Wildlife and Wind Farms - Conflicts and Solutions: Onshore: Potential Effects (Volume 1) (Conservation Handbooks, Volume 1) 9781784271190, 1784271195

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Wildlife and Wind Farms, Conflicts and Solutions

Dedication This work is dedicated to my family: my wife Eleanor, with whom I share a vision of a better future for our planet; my children Merlin and Phoenix who are still young enough to wonder, and Morgan and Rowan, who took their place in society as women somewhere along the way; and my Mum and Dad. My Mum was taken from us before these books were completed and is acutely missed.

Wildlife and Wind Farms, Conflicts and Solutions Volume 1 Onshore: Potential Effects

Edited by Martin R. Perrow

Pelagic Publishing | www.pelagicpublishing.com

Published by Pelagic Publishing www.pelagicpublishing.com PO Box 725, Exeter EX1 9QU, UK Wildlife and Wind Farms, Conflicts and Solutions. Volume 1 Onshore: Potential Effects ISBN 978-1-78427-119-0 (Pbk) ISBN 978-1-78427-120-6 (ePub) ISBN 978-1-78427-121-3 (Mobi) ISBN 978-1-78427-122-0 (PDF) Copyright © 2017 This book should be cited as: Perrow, M.R. (ed) (2017) Wildlife and Wind Farms, Conflicts and Solutions. Volume 1 Onshore: Potential Effects. Pelagic Publishing, Exeter, UK. All rights reserved. No part of this document may be produced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise without prior permission from the publisher. While every effort has been made in the preparation of this book to ensure the accuracy of the information presented, the information contained in this book is sold without warranty, either express or implied. Neither the author, nor Pelagic Publishing, its agents and distributors will be held liable for any damage or loss caused or alleged to be caused directly or indirectly by this book. A catalogue record for this book is available from the British Library. The data in this book belong to the authors and contributors of the corresponding chapters and any further analyses or publications should not be undertaken without the approval of the authors. Colour reproduction of this book was made possible thanks to sponsorship by Vattenfall Wind Power Limited™. For more information visit https://corporate.vattenfall.com/ Cover images Top: Composite image of a White-tailed Eagle Haliaeetus albicilla pair at the Smøla wind farm in Norway. (Martin R. Perrow) Left: Drinking Leisler’s Bat Nyctalus leisleri, a frequent collision victim at wind farms when on migration. (Jens Rydell) Middle: Cranes preparing to lift the centre section of Turbine Tower No 8 at Scout Moor Wind Farm into position. (© Copyright Paul Anderson, licensed under an AttributionShareAlike 2.0 Generic [CC BY-SA 2.0] license) Right: Northern Lapwing Vanellus vanellus, a species that may avoid some wind farms. (Martin R. Perrow)

Contents Contributors

vi

Preface

ix

1

The nature of wind farms Gero Vella

1

2

Climate 24 Eugene S. Takle

3

Vegetation 40 Margarida R. Silva and Isabel Passos

4

Terrestrial invertebrates Sarah Elzay, Lusha Tronstad and Michael E. Dillon

63

5

Aquatic organisms William O’Connor

78

6

Reptiles and amphibians Jeffrey E. Lovich and Joshua R. Ennen

97

7

Birds: displacement Hermann Hötker

119

8

Birds: collision Manuela de Lucas and Martin R. Perrow

155

9

Bats 191 Robert M.R. Barclay, Erin F. Baerwald and Jens Rydell

10

Terrestrial mammals Jan Olof Helldin, Anna Skarin, Wiebke Neumann, Mattias Olsson, Jens Jung, Jonas Kindberg, Niklas Lindberg and Fredrik Widemo

222

11

A synthesis of effects and impacts Martin R. Perrow

241

Index

277

Contributors Shannon E. Albeke

Wyoming Geographical Information Science Center, University of Wyoming, Laramie, WY 82071, USA

Francisco Álvares

CIBIO/InBio, Centro de Investigação em Biodiversidade e Recursos Genéticos da Universidade do Porto, Campus Agrário de Vairão, 4485-661 Vairão, Portugal

Erin F. Baerwald

Biological Sciences, University of Calgary, Calgary, AB, Canada T2N 1N4 and American Wind and Wildlife Institute, 1110 Vermont Ave. NW, Washington DC 20005-3544, USA

