLAS A. WILCOX

14. Pocosins: Evergreen Shrub Bogs of the Southeast  /  189 CURTIS J. RICHARDSON

PART ONE

Coastal Wetlands

2. North Atlantic Coastal Tidal Wetlands  /  13 CATHLEEN WIGAND AND CHARLES T. ROMAN



3. Coastal Wetlands of Chesapeake Bay  /  29 ANDREW H. BALDWIN, PATRICK J. KANGAS, J. PATRICK MEGONIGAL, MATTHEW C. PERRY, AND DENNIS F. WHIGHAM



4. South Atlantic Tidal Wetlands  /  45 STEVEN C. PENNINGS, MERRYL ALBER, CLARK R. ALEXANDER, MELISSA BOOTH, ADRIAN BURD, WEI-JUN CAI, CHRISTOPHER CRAFT, CHESTER B. DEPRATTER, DANIELA DI IORIO, CHARLES S. HOPKINSON, SAMANTHA B.



DAROLD P. BATZER, FRANK DAY, AND STEPHEN W. GOLLADAY

17. The Florida Everglades  /  231 EVELYN E. GAISER, JOEL C. TREXLER, AND PAUL R. WETZEL

18. Floodplain Wetlands of the Southeastern Coastal Plain  /  253 SAMMY L. KING, LORETTA L. BATTAGLIA, CLIFF R. HUPP, RICHARD F. KEIM, AND B. GRAEME LOCKABY

19. Tropical Freshwater Swamps and Marshes  /  267 HUGO LÓPEZ ROSAS

5. Mississippi River Delta Wetlands  /  63

6. Wetlands of the Northern Gulf Coast  /  75 MARK S. PETERSON, KEVIN S. DILLON, AND JENNEKE M. VISSER

7. Neotropical Coastal Wetlands  /  89 KAREN L. MCKEE

8. Pacific Coast Tidal Wetlands  /  103 JOHN C. CALLAWAY, AMY B. BORDE, HEIDA L. DIEFENDERFER, V. THOMAS PARKER, JOHN M. RYBCZYK, AND RONALD M. THOM

PART TWO

Inland Wetlands

16. Southeastern Swamp Complexes  /  217

PATRICIA MORENO-CASASOLA, DULCE INFANTE MATA, AND

LORETTA L. BATTAGLIA, MARK S. WOODREY,



STEPHEN W. GOLLADAY

SILLIMAN, VICTOR THOMPSON, AND JOHN P. WARES

GARY P. SHAFFER, AND MARK W. HESTER



L. KATHERINE KIRKMAN, LORA L. SMITH, AND

JOYE, CHRISTOF D. MEILE, WILLARD S. MOORE, BRIAN

JENNEKE M. VISSER, JOHN W. DAY, JR., LORETTA L. BATTAGLIA,



15. Southestern Depressional Wetlands  /  203

9. Northern Peatlands  /  119 LINE ROCHEFORT, MARIA STRACK, MONIQUE POULIN, JONATHAN S. PRICE, MARTHA GRAF, ANDRÉ DESROCHERS, AND CLAUDE LAVOIE

20. Northern Great Plains Wetlands  /  283 SUSAN GALATOWITSCH

21. High Plains Playas  /  299 LOREN M. SMITH, DAVID A. HAUKOS, AND SCOTT T. MCMURRY

22. Western Mountain Wetlands  /  313 DAVID J. COOPER, RODNEY A. CHIMNER, AND DAVID M. MERRITT

23. Desert Spring Wetlands of the Great Basin  /  329 MARY JANE KELEHER AND DON SADA

24. Riparian Floodplain Wetlands of the Arid and Semiarid Southwest  /  343 JULIET C. STROMBERG, DOUGLAS C. ANDERSEN, AND MICHAEL L. SCOTT

25. Wetlands of the Central Valley of California and Klamath Basin  /  357 JOSEPH P. FLESKES

26. Freshwater Arctic Tundra Wetlands  /  371 LAURA GOUGH

10. Northeastern Seasonal Woodland Pools  /  135 ARAM J. K. CALHOUN, MEGAN K. GAHL, AND ROBERT F. BALDWIN

11. Northern Red Maple and Black Ash Swamps  /  149 JOAN EHRENFELD

INDEX  387 ADDITIONAL MATERIALS ARE AVAILABLE ONLINE AT WWW.UCPRESS.EDU/GO/WETLANDHABITATS.

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CONTRIBUTORS

merryl alber, Department of Marine Sciences, University of Georgia, Athens, GA 30602 Clark R. Alexander, Skidaway Institute of Oceanography, Savannah, GA 31411 Douglas C. Andersen, U.S. Geological Survey, Fort Collins Science Center, c/o U.S. Bureau of Reclamation, MS 86-68220, PO Box 25007, Denver, CO 80225 Andrew H. Baldwin, Department of Environmental Science and Technology, 1423 Animal Science Building, University of Maryland, College Park, MD 20742, [email protected] Robert F. Baldwin, Department of Forestry and Natural Resources, Lehotsky Hall, Clemson University, Clemson, SC 29631 Loretta L. Battaglia, Department of Plant Biology and Center for Ecology, Southern Illinois University Carbondale, Mailcode 6509, Carbondale, IL 62901, [email protected] Darold P. Batzer, Department of Entomology, University of Georgia, Athens, GA 30602, [email protected] Melissa Booth, University of Georgia Marine Institute, Sapelo Island, GA 31327

David J. Cooper, Department of Forest, Rangeland and Watershed Stewardship, Forestry Room 200, Colorado State University, Fort Collins, CO 80523, David.Cooper @warnercnr.colostate.edu Christopher Craft, School of Public and Environmental Affairs, Indiana University, Bloomington, IN 47405 Frank Day, Department of Biological Sciences, Old Dominion University, Norfolk, VA 23529 John W. Day, Jr., Coastal Ecology Institute, Louisiana State University, 2237 Energy Coast and Environment Building, Baton Rouge, LA 70803 Chester B. DePratter, South Carolina Institute of Archaeology and Anthropology, University of South Carolina, Columbia, SC 29208 André Desrochers, Peatland Ecology Research Group, Pavillon Paul-Comtois, Université Laval 2425, rue de l’Agriculture, Québec, Québec G1V 0A6, Canada Heida L. Diefenderfer, Pacific Northwest National Laboratory, Marine Sciences Laboratory, 1529 West Sequim Bay Road, Sequim, WA 98382

Amy B. Borde, Pacific Northwest National Laboratory, Marine Sciences Laboratory, 1529 West Sequim Bay Road, Sequim, WA 98382

Daniela Di Iorio, Department of Marine Sciences, University of Georgia, Athens, GA 30602

Adrian Burd, Department of Marine Sciences, University of Georgia, Athens, GA 30602

Kevin S. Dillon, Department of Coastal Sciences, University of Southern Mississippi, 703 East Beach Drive, Ocean Springs, MS 39564

Wei-Jun Cai, Department of Marine Sciences, University of Georgia, Athens, GA 30602 Aram J. K. Calhoun, Department of Wildlife Ecology, University of Maine, Orono, ME 04469, [email protected]

Joan Ehrenfeld, Department of Ecology, Evolution, and Natural Resources, SEBS, 14 College Farm Road, New Brunswick, NJ 08901

John C. Callaway, Department of Environmental Science, University of San Francisco, 2130 Fulton Street, San Francisco, CA 94117, [email protected]

Joseph P. Fleskes, U.S. Geological Survey–Western Ecological Research Center, 6924 Tremont Road, Dixon, CA 95620, joe_ [email protected]

Rodney A. Chimner, School of Forest Resources and Environmental Science, Michigan Tech University, 1400 Townsend Drive, Houghton, MI 49931

Megan K. Gahl, Department of Biology, Canadian Rivers Institute, University of New Brunswick, 100 Tucker Park Boulevard, Saint John, New Brunswick E2L 4L5, Canada

 

ix

Evelyn E. Gaiser, Department of Biological Sciences and Southeast Environmental Research Center, Florida International University, Miami, FL 33199, [email protected] Susan Galatowitsch, University of Minnesota, Department of Horticultural Science, 305 Alderman Hall, St. Paul, MN 55108, [email protected] Stephen W. Golladay, J. W. Jones Ecological Research Center, Route 2, Box 2324, Newton, GA 39870 Laura Gough, Department of Biology, University of Texas at Arlington, Arlington, TX 76019, [email protected] Martha Graf, Peatland Ecology Research Group, Pavillon Paul-Comtois, Université Laval 2425, rue de l’Agriculture, Québec, Québec G1V 0A6, Canada David A. Haukos, Kansas Cooperative Fish and Wildlife Research Unit, Kansas State University, Manhattan, KS 66506 Mark W. Hester, Department of Biology, University of Louisiana at Lafayette, PO Box 42451, Lafayette, LA 70504 Charles S. Hopkinson, Department of Marine Sciences, University of Georgia, Athens, GA 30602 Cliff R. Hupp, U.S. Geological Survey, 430 National Center, 12201 Sunrise Valley Drive, Reston, VA 20192 Dulce Infante Mata, Instituto de Ecología, A.C., Red de Ecología Funcional, Carretera Antigua a Coatepec no. 351, El Haya, Xalapa 91070, Veracruz, México

Scott T. McMurry, Department of Zoology, Oklahoma State University, Stillwater, OK 74078 J. Patrick Megonigal, Smithsonian Environmental Research Center, 647 Contees Wharf Road, Edgewater, MD 21037 Christof D. Meile, Department of Marine Sciences, University of Georgia, Athens, GA 30602 David M. Merritt, U.S. Forest Service Watershed, Fish, and Wildlife, and Colorado State University Natural Resource Ecology Laboratory, Natural Resources Research Center, 2150 Centre Avenue, Building A, Suite 368, Fort Collins, CO 80526 Willard S. Moore, Department of Earth and Ocean Sciences, University of South Carolina, Columbia, SC 29208 Patricia Moreno-Casasola, Instituto de Ecología, A.C., Red de Ecología Funcional, Carretera Antigua a Coatepec no. 351, El Haya, Xalapa 91070, Veracruz, México, patricia.moreno@ inecol.edu.mx V. Thomas Parker, Department of Biology, 449 Hensill Hall, 1600 Holloway Avenue, San Francisco State University, San Francisco, CA 94132 Steven C. Pennings, Department of Biology and Biochemistry, University of Houston, Houston, TX 77204, scpennin@ Central.UH.EDU Matthew C. Perry, U.S. Geological Survey, Patuxent Wildlife Research Center, 12100 Beech Forest Road, Laurel, MD 20708

Carol A. Johnston, Department of Biology and Microbiology, Box 2207B, South Dakota State University, Brookings, SD 57007–0896, [email protected]

Mark S. Peterson, Department of Coastal Sciences, University of Southern Mississippi, 703 East Beach Drive, Ocean Springs, MS 39564

Samantha B. Joye, Department of Marine Sciences, University of Georgia, Athens, GA 30602

Monique Poulin, Peatland Ecology Research Group, Pavillon Paul-Comtois, Université Laval 2425, rue de l’Agriculture, Québec, Québec G1V 0A6, Canada

 

Patrick J. Kangas, Department of Environmental Science and Technology, 1426 Animal Science Building, University of Maryland, College Park, MD 20742 Richard F. Keim, 227 School of Renewable Natural Resources, Louisiana State University Agricultural Center, Baton Rouge, LA 70803 Mary Jane Keleher, Salt Lake Community College, Biology Department, 4600 Redwood Road, Salt Lake City, UT 84130, [email protected] Sammy L. King, Louisiana Cooperative Fish and Wildlife Research Unit, U.S. Geological Survey, 124 School of Renewable Natural Resources, Baton Rouge, LA 70803, sking16@lsu .edu L. Katherine Kirkman, J. W. Jones Ecological Research Center, Route 2, Box 2324, Newton, GA 39870, kkirkman@ jonesctr.org