Robert M.R. Barclay

Biological Sciences, University of Calgary, Calgary, AB, Canada T2N 1N4

Jeffrey L. Beck

Department of Ecosystem Science and Management, University of Wyoming, Laramie, WY 82071, USA

Espen Lie Dahl

Norwegian Institute for Nature Research (NINA), PO Box 8.5685 Sluppen, NO-7485 Trondheim, Norway

Manuela de Lucas

Applied Ecology Group, Ethology and Biodiversity Conservation, Estación Biológica de Doñana (CSIC), Spain

Michael E. Dillon

Department of Zoology and Physiology and Program in Ecology, University of Wyoming, Laramie, WY 82071, USA

Tobias Dürr

Landesamt für Umwelt, Gesundheit und Verbraucherschutz Brandenburg, Staatliche Vogelschutzwarte, Buckower Dorfstraße 34, D-14715 Nennhausen OT Buckow, Germany

Sarah Elzay

Department of Zoology and Physiology, University of Wyoming, Laramie, WY 82071, USA

Joshua R. Ennen

Tennessee Aquarium Conservation Institute, 201 Chestnut Street, Chattanooga, TN 37402, USA

Contributors  | vii Jan Olof Helldin

Calluna AB, Stockholm, Sweden

Hermann Hötker

Michael-Otto-Institut im NABU, Forschungs- und Bildungszentrum für  Feuchtgebiete und Vogelschutz, Goosstroot 1, D-24861 Bergenhusen, Germany

Snehalata V. Huzurbazar

Department of Statistics, University of Wyoming, Laramie, WY 82071, USA

Jens Jung

Department of Animal Environment and Health, Swedish University of Agricultural Sciences, Skara, Sweden

Jonas Kindberg

Department of Wildlife, Fish and Environmental Studies, Swedish University of Agricultural Sciences, Umeå, Sweden

Niklas Lindberg

Enetjärn Natur AB, Umeå, Sweden

Jeffrey E. Lovich

US Geological Survey, 2255 North Gemini Drive, MS9394, Flagstaff, AZ 86001, USA

Beatriz Martin

Migres Foundation, Huerta Grande, Ctra. N340 km 96.7, CP 11390, Spain

Mónia Nakamura

CIBIO/InBio, Centro de Investigação em Biodiversidade e Recursos Genéticos da Universidade do Porto, Campus Agrário de Vairão, 4485-661 Vairão, Portugal

Wiebke Neumann

Department of Wildlife, Fish and Environmental Studies, Swedish University of Agricultural Sciences, Umeå, Sweden

William O’Connor

ECOFACT Environmental Consultants Ltd, Tait Business Centre, Dominic Street, Limerick V94 NW81, Ireland

Mattias Olsson

EnviroPlanning AB, Gothenburg, Sweden

Alejandro Onrubia

Migres Foundation, Huerta Grande, Ctra. N340 km 96.7, CP 11390, Spain

Isabel Passos

Bioinsight – Ambiente e Biodiversidade, Lda, Portugal

Hans Christian Pedersen

Research Director, Norwegian Institute for Nature Research (NINA), PO Box 5685 Sluppen, NO-7485 Trondheim, Norway

Martin R. Perrow

ECON Ecological Consultancy Ltd, Unit 7 Octagon Business Park, Little Plumstead, Norwich NR13 5FH, UK

viii  |  Wildlife and Wind Farms, Onshore: Potential Effects Francisco Petrucci-Fonseca GRUPO LOBO, Departamento de Biologia Animal da Faculdade de Ciências da Universidade de Lisboa, Campo Grande 1749-016 Lisboa, Portugal Helena Rio-Maior

CIBIO/InBio, Centro de Investigação em Biodiversidade e Recursos Genéticos da Universidade do Porto, Campus Agrário de Vairão, 4485-661 Vairão, Portugal

Sara Roque

GRUPO LOBO, Departamento de Biologia Animal da Faculdade de Ciências da Universidade de Lisboa, Campo Grande 1749-016 Lisboa, Portugal

Jens Rydell

Department of Biology, Lund University, SE-22362 Lund, Sweden

Margarida R. Silva

Bio3 – Estudos e Projetos em Biologia e Valorização de Recursos Naturais, Lda, Portugal

Anna Skarin

Department of Animal Nutrition and Management, Swedish University of Agricultural Sciences, Uppsala, Sweden

K. Shawn Smallwood

3108 Finch Street, Davis, CA 95616, USA

Eugene S. Takle

Agronomy Department, Iowa State University, Ames, IA 50011, USA

Kaitlyn L. Taylor

Department of Ecosystem Science and Management, University of Wyoming, Laramie, WY 82071, USA

Carlos Torralvo

Migres Foundation, Huerta Grande, Ctra. N340 km 96.7, CP 11390, Spain

Lusha Tronstad

Wyoming Natural Diversity Database, University of Wyoming, Laramie, WY 82071, USA

Gero Vella

Renewable Energy Systems Limited, Egg Farm Lane, Kings Langley, Hertfordshire, WD4 8LR, UK

Fredrik Widemo

Department of Wildlife, Fish and Environmental Studies, Swedish University of Agricultural Sciences, Umeå, Sweden & Swedish Association for Hunting & Wildlife Management, Sweden

Preface Wind farms are seen to be an essential component of global renewable energy policy and the action to limit the effects of climate change. There is, however, considerable concern over the effects of wind farms on wildlife especially on birds and increasingly on bats. Environmental impact assessment, which has been adopted in many countries, should, in theory, reduce any impacts to an acceptable level. Although a wide range of monitoring and research studies have been undertaken, only a small body of that work appears to make it to the peer-reviewed literature. The latter is, however, burgeoning, concomitant with the interest in the interactions between wind energy and wildlife as expressed by the continuing CWW (Conference on Wind Energy and Wildlife Impacts) series of international conferences on the topic. In 2015, 391 participants from 33 countries attended CWW 2015 in Berlin. This will hopefully be exceeded at Estoril in Portugal in September 2017. It is hoped that relationships with researchers in key global producers of wind energy such as China and India, and the emerging markets in Brazil and Africa can become established. Lessons learned in mostly temperate Europe and North America need to be applied to subtropical and tropical climes. Here, in areas with higher biodiversity, it will be even more critical first to understand and then reduce and hopefully eliminate impacts upon wildlife. Even with specific knowledge of the literature and participation at CWW meetings, I came to the conclusion that it remained difficult for an interested party to judge possible effects on flora and flora and especially the prospects of ecosystem effects focusing on ecological interactions between affected habitats and their dependent species, or between species, one or more of which could be affected by wind farms. In other words, there was a clear need for a coherent overarching review of potential and actual effects of wind farms, and perhaps even more importantly, once that had been attained, how impacts could be successfully avoided or mitigated. Understanding the tools available to conduct meaningful research is also clearly fundamental to any research undertaken. A meeting with Nigel Massen of Pelagic Publishing in Cardiff in late 2012 at the Chartered Institute of Ecology & Environmental Management Renewable Energy and Biodiversity Impacts conference (where else?) crystallised the notion of a current treatise and the opportunity to bring it to reality. Even then, the project could not have been undertaken without the financial support of ECON Ecological Consultancy Ltd expressed as my time and the administrative help of Dr Sarah Eglington in selecting and inviting many of the authors. The industry is effectively divided into onshore and offshore disciplines that share many similarities such as potential displacement and collision of birds, but also differences such as the relative importance of noise, in the type and strength of effects upon wildlife. This provided a natural division into two compendia sharing common themes and threads within a similar framework. Each was to document current knowledge of the effects – the