Jonathan S. Price, Peatland Ecology Research Group, Pavillon Paul-Comtois, Université Laval 2425, rue de l’Agriculture, Québec, Québec G1V 0A6, Canada Curtis J. Richardson, Wetland Center, Nicholas School of the Environment and Earth Science, Duke University, Durham, NC 27708, [email protected] Line Rochefort, Peatland Ecology Research Group, Pavillon Paul-Comtois, Université Laval 2425, rue de l’Agriculture, Québec, Québec G1V 0A6, Canada, Line.Rochefort@fsaa .ulaval.ca Charles T. Roman, National Park Service, North Atlantic Coast Cooperative Ecosystem Studies Unit, University of Rhode Island, Narragansett, RI 02882 John M. Rybczyk, Department of Environmental Science, ES437, Huxley College, Western Washington University, 516 High Street, Bellingham, WA 98225

Claude Lavoie, Peatland Ecology Research Group, Pavillon Paul-Comtois, Université Laval 2425, rue de l’Agriculture, Québec, Québec G1V 0A6, Canada

Don Sada, Desert Research Institute, Division of Hydrological Sciences, 2215 Raggio Parkway, Reno, NV 89512

B. Graeme Lockaby, School of Forestry and Wildlife Sciences, Auburn University, Auburn, AL 36849

Michael L. Scott, U.S. Geological Survey, Fort Collins Science Center, Fort Collins, CO 80526

Hugo López Rosas, Instituto de Genética, Universidad del Mar, Puerto Escondido 71980, Oaxaca, México

Gary P. Shaffer, Department of Biological Sciences, 405 Biology Building, Southeastern Louisiana University, Box 10736, Hammond, LA 70402

Karen L. McKee, U.S. Geological Survey, National Wetlands Research Center, 700 Cajundome Boulevard, Lafayette, LA 70506, [email protected]

x  Con tributors

Brian R. Silliman, Department of Biology, University of Florida, Gainesville, FL 32611

Lora L. Smith, J. W. Jones Ecological Research Center, Route 2, Box 2324, Newton, GA 39870

John P. Wares, Department of Genetics, University of Georgia, Athens, GA 30602

Loren M. Smith, Department of Zoology, Oklahoma State University, Stillwater, OK 74078, [email protected]

Paul R. Wetzel, Center for the Environment, Ecological Design and Sustainability, Smith College, Northampton, MA 01063

Maria Strack, Peatland Ecology Research Group, Pavillon Paul-Comtois, Université Laval 2425, rue de l’Agriculture, Québec, Québec G1V 0A6, Canada Juliet C. Stromberg, School of Life Sciences, Arizona State University, Tempe, AZ 85287–4501,[email protected]  

Ronald M. Thom, Pacific Northwest National Laboratory, Marine Sciences Laboratory, 1529 West Sequim Bay Road, Sequim, WA 98382 Victor Thompson, Department of Anthropology, The Ohio State University, Columbus, OH 43210 Joel C. Trexler, Department of Biological Science, Florida International University, 3000 NE 151st Street, Miami, FL 33199 Jenneke M. Visser, Institute for Coastal Ecology and Engineering and School of Geoscience, University of Louisiana at Lafayette, PO Box 44650, Lafayette, LA 70504, jvisser@ louisiana.edu

Dennis F. Whigham, Smithsonian Environmental Research Center, 647 Contees Wharf Road, Edgewater, MD 21037 Cathleen Wigand, U.S. Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Lab, Atlantic Ecology Division, Narragansett, RI 02882, wigand.cathleen@ epa.gov Douglas A. Wilcox, Department of Environmental Science and Biology, The College at Brockport, State University of New York, 350 New Campus Drive, Brockport, NY 14420, [email protected] Mark S. Woodrey, Coastal Research and Extension Center, Mississippi State University, 1815 Popps Ferry Road, Biloxi, MS 39532

Con tr ibutor s   xi

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PREFACE

Wetlands are a prominent landscape feature throughout the North American continent. While the general characteristics of wetlands are well understood, there has not been a systematic assessment of the scientific literature on the ecology of different wetland habitat types in various parts of North America, or a compendium of the threats to their conservation. We were inspired by the robust and incredibly detailed series “Community Profiles” and “Estuarine Profiles,” published by the U.S. Fish and Wildlife Service primarily in the 1980s, with a few in the early 1990s. There are 56 of these profiles, each of which focuses on a particular wetland type or estuary in a specific part of the USA. We have adopted a similar geographic and habitat approach in this book, in which experts familiar with wetlands from many parts of North America provide analyses of current and classic literature on studies collected in, or directly relevant to, their particular region of study. In editing this book, we have kept the needs of a fairly broad audience in mind: students, scientists, engineers, environmental managers, policymakers, and the general public. Our goal is to provide reviews of recent, scientifically rigorous literature directly relevant to understanding, managing, protecting, and restoring wetland ecosystems in various regions of North America. This book should be useful as a textbook in graduate and undergraduate courses in ecology and environ-

mental science programs, but also should be a valuable reference for researchers in academic and governmental institutions. We hope it will foster improved understanding of variation in ecological processes and threats to conservation across the regions of North America, and that it will point the way toward future research and collaborations. The habitat approach used here also lends itself to application in managing and restoring different types of wetlands in a wide range of geomorphic and hydrologic settings. The broad geographic coverage and habitat format are also well suited to developing environmental policy relevant to wetland regulation over large areas. And, finally, the text and layout of the chapters, while grounded in rigorous science, are accessible to anyone interested in learning more about the great diversity and variability of the types of wetlands in their own region or in other parts of North America. We extend our deepest thanks and appreciation to the contributors to this book and to our anonymous reviewers, who volunteered their time, knowledge, and enthusiasm toward the creation of this book, and to our families, who put up with our late nights and celebrated our successes. Andy Baldwin Darold Batzer

xiii

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CHAP TER 1

Wetland Habitats of North America An Introduction ANDREW H. BALDWIN and DAROLD P. BATZER