x  |  Wildlife and Wind Farms, Onshore: Potential Effects conflicts with wildlife – and to provide a state-of-the-science guide to the monitoring and assessment tools and the means of avoiding, minimising and mitigating potential impacts – the solutions. The scope of coverage was to be global, although as a result of the concentration of different forms of the technology in different parts of the world, there was an inevitable bias in experience of the invited authors of the chapters within the different sections. Potential authors were carefully selected from the large number of academics and consultants now engaged in wind farm studies, for their influential contribution to the science. Fortunately, the rate of take-up was high. Many authors also proved keen to significantly extend their chapters, which resulted in the division of the two parts of the onshore compendium into two volumes; this one, Volume 1, describing the potential conflicts and Volume 2 outlining the solutions, as described above. In this Volume 1, the concept was to cover as wide a taxonomic spread as possible starting with Vegetation and including Terrestrial invertebrates, Aquatic invertebrates and fish, Reptiles and amphibians, (non-volant) Terrestrial mammals as well as Bats and Birds; the latter two groups being the sole focus of most previous reviews. The wealth of information on birds required two chapters according to the effects: Birds – displacement and Birds – collision. As such, chapters on poorly studied groups were to outline potential as well as realised effects and possible impacts. As well as chapters on the taxonomic groups, the scene was to be set by an introductory chapter on the Nature of wind farms, with a further chapter on Climate outlining the emerging science of climatic changes experienced as a result of the installation of onshore wind farms, which has ecological consequences. The effects of construction on the original habitats, including soils, are encompassed in the Vegetation chapter, with the Aquatic invertebrates and fish chapter outlining the hydrological consequences of the construction of some wind farms in particular localities. Otherwise, the construction of wind farms has similarities with other large-scale construction projects, the effects of which are dealt with in detail in other publications. A Synthesis of the effects and impacts upon all the taxonomic groups is also provided in a stand-alone chapter at the end of the volume. This also aimed to fill any gaps in the preceding chapters and as it was completed after all other chapters also had the benefit of incorporating more recent information published in the intervening period. To promote coherence within and across volumes, a consistent style was adopted for all chapters, with seven sub-headings: Summary, Introduction, Scope, Themes, Concluding remarks, Acknowledgements and References. For ease of reference, the latter are reproduced after each chapter. The carefully selected sub-headings break from standard academic structure (i.e. some derivative of Abstract, Introduction, Methods, Results, Conclusions) in order to provide flexibility for the range of chapters over the two volumes, many of which are reviews of information, whilst others provide more prescriptive recommendations or even original research. Some sub-headings require a little explanation. For example, the Summary provides a ~300-word overview of the entire chapter, whilst the Concluding remarks provide both conclusions and any recommendations in a section of generally ~500 words. The Scope sets the objectives of the chapter, and for the benefit of the reader describes what is, and what is not, included. Any methods are also incorporated therein. The Themes provide the main body of the text, generally divided into as few subheading levels as possible. Division between effects during construction and operation was generally avoided as this increased the number of sub-headings and led to unwieldy structure. Any clear differences in effects between different stages of wind farm construction and operation are incorporated into specific sub-headings.

Preface  | xi As well as being liberally decorated with tables, figures and especially photographs, which are reproduced in colour courtesy of sponsorship by Vattenfall, most chapters also contain Boxes of information. These were designed to be provide particularly important examples of a particular point or case or suffice as an all-round exemplar and ‘stand-alone’ from the text. In some cases, these have been written by an invited author(s) with the principal that it is better to see the words from the hands of those involved than to paraphrase published studies. Boxes also provided an opportunity to widen the geographic spread of information in the chapter. I take any deficiencies in the scope and content in this and its sister volume to be my responsibility, particularly as both closely align to my original vision, and many authors have patiently tolerated and incorporated my sometimes extensive editorial changes to initial outlines and draft manuscripts. My sincere thanks to all 23 chapter authors and 16 additional Box (case study) authors for their contributions. From my perspective, at least, there can be no satisfaction without at least a little pain. I hope the authors feel the same. I also hope that these volumes are a further step towards the sustainable development of wind farms and the ultimate goal of win–win1 scenario for renewable energy and wildlife Martin R. Perrow ECON Ecological Consultancy Ltd 7 November 2016

1 Kiesecker, J.M., Evans, J.S., Fargione, J., Doherty, K., Foresman, K.R., Kunz, T.H., Naugle, D., Nibbelink, N.P. & Niemuth, N.D. (2011) Win–win for wind and wildlife: a vision to facilitate sustainable development. PLoS ONE 6: e17566.

CHAPTER 1

The nature of wind farms GERO VELLA

Summary This chapter discusses the technological aspects of wind power; the policy, planning and statutory requirements underpinning its deployment; and the development process from site selection through to permit award, mitigation and monitoring. While this chapter presents a global perspective, many of the examples provided have a European focus drawn from the author’s own experiences in developing wind farms in the UK. Research for the chapter was undertaken through a literature review of academic papers, government and industry reports and grey literature. The review found that policy support worldwide has led to the construction of wind farms in more than 90 countries and a contribution of around 3% to the renewable energy mix globally, but with much higher contributions in areas where there is a good wind resource. Large three-bladed horizontal-axis wind turbines continue to dominate commercial wind farms, but deployment of small to medium-sized turbines for domestic and rural applications is increasing, in addition to the use of vertical-axis wind turbines in urban locations. The focus of Environmental Impact Assessment as a key stage in the development process is discussed and the importance of robust site selection is highlighted as mitigation against potential environmental impacts.