The goal of this book is to summarize recent literature and current perspectives on the ecology of wetland habitats of the North American continent and primary concerns regarding their conservation. All wetlands, by definition, share certain characteristics, notably the seasonal or permanent saturation or inundation of soils. This waterlogging of soils and the presence of standing water impose ecological constraints on organisms and a geomorphological environment very different from those of nonwetland ecosystems. Beyond the broad umbrella of inundation and soil saturation, however, wetlands differ dramatically between and within climatic and geomorphic zones due to myriad interacting physical, chemical, and biological processes. Environmental studies or restoration projects conducted in one type of wetland in one part of North America may have outcomes that are broadly or narrowly applicable to wetlands elsewhere. This creates a dilemma for wetland scientists, students, managers, and policymakers, who must identify research projects, implement management or restoration, and develop environmental policy based on limited information. In this book, we chose a habitat and geographical approach to highlight differences among the most important ecological characteristics and threats to the major types of North American wetlands. This book is a companion volume to Ecology of Freshwater and Estuarine Wetlands (Batzer and Sharitz 2006), which addresses ecosystem processes and structural attributes of wetlands in general, across many types of wetlands. Other recent books that provide general information include Wetlands (Mitsch and Gosselink 2007), Wetland Ecology: Principles and Conservation (Keddy 2010), and The Biology of Freshwater Wetlands (van der Valk 2006). The earlier edition of Wetlands (Mitsch and Gosselink 2000) included seven chapters on individual coastal and inland wetland habitats, which were updated and expanded in a separate volume, Wetland Ecosystems (Mitsch, Gosselink, et al. 2009). Individual habitats were also treated in Coastal Wetlands: An Integrated Ecosystem Approach (Perillo, Wolanski, et al. 2009) and in Ecology of Tidal Freshwater Forested Wetlands of the Southeastern United States (Conner, Doyle, et al. 2007). Our book differs from these

works in that it takes a systematic, geographic approach to capture a similar set of ecosystem characteristics and conservation concerns for all major wetland habitat types within different regions of North America. In this, our approach is similar to the “Community Profiles” series published by the U.S. Fish and Wildlife Service. The wetlands of North America are wonderfully diverse. They range from the tropics to the Arctic and are widespread in Canada, the United States, Mexico, and Central America. The chapters in this book are written by experts with deep knowledge and experience in most of the major types of wetlands in different regions of North America (Fig. 1.1). Our coverage is complete, with one important exception: Arctic coastal wetlands. Robert Jefferies, a leader in this area, had agreed to author a chapter on this topic, but, to our great sadness, he passed away before he could do so. We refer the reader to a chapter he coauthored in another book (Martini, Jefferies, et al. 2009). To provide a framework, we asked authors to address several main aspects of the wetlands in their region:

. Geology, hydrology, and biogeochemistry . Plant communities . Animal communities . Key ecological processes and controls . Conservation concerns or threats To reduce repetition between chapters, we specifically asked authors not to include general information on wetlands, but to focus only on studies or information collected in their region. Chapters on coastal wetlands are included in part I of the book. They are grouped separately from nontidal wetlands because of the overriding influence of tidal hydrology on their structure and functioning. Inland wetlands are grouped in part II. There are many more habitat types of inland wetlands than coastal wetlands due to great variation in relative inputs of precipitation, surface water, and groundwater, as well as their greater surface area and richness of plant and animal taxa. Wetlands of the temperate zone have received more scientific attention than those of the tropics and Arctic, and hence we 1

170°E

180°

170°W

160°W

150°W 140°W

120°W

100°W

80°W 70°W 60°W 50°W

40°W

30°W

20°W

10°W

26

50°N

60°N

22 26 50°N 40°N

22

20

30°N

8 25 23 24

20°N

22

9 12 13 10 11

7

110°W

10 11 2 12

19 7

0°

120°W

40°N

14 3 15 21 18 4 15 16 6 6 5 7 7 19

10°N

130°W

9

100°W

90°W

30°N

17

20°N

7

7

10°N

80°W

70°W

FIG. 1.1. Location of wetlands covered in this book within the North American continent. Numbers

correspond to the chapter covering those wetlands. Coastal wetland chapters have numbers in the ocean adjacent to their position on the coast. Map prepared by A. H. Baldwin.

include more chapters on those wetlands, which primarily occur in the USA. The vast areas of wetlands in northern North America and biologically rich tropical wetlands are nonetheless important and ecologically interesting ecosystems deserving of greater study. In this introductory chapter, we summarize important differences and similarities between wetland habitats in different regions of North America, separating discussion of coastal and inland wetlands and focusing on key ecological processes and conservation concerns. To assess the generality of processes and concerns, as well as their regional importance, we list their occurrence in each chapter in Tables 1.1 (coastal wetlands) and 1.2 (inland wetlands). This approach does not mean that some processes are not important in regions elsewhere, but may reflect a lack of literature on the topic. Differences among the relative importance of dominant or unique plant or animal taxa are also discussed here.

Coastal Wetlands Key Ecological Processes and Controls The development of coastal wetlands is fundamentally a result of geomorphology and climate, which together create hydrologic characteristics that exert an overriding influence on wetland ecosystem structure and function. All authors of coastal chapters in this book explicitly or implicitly identify these factors as fundamental controls on wetland ecosystems (Table 1.1a). The hydrology of coastal wetlands differs considerably 2  IN TRODUCTION

from that of inland wetlands in being dominated by tides and, to a lesser extent, surface water inflows (which control salinity, nutrient supply, and sediment deposition). Groundwater and precipitation are rarely mentioned in the coastal chapters. Because coastal wetlands are located in the depositional zone of rivers in estuaries, it is not surprising that sedimentation and salinity are also uniformly recognized as important. However, several biotic processes are mentioned in all of the coastal chapters, including productivity, peat accumulation, predation, outwelling, and vegetation zonation, which are discussed in more detail in this section. High primary productivity, coupled with slow decomposition rates due to anaerobic conditions, favors the accumulation of peat in soils, providing a mechanism important for the maintenance of wetland surface elevation relative to sea level. Primary productivity and peat accumulation are highlighted in all of the coastal chapters, and decomposition and anaerobiosis are featured in a majority of them (Table 1.1a). Elevation and salinity gradients within individual wetlands and across estuaries lead to horizontal zonation of emergent and submergent plants, another ubiquitous topic in the coastal chapters. Stress-tolerant species occur where salinity or depth and duration of inundation are greater (and hypoxia more pronounced), such as the lower elevations of salt marshes, but studies have demonstrated that these species are often poor competitors in fresher or higher-elevation sites, such as the higher elevations of tidal freshwater wetlands. Under stressful conditions, one species may facilitate the growth of others by, for example, aerating the soil or shading to reduce salinity. Competition and facilitation are recognized as important pro-

table 1.1 A. Key ecological processes and controls B. Conservation concerns highlighted by authors of seven chapters addressing coastal wetlands Processes/controls and concerns are sorted first in decreasing order of the number of chapters in which they are noted and then alphabetically. A triangle (▲) indicates the process or concern is discussed in a chapter.

Chapter number No. of chapters

2

3

4

5

6

7

8

Climatic variation (El Niño, drought, latitude, elevation)

7

▲

▲

▲

▲

▲

▲

▲

Geomorphic variation (topography, soils, glaciation)

7

▲

▲

▲

▲

▲

▲

▲

Hydrologic variation (hydroperiod, flows, groundwater inputs, evapotranspiration)

7

▲

▲

▲

▲

▲

▲

▲

Nutrient supplies (phosphorus/nitrogen limitation and cycling)

7

▲

▲

▲

▲

▲

▲

▲

Outwelling and external trophic support

7

▲

▲

▲

▲

▲

▲

▲

Peat accumulation

7

▲

▲

▲

▲

▲

▲

▲

Predation

7

▲

▲

▲

▲

▲

▲

▲

Primary productivity

7

▲

▲

▲

▲

▲

▲

▲

Salinity/conductivity

7

▲

▲

▲

▲

▲

▲

▲

Sedimentation

7

▲

▲

▲

▲

▲

▲

▲

Vegetation gradients and zonation

7

▲

▲

▲

▲

▲

▲

▲

Decomposition

6

▲

▲

▲

▲

▲

▲

Plant-animal interactions (herbivory, detritivory, plants/wood as habitat)

6

▲

▲

▲

▲

▲

▲

Anoxia/oxygen

5

▲

▲

▲

▲

▲

Seed dispersal/rain, seed predation, seed banks, and seedling recruitment

5

▲

▲

▲

▲

Competition (food, light, nutrients)

4

▲

▲

▲

Habitat connectivity (isolation, upland-wetland interaction, patchiness)

4

▲

Storms (hurricanes, floods)

4

Endemism

3

Facilitation

3

Fire

3

▲

Keystone species (ecosystem engineers, beavers)

3

▲

Mutualism (N-fixation, mycorrhizae)

3

pH (acidity, alkalinity)

2

a. key ecological processes and controls

▲

▲

▲

▲

▲

▲

▲

▲

▲

▲

▲

▲

▲

▲ ▲

▲

▲

▲

▲

▲

▲

▲

▲

▲

(continued)

table 1.1 (continued)

Chapter number No. of chapters

2

3

4

5

6

7

8

Sea-level rise

7

▲

▲

▲

▲

▲

▲

▲

Restoration/mitigation practices

6

▲

▲

▲

▲

▲

▲

Eutrophication (point and nonpoint sources)

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Population increase

3

Subsidence

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Sudden die-back

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Elevated CO2

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2

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cesses in about half the coastal chapters. Some salt-marsh soils become acidic when drained (acid-sulfate soils, mentioned in two coastal chapters), but coastal wetland soils are generally pH-circumneutral. High rates of primary productivity and, in many wetlands, structural, spatial, and species diversity of plants, result in high rates of secondary production. Coastal wetlands support estuarine food webs not only by providing in situ habitat and food sources, but also by exporting or “outwelling” organic matter to estuaries, forming an important foundation of coastal food webs that is emphasized in all of the coastal chapters. Coastal wetlands often serve as nurseries for larval and juvenile stages of aquatic organisms, providing refuge from predation, an ecological process mentioned in all of the coastal chapters. Plantanimal interactions are also a major process in most coastal wetlands; herbivory is most frequently mentioned, both for its role in food-web support and as a disturbance process affecting plant community dynamics. Seed-related processes, including dispersal, predation, seed banks, and seedling recruitment, mentioned in a majority of the coastal chapters, are often important to the regeneration of plant communities following disturbance and are critical to diversity maintenance in wetlands containing a large proportion of annual species, such as tidal freshwater marshes. The particular importance of storms and hurricanes is recognized for those regions experiencing regular major hurricanes, i.e., the southeastern U.S. coasts and parts of the Neotropics. Some plants and animals function as ecosystem engineers, altering the geomorphology and hydrology of coastal

4  IN TRODUCTION

wetlands; examples include beavers, crabs, and dominant clonal plants. Thus, the vegetation of coastal wetlands is dynamic, in large part due to continued natural disturbance, seed and seedling-recruitment processes, and competitive interactions.