Introduction Since early history, humans have harnessed the power of the wind to propel boats, grind grain and pump water. When the generation of electricity became sufficient for industrial purposes at the end of the nineteenth century, the first prototypes of modern wind turbines were built using technology based on the classical windmill. Generally, these were to provide power to farms and remote locations. It was not until the oil crisis of the 1970s, with the consequential increase in the price of oil, that interest was raised in identifying ecologically and commercially viable alternative energies and wind power came into focus. For example, in the USA, the Federal Government worked with the National Aeronautics and Space Administration (NASA) to research and develop utility-scale wind

2  |  Wildlife and Wind Farms, Onshore: Potential Effects turbines (Wind Energy Foundation 2015). Thereafter, concerns were raised over the environmental and economic threat of global warming due to a number of ‘greenhouse’ gases (GHGs). Thus, increasing atmospheric concentrations of GHGs, such as carbon dioxide and methane resulting from industrial processes, the refining and burning of fossil fuels, and intensive livestock farming, provided additional stimulus for research and development into the potential of wind power (Box 1.1).

Box 1.1  Renewable energy policy as the basis for wind farm development A global perspective Global warming has become the most prominent environmental issue of our time. Growing public awareness of the effects of elevated global temperatures has been driven by clear signs around the world that climate change is already happening. From the UK Stern Review in 2007 (Stern 2007) to the latest Intergovernmental Panel on Climate Change (IPCC) reports (IPCC 2014), stark warnings are coming from both scientific and economic experts who think that climate change is a reality and that the consequences to the environment and our society will be significant. However, it was the climate change research undertaken in the 1970s and 1980s that led to the development of the United Nations Framework Convention on Climate Change (UNFCCC) at the Rio Convention on Climate Change and Biodiversity in 1992. Following the Rio Convention, targets were set for ratifying countries to reduce their greenhouse gas (GHG) emissions, as defined by the Kyoto Protocol, which was adopted in 1997 and came into legal force in 2005. This protocol requires that a number of industrialised countries reduce their GHG emissions by an average of 5% below 1990 levels during the first commitment period of 2008 to 2012, with additional reduction in the second period from 2013 to 2020 (UNFCCC 2015a). The protocol has been described as a historic ‘first step’ to controlling GHG and provided a basic framework around action to combat climate change. Importantly, it has led many industrialised countries to put in place the policies and action plans needed to achieve emissions cuts. For example, the European Union (EU) has made commitments to a reduction of 20% by 2020, discussed further below, and China, the world’s biggest emitter of carbon dioxide (Oliver et al. 2012), created a National Action Plan on Climate Change in 2007. The ‘Paris Agreement’ of the UNFCCC in December 2015 is set to have the same impact as the Kyoto Protocol, with almost 200 world leaders pledging commitments to reducing GHG emissions and holding the increase in global average temperatures to below 2ºC over pre-industrial levels (UNFCCC 2015b). These targets will be reviewed on a five-yearly basis from 2020 with an aim of achieving ‘GHG emissions neutrality’ (net zero anthropogenic GHG emissions) in the second half of the century. A move towards the use of renewable energy is therefore essential to achieving this aim. Encouragingly, the Renewable Energy Policy Network for the 21st Century (REN21) reports that more than 160 countries have established renewable energy targets and support policies in place, including feed-in tariffs, tax credits, ‘green’ certificates, mandatory targets, capital cost subsidies, and support for research, development and demonstration (REN21 2015).

The nature of wind farms  | 3 Wind power is an important component of the renewable energy mix. Although it only contributes about 3% to global renewables when considered alongside hydroelectric and biomass [Global Wind Energy Council (GWEC) 2015b], it is a significant contributor in markets where there is a good resource. Wind power accounted for more than 50% of renewable energy generation during 2014 in the UK and provided 10% of national electricity requirements (RenewableUK 2015b). In the same year, wind power accounted for nearly 40% of Denmark’s national demand (GWEC 2015b), while cumulatively across Europe it meets just over 10% of EU electricity requirements (European Wind Energy Association 2015).