Conservation Concerns It is not a surprise that sea-level rise is identified as a major threat to coastal wetlands in all parts of North America (Table 1.1b). Increases in the rate of eustatic sea-level rise, coupled with land subsidence in many regions, will challenge the capacity of coastal wetlands to keep pace with rising sea levels. Eutrophication due to inputs of nitrogen or phosphorus from point and nonpoint sources is also identified as important in all regions except the Pacific coast. Excess nutrients are important in shifting plant species composition and have been implicated as a potential factor in marsh die-back. Many wetlands have been hydrologically altered since European colonization, but despite environmental statutes regulating activities in wetlands, hydrologic alterations continue to threaten coastal wetlands in many regions of North America. Notably, these are not mentioned as being of overriding importance for south Atlantic wetlands, which are relatively unimpacted physically relative to other parts of the North American coast (except for widespread historic conversion of tidal freshwater wetlands to rice fields), or for Pacific coast wetlands, where the vast majority of coastal wetlands historically were

lost due to diking, but which are currently closely protected and restoration efforts are ongoing (Table 1.1b). Neotropical coastal wetlands, in contrast, were primarily used for sustainable harvest of vegetation and animal products until recent decades, when many mangrove forests have been converted to aquaculture ponds or tourist resorts. Nonnative or invasive species of plants or animals are also identified as a major conservation concern in a majority of coastal wetland chapters (Table 1.1b). Exceptions are the south Atlantic coastal wetlands and the Neotropics. South Atlantic wetlands may not face the invasive species problems of other regions due to lower ongoing physical alteration of coastal wetlands, perhaps due to lower population densities. In the Neotropics, temperate-zone plants and animals may not be able to tolerate elevated temperatures or to compete with tropical plants, reducing their threat to tropical ecosystems. In addition to causing increases in eustatic sea levels, changes in precipitation and temperature may impact wetlands in several ways and are mentioned in a majority of the coastal chapters. Lower precipitation may result in salinity increases in some regions where flow of freshwater to the coast is already insufficient or decreasing due to human alteration of hydrology, for example in the Pacific coast and south Atlantic watersheds. Similarly, climate change may cause widespread drought, a likely factor in die-back of coastal wetlands. Higher temperatures will differentially affect the growth of plant and animal species, as well as speed up processes such as decomposition that are fundamental to wetland ecosystem function. Increases in atmospheric CO2 (mentioned in only two chapters but likely to be important in all wetlands) are not only a cause of climate change, but also will alter plant community dynamics and potentially other ecosystem processes. Increasing human population density (identified in three coastal chapters) continues to threaten coastal wetlands via watershed development, land-use changes, harvesting of plant and animal resources, and further hydrologic alteration. These and other conservation concerns are related and linked in complex ways that require novel research approaches to untangle. Manipulative experiments that examine multiple processes together can provide insights into how factors such as CO2, nutrients, salinity, and temperature interact. Such experiments, coupled with observational studies and system modeling, can help us progress toward greater understanding and better prediction of how human activities are affecting coastal wetlands. However, the chapters in this book highlight that coastal wetland research must be multidisciplinary so that interactions between hydrology, climate, geomorphology, biogeochemistry, and organisms can be explored.

Inland Wetlands Key Ecological Processes and Controls As for coastal systems, hydrologic variation is identified as an important control on ecology by every author addressing inland wetlands (Table 1.2a). Given that inland wetlands can be fed by various sources of water (precipitation, groundwater, riverine flows), and that water budgets can vary greatly— either spatially among and within wetlands, or temporally among and within seasons, years, and decades — the importance given to hydrology is to be expected. Geomorphic and climatic variation are also identified as being important con 

 

trols by most authors, primarily because these are the factors that most influence the hydrology of inland wetlands. The chemical nature of the water, including nutrient levels (phosphorus and, to a lesser extent, nitrogen), pH, oxygen level, and salinity (especially in western wetlands), is also considered important. It is clear from Table 1.2a that the abiotic template dictated by the physico-chemical conditions of water is considered the major control on the ecology of inland wetlands. However, biotic interactions in inland wetlands are also considered important influences by most authors (Table 1.2a). Bottom-up controls are most frequently discussed. Nutrient limitation on plants from P and N, as well as competition for light and space, are common themes. Mutualism, especially in relation to nitrogen fixation by plants/microbes, is discussed in five chapters. Plants as food (herbivory or detritivory) or as habitat are considered crucial bottom-up controls on wetland animals by most authors. Top-down control from predation, either on other animals or on plants, is identified as an important control by about half of the authors of inland wetland chapters. Control of wetlands by keystone animal species is another important top-down impact, with beavers being by far the most influential animal. The impact of disturbance is a third general theme developed by authors of inland wetland chapters. Fire is identified as an important control in half of the chapters, particularly those focusing on the southeastern USA. Storms (primarily hurricanes in the Southeast and the tropics) floods, and droughts are other important disturbances. With the general importance of disturbance in inland wetlands, successional processes are identified as important controls by half of the authors. Landscape features as controls on inland wetlands is the final major theme developed by authors. As mentioned, geomorphic variation is considered a crucial impact on wetlands by most authors, and besides the impacts on hydrology, direct impacts of soils and topography are often identified as being important. Habitat connectivity across landscapes (e.g., isolation or patchiness) and interactions between uplands and embedded wetlands is a major theme, particularly for depressional habitats.

Conservation Concerns Since hydrology is considered the major ecological control on inland wetlands, it follows that any impacts on water budgets for wetlands are of particular concern (see Table 1.2b). Many of the authors of inland wetland chapters highlight threats from climate change, primarily because of concerns about potential hydroperiod alteration. Other concerns included under the umbrella of hydrology are impacts of flow regulation of rivers by dams and levees on riparian floodplain wetlands, impacts of groundwater pumping on assorted wetlands, and continued concern about any management that drains wetlands. While most author concern focuses on the threats posed by making wetlands drier, some chapters point out that factors that increase hydroperiods also need to be considered. For northeastern seasonal wetlands (see chapter 10), the authors point out that past mitigation efforts that have focused on developing long-hydroperiod ponds may actually pose a threat to seasonal wetland pools, as important functions associated with seasonal flooding are not being replaced. The theme of restoration is developed by several authors, again with the overriding theme focusing on restoration of natural hydrology.

IN TRODUCTION  5

table 1.2 A. Key ecological controls B. Conservation concerns as highlighted by authors of 18 chapters addressing inland wetlands of North America Processes/controls and concerns are sorted first in decreasing order of number of chapters in which they are noted and then alphabetically. A triangle (▲) indicates the process or concern was discussed in a chapter.