The European perspective The EU Renewable Energy Directive (EU 2009a) is the key policy driving renewables and a move to a low-carbon economy in Europe. The directive sets a binding target of 20% final energy consumption from renewable sources by 2020. To achieve this, EU countries have committed to reaching national renewables targets set by the Directive, which are based on a number of factors, including the existing renewable energy generation in a country and its gross domestic product. These targets range from 10% in Malta to 49% in Sweden (EU 2009a). The Directive requires that EU countries prepare and adopt National Renewable Energy Action Plans outlining the actions they intend to take to meet their targets. As a result of the Directive and the National Action Plans, REN21 reports that renewable energy projects represented 72% of new electricity generating capacity in 2013, which was the majority for the sixth consecutive year. This is in stark contrast to the situation a decade earlier, when conventional fossil fuel generation accounted for the majority of new capacity (REN21 2015).

The UK perspective The Climate Change Act 2008 [and Climate Change (Scotland) Act 2009] set the UK commitments to reducing GHG emissions and includes key policies driving wind power. The Act puts a duty on the Secretary of State for Energy and Climate Change to ensure that the net UK carbon account for the year 2050 is at least 80% lower than the 1990 baseline. The Act aims to enable the UK to become a low-carbon economy and gives ministers powers to introduce the measures necessary to achieve a range of GHG reduction targets. An independent Committee on Climate Change has been created under the Act to provide advice to the UK Government on these targets and related policies.

The past decade has seen unprecedented deployment of wind power worldwide driven by renewable energy targets established in more than 160 countries [Renewable Energy Policy Network for the 21st Century (REN21) 2015]. The World Wind Energy Association (WWEA 2015) reports a global installed capacity of nearly 370,000 megawatts (MW) of wind power, the majority of which is distributed across Asia, North America and Europe (Figure 1.1). At the time of writing, China is the world leader, generating over 30% of global wind power, followed by the USA, Germany, Spain and India, with emerging markets in Brazil and Africa. Furthermore, the majority of the generation is from onshore wind, with only 2.5% being generated offshore by the end of 2014 [Global Wind Energy Council

4  |  Wildlife and Wind Farms, Onshore: Potential Effects

Figure 1.1  (a) Global distribution of installed wind power capacity (MW) by region; (b) installed wind power capacity (MW) for the top ten countries. (GWEC 2015a)

(GWEC) 2015a], although the huge potential for offshore wind should be noted (see Wildlife and Wind Farms: Conflicts and Solutions, Volume 2: Offshore). In addition to renewables targets and incentives such as green tariffs, the GWEC and Greenpeace International (2014), together with Zindler (2015), report that in an increasing number of world markets, wind power is the lowest cost option when adding new generation capacity to the electricity grid. As a result, wind power has now firmly established itself as a mainstream option for new electrical generation. Yet despite the rapid deployment of onshore wind, there are still a number of permitting barriers. These relate to potential impacts on birds, bats and other wildlife, and social concerns such as the visual and cultural setting of wind farms and their performance and value. This has led to an application refusal rate of approximately 50% per year in the UK between 2013 and 2014 (RenewableUK 2014b; 2015b). While many of the refusals relate to concerns over impacts to local communities, wind farms do present a number of potential impacts to different

The nature of wind farms  | 5 wildlife taxa which may contribute to delays in permitting or refusal. In brief, key impacts during construction and decommissioning include direct and indirect impacts associated with displacement of wildlife or their prey from construction noise and activity, habitat modification from installation of the wind turbines, access roads and other infrastructure, and habitat loss resulting from, for example, the removal of hedgerows and trees. During operation, key concerns relate to the collision risk to birds and bats, or their displacement if they avoid the wind farm and its surrounding area owing to turbine operation and maintenance or visitor disturbance. Displacement can include barrier effects in which birds are deterred from using their normal routes to feeding or roosting grounds. For reviews, see Hötker et al. (2006), Arnett et al. (2007), May and Bevanger (2011), Rydell et al. (2012), Arnett and Baerwald (2013) and Gove et al. (2013). It is predicted that wind power could reach nearly 2 million MW by 2030, equating to approximately 19% of global electricity requirements and a saving of over 3 billion tonnes of carbon dioxide emissions annually (GWEC 2014). To achieve this, there needs to be continued research and development into wind power technology, supported by global and national policies. In addition, both governments and wind farm developers need to work together to reduce continued concerns over the potential environmental and social barriers.