Chapter number No. of chapters

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Keystone species (ecosystem engineers, beavers)

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Primary productivity

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Peat accumulation

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Authors writing about conservation of inland wetlands focus on another major theme: biodiversity issues, primarily threatened or endangered species. Because many inland wetlands exist as isolated patches on the landscape, it is not surprising that endemic species, or at least species that occur across a restricted area, can be common. As these habitats are destroyed or degraded, resident species may become threatened. Because wetlands support biota unique from that of uplands, the value of embedded wetlands in buttressing overall regional diversity is frequently mentioned. Several authors point out that conIN TRODUCTION

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nectivity among wetland patches and between wetlands and surrounding uplands all need to be considered when assessing the integrity of overall wetland systems. A group of conservation threats to inland wetlands receives a similar level of attention from authors. Agriculture and water pollution have long been associated with the decline of inland wetlands, and both themes are still highlighted by the authors of this book. However, threats from urbanization and other development, and from climate change, are now receiving a similar level of focus. The threat from invasive species, particu-

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larly plants, is another pervasive theme (similar to coastal wetlands). Threats from livestock grazing are mentioned by nearly every author addressing western North American habitats. Because many “isolated” inland wetlands have recently lost legal protections from the U.S. government (e.g., Downing, Winer, et al. 2003), concern over wetland regulation in the USA is another important theme for many authors. However, concerns are not limited to recent statutory changes; instead a general angst exists about the adequacy of current laws protecting inland wetlands. Several authors express concerns over

the effectiveness of wetland monitoring programs, and also about declining appreciation of wetland virtues among the general public.

Conclusions This synthesis suggests some interesting ecological differences between coastal and inland wetlands. To some extent, this reflects the perspectives of the researchers working in each IN TRODUCTION  7

table 1.2 (continued)

Chapter number No. of chapters

9

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17

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12

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Threats from agriculture

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Water-quality issues (pollution, eutrophication)

9

Regulatory issues

7

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6

Connectivity issues (habitat fragmentation, upland-wetland interaction)

5

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Mining impacts (peat mining, gas/oil extraction)

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note: Only those processes or concerns addressed in at least four chapters are listed. If a specific topic is not highlighted for a specific habitat type, readers should not assume a lack of relevance, but simply that authors do not prioritize the topic in their review. Chapter numbers refer to 9. northern peatlands, 10. northeastern seasonal woodland pools, 11. northern red maple and black ash swamps, 12. beaver wetlands, 13. Great Lakes coastal marshes, 14. pocosins, 15. southeastern depressional wetlands, 16. southeastern swamp complexes, 17. Florida Everglades, 18. floodplain wetlands of the southeastern Coastal Plain, 19. tropical freshwater swamps and marshes, 20. northern Great Plains wetlands, 21. High Plains playas, 22. western mountain wetlands, 23. desert spring wetlands of the Great Basin, 24. riparian floodplain wetlands of the arid and semiarid Southwest, 25. wetlands of the Central Valley of California and Klamath Basin, and 26. freshwater Arctic tundra wetlands.

type of wetland, but ecological controls are probably unique in many ways. In general, abiotic factors, hydrology, geomorphic variation, and climate are identified as important controls in most inland chapters. Only two biotic processes or controls, nutrient supplies and plant-animal interactions, are featured in more than half of these chapters. Similar abiotic processes and the additional abiotic factors of salinity and sedimentation are recognized in all coastal wetlands chapters. However, biotic controls and processes are mentioned more frequently in coastal than in inland wetlands discussions. In particular, outwelling and trophic support, primary production, plantanimal interactions, decomposition, seed and seedling processes, competition, and habitat connectivity all feature in more than half of the coastal chapters. This difference in the relative importance of biotic versus abiotic ecological controls and processes may reflect the highly variable nature of hydrology in inland wetlands as compared to the relatively constant hydrologic regime of tides in coastal habitats. Given the more stable environment of coastal habitats, biotic interaction may be permitted to become particularly influential. Biotic interaction is likely also important in inland wetlands, but outcomes 8  IN TRODUCTION

may be hard to predict because the abiotic foundation is constantly changing. In coastal wetlands, the trophic connection between the wetlands and the open waters of the ocean through outwelling is considered one of the most important ecological controls or processes. Except perhaps in Great Lakes and floodplain wetlands, this kind of relationship does not exist in inland wetlands. On the other hand, because inland wetlands are often embedded in uplands, the interaction between wetlands and surrounding landscapes is frequently highlighted by authors addressing those habitats. Despite some differences in ecological interactions, perceived threats to both coastal and inland wetlands are remarkably similar. In all wetlands, concerns about human-induced hydrologic change (whether from development or climate change) seem paramount. Climate change, invasive species, and land-use changes are clearly among the most serious threats to the persistence of all wetlands. Regulatory policy that promotes conservation and sound management needs to be strengthened for all wetlands, and wetland-restoration practices need to be improved overall. These actions can mod-

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erate the effects of human population growth and activities on wetlands so that their ecological and socioeconomic functions and benefits can be maintained.

References Batzer DP, Sharitz RR, editors. 2006. Ecology of freshwater and estuarine wetlands. Berkeley: University of California Press. Conner WH, Doyle TW, Krauss KW, editors. 2007. Ecology of tidal freshwater forested wetlands of the southeastern United States. Dordrecht, The Netherlands: Springer. Downing DM, Winer C, Wood LD. 2003. Navigating through the Clean Water Act jurisdiction: a legal review. Wetlands 23:475–93.  

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Keddy PA. 2010. Wetland ecology: principles and conservation, 2nd ed. Cambridge: Cambridge University Press. Martini IP, Jeffries RL, et al. 2009. Polar coastal wetlands: development, structure, and land use. In Coastal wetlands: an integrated ecosystem approach, Perillo GME, Wolanski E, et al., editors. Amsterdam: Elsevier, pp. 119–55. Mitsch WJ, Gosselink JG. 2000. Wetlands, 3rd ed. New York: Wiley. Mitsch WJ, Gosselink JG. 2007. Wetlands, 4th ed. New York: Wiley. Mitsch WJ, Gosselink JG, et al. 2009. Wetland ecosystems. New York: Wiley. Perillo GME, Wolanski E, et al. 2009. Coastal wetlands: an integrated ecosystem approach. Amsterdam: Elsevier. van der Valk AG 2006. The biology of freshwater wetlands. Oxford: Oxford University Press.  