Scope Three themes are discussed in this chapter: •

Technological aspects of wind power

•

Policy, planning and statutory requirements

•

The development process.

The first theme will review the technology: the types of wind turbines in use and how they work. The theme focuses on three-bladed wind turbines, which are most commonly deployed in wind farms, but also considers small to medium-sized wind turbines and vertical-axis wind turbines. The second theme will consider the planning and statutory permitting requirements, focusing on those relative to considering wildlife and the environment, using the UK as a specific example. The third theme will describe the development process that wind farm companies typically undertake in identifying wind farm sites, from initial site selection through to mitigation and monitoring. Although this chapter presents a global perspective, many of the examples provided have a European focus drawn from the author’s own experiences in developing wind farms in the UK.

Themes The technology of wind power Generation of electricity Wind turbines use the kinetic energy of the wind to generate electrical energy. Traditional turbines consist of three main elements: the tower, the nacelle and, most commonly, three

6  |  Wildlife and Wind Farms, Onshore: Potential Effects rotor blades. The steel tower is fixed to the ground by a concrete foundation. The nacelle, composed of glass-fibre reinforced plastic, sits at the top of the tower and is connected to the blades via the rotor hub. Both hub and blades are also typically composed of glassfibre reinforced plastic. A rotor shaft inside the nacelle connects the hub to the generator, usually via a gearbox. The wind blows on the angled blades of the rotor, causing the rotor shaft to rotate and convert some of the wind’s kinetic energy into mechanical energy. The generator converts this mechanical energy into electrical energy. Traditional wind turbines employ a gearbox to increase the rotational speed of the rotor shaft and, therefore, the efficiency of the generator (Figure 1.2). An anemometer on top of the nacelle monitors wind speed and direction, starting the turbine when wind speeds are sufficient, the ‘cut-in speed’, and shutting it down when wind speeds exceed its maximum operating speed. In general, turbines cut in at around 4 or 5 metres per second (m/s) and shut down at speeds exceeding 30 m/s (Boyle 2004). Additional sensors can also direct (yaw) the nacelle and rotor into the wind, and pitch (feather) the blades to control energy capture.

Figure 1.2  How a wind turbine generates electricity.

A transformer at the base of the turbine converts the electricity generated by the wind turbine at around 700 volts (V) to a more typical voltage for distribution to electrical distribution networks such as 33,000 V, which is equal to 33 kilovolts (kV). Where a turbine connects to a high-voltage distribution network, usually when the turbine is part of a wind farm, buried cables transfer the medium voltage electricity to a substation where it is converted to high voltage (132/275/400 kV). The high-voltage electrical distribution network transmits the electricity around the country. The process of electricity generation and distribution is illustrated in Figure 1.3.

The nature of wind farms  | 7

Figure 1.3  Electricity generation and distribution.

Turbine design There are two main classes of wind turbine: those whose rotors spin about a horizontal axis, termed horizontal-axis wind turbines (HAWTs), and vertical-axis wind turbines (VAWTs), whose rotors spin about a vertical axis (Figure 1.4). HAWTs typically have either two or three blades. Three-bladed HAWTs are operated ‘upwind’, with the blades facing into the wind. Sensors mounted above the turbine nacelle orientate the rotor with respect to the wind. The rotor speed as well as the power output can be controlled by pitching the rotor blades along their longitudinal axis. This blade pitching allows the aerodynamically engineered blades to control lift and thus power generation from the wind, but also acts as a form of protection against extreme wind conditions and overspeed through pitching to reduce lift. Most early HAWT designs operated at fixed speeds and utilised brakes to hold the blades until a sufficient wind speed was detected. Modern HAWTs (Figure 1.5) operate at variable speeds with sensors allowing the rotor blades to match the wind speed until peak or ‘rated’ speeds are attained. This allows cost-effective energy generation at low speeds in light winds.

Figure 1.4  Classes of modern wind turbine. (Renewable Energy Systems Ltd)

8  |  Wildlife and Wind Farms, Onshore: Potential Effects

Figure 1.5  An example of a h ­ orizontal-axis wind turbine at Hornberget wind farm, Sweden. (Nordisk Vindkraft)

Although one- and two-bladed wind turbines are available, the European Wind Energy Association (EWEA) notes that three-bladed designs are most commonly deployed in commercial wind farms as they are structurally efficient (or balanced), in addition to providing other benefits including lower acoustic noise emissions and visual impacts associated with the less frequent passage of only a single blade or two blades in comparison to three blades (EWEA 2004). To further improve the energy capture of commercial three-bladed HAWTs, blade aerodynamics has been a key focus of research and development. VAWTs can be divided into two major groups: Savonius type, which use aerodynamic drag to extract power from the wind; and Darrieus type, which use lift (Figure 1.6). The advantages of VAWTs are that they can utilise winds from all directions, unlike traditional HAWTs which need to track the oncoming wind. This is an important advantage in locations where winds are turbulent, gusty and constantly changing direction, such as in towns and cities. The omnidirectional nature of electricity generation in VAWTs also provides mitigation against ‘down-time’ lost to the requirement to yaw or swivel to face the wind (Boyle 2004). In addition, the location of the gearbox and generator at the base of the turbine allows easy access and therefore generally reduces maintenance costs.

Turbine size

Figure 1.6  An example of a Darrieus-type ­vertical-axis wind turbine. (Gero Vella)

Modern wind turbines have shown a significant increase in size and rotor diameter since the 1970s and 1980s, leading to greater power generation. EWEA (2004) reports that in spite of repeated predictions that turbine size would level off at an optimum mid-range, the size of turbines deployed in commercial wind farms has increased year on year. From rotor blade diameters of 15–20 m in the 1980s, the commercial market is now ready to deploy turbines with rotor blade diameters greater than 125 m atop

The nature of wind farms  | 9 Table 1.1  Definitions of micro, small and medium-sized wind turbines according to RenewableUK (2010).

Power (kW)

Annual energy production (kWh)

Total height (m)

Micro wind

0–1.5

Up to 1,000

10–18

Small wind

1.5–50

Up to 200,000

15–35

Medium wind

50–500

Up to 1,800,000

25–55

hub heights exceeding 100 m, such as the Enercon E-126 rated at 7,580 kW (Enercon 2015). Permitting applications for onshore wind farms in the UK regularly assume a turbine tip height of around 150 m for the purpose of impact assessment. Offshore, wind turbine sizes are even larger, as shown by planning permission for Creyke Beck offshore wind farm (Forewind 2013), which incorporates 10,000 kW (or larger) wind turbines with a maximum blade tip height of 313 m above sea level. For further information on the nature of offshore wind turbines, see Jameson et al, Chapter 1, Volume 3 of this series. In parallel with the trend of increasing rotor blade length and the size of turbines, there has also been significant increase in the development and deployment of small and medium-sized wind turbines. These classes of turbine range in size from micro-turbines less than 20 m in height to medium-sized wind turbines of up to 55 m (Table 1.1). Renew­ ableUK (2014a) commonly categorises small wind turbines as single-turbine installations, usually owned by individual homeowners or farmers for on-site electricity consumption, such as the example shown in Figure 1.7. In comparison, medium-sized wind projects are larger developments that may also supply electricity to the grid, and are often investor financed. Importantly, RenewableUK notes that despite the size differences, small and medium-sized projects are typically installed to provide on-site electricity to homes, farms and small communities. They only use the electricity grid to sell back any excess generation above their immediate energy needs. This is in contrast to large-scale wind farms that feed all their generated electricity direct to national electricity grids. The WWEA reports that globally, 806,000 small wind turbines were in operation by 2012 (WWEA 2014), with over 25,000 small and medium-sized wind systems reported in the UK alone (Renew­ ableUK 2015a). With inevitable advances in the manufacturing processes, the cost of these turbines is likely to decrease and one would imagine that their deployment would increase accordingly. Crucially, the small to medium-sized wind market Figure 1.7  A domestic wind turbine providing provides the diversity of scale to allow a power to a residential property. (Nick Bristow)

10  |  Wildlife and Wind Farms, Onshore