IN TRODUCTION  9

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PART I

COASTAL WETLANDS

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CHAP TER 2

North Atlantic Coastal Tidal Wetlands CATHLEEN WIGAND and CHARLES T. ROMAN

North Atlantic tidal wetlands are found behind barrier islands and sand spits, in sheltered bays, and throughout the region’s drowned-river valley estuaries, areas protected from direct wave action of the sea. They are primarily driven and sustained by the rise and fall of tides and bounded on the land side by the high water of the monthly spring tide cycle. Tidal wetlands include freshwater, brackish-water, and salt-marsh ecosystems and within the North Atlantic region can collectively be termed coastal wetlands. Coastal wetlands provide numerous ecosystem services, including fish, shellfish, and wildlife habitat; flood abatement and erosion control; water quality maintenance; and carbon sequestration (e.g., Odum, Smith, et al. 1984; Rabenhorst 1995; Teal and Howes 2000; Millenium Ecosystem Assessment 2005). With a worldwide estimate of 75% of the human population living in coastal regions (Emeis, Benoit, et al. 2001), coastal tidal wetlands are located in areas of intense commercial and residential activities. Urbanization is particularly relevant within the northeastern U.S., with coastal wetlands subjected to extensive physical alterations to the landscape, introduction of nonnative species, nitrogen (N) overenrichment, contaminants, and other stresses (Fig. 2.1) (Tiner 2005; Bertness, Ewanchuk, et al. 2002; Bertness, Silliman, et al. 2009; Gedan, Silliman, et al. 2009; Crain, Gedan, et al. 2009). Conservation efforts are required to restore and sustain the structure and function of North Atlantic coastal wetlands and associated ecosystem services (Fig. 2.1) (Gedan, Silliman, et al. 2009; Bertness, Silliman, et al. 2009). The North Atlantic coast can be divided into three regions with differing geomorphology: the Gulf of Maine region, including the Bay of Fundy; the coast from Cape Cod to the Hudson River; and the New Jersey Atlantic coast and Delaware Bay. In the Gulf of Maine region, the tidal range is large, especially in the Bay of Fundy (4+ m), leading to wetlands only in protected areas with considerable depths of deposited sediments. River and tidal erosion is high in the soft rocks of the Bay of Fundy area, producing an abundance of reddish silt. Throughout the remainder of the Gulf of Maine, salt marshes are built mainly on marine sediments and wetland peat, and there is less transport of sediment from the hard-rock watersheds. Fringing wetlands (narrow in width and small in size) are present along the Gulf of Maine coast (Morgan, Burdick, et al. 2009), although broad expanses of coastal wetlands

also exist (e.g., Scarborough Marsh, Maine; Great Marsh, Massachusetts). Coastal wetlands along the southern New England shore, including Cape Cod and southern Massachusetts, Rhode Island, Connecticut, and Long Island, also have extensive wetland peat accumulations and are often characterized by sandy to hard-rock watersheds. From New Jersey south, including Delaware Bay, individual tidal wetlands are more extensive than along the glaciated coast to the north (Teal and Teal 1969; Roman, Jaworski, et al. 2000). The size of individual salt marshes averages about 27 ha in Delaware Bay, and they are about 5 times greater in size than salt marshes farther north along the coast (Table 2.1). Using the U.S. Fish and Wildlife National Wetland Inventory (NWI) data for the northeastern U.S. states and taking into account estuarine intertidal emergent (i.e., salt marshes), estuarine intertidal scrub-shrub, and riverine tidal emergent (i.e., freshwater and brackish tidal marshes), there are about 159,131 ha of coastal wetlands from Maine to Delaware Bay (Table 2.1). Wetlands of the New Jersey and Delaware coasts of the Delaware Bay Estuary account for 38% of this total area. Jacobson, Jacobson, et al. (1987) estimated the areal extent of Maine coastal tidal marshes as 7,890 ha using planimetry studies and Maine Geological Survey coastal maps, and their estimate is similar to the estimate of 8,723 ha based on NWI data of estuarine intertidal emergent wetlands (Table 2.1). The areal extent (82,578 ha) of the coastal tidal wetlands in the state of New Jersey is the largest among the northeastern U.S. states. Extensive back-barrier salt marshes occur along the New Jersey Atlantic coast to Cape May, with extensive tidal wetlands, ranging from salt to freshwater tidal, along the New Jersey, Delaware, and Pennsylvania shores of the Delaware Bay and River (Chapman 1960; Daiber and Roman 1988). The Delaware Bay wetlands consist of 59,515 ha of salt marsh, 457 ha of scrub-shrub marsh, and 334 ha of freshwater and brackish tidal marshes among the states of New Jersey, Delaware, and Pennsylvania. About 54% of the Delaware Bay wetlands are in New Jersey and 46% in Delaware. In the northeastern U.S., there is a wide range of development pressure and land-use history, with some watersheds exposed to almost three centuries of intense urbanization (e.g., the lower Hudson River), while others have endured less development 13

Minimize, Mitigate, and Repair

Anthropogenic and Natural Stressors Affecting North Atlantic Coastal Wetlands - Nutrient enrichment - Nonnative species - Physical and hydrological alterations - Land development - Climate change and accelerated sea-level rise

Conservation and Restoration Efforts - Reduce wastewater; improve septic and sewage systems - Improve agricultural and lawn fertilization practices - Manage nonnative species - Restore tidal flow - Remove barriers to landward migration - Create and enforce zoning and development regulations - Lower and regulate CO2 and other greenhouse gas emissions

Impetus to Fund and Support

Alter

Wetland Structure and Function - Plant above- and belowground production - Species composition and abundance - Habitat diversity - Secondary production - Decomposition and soil respiration rates - Peat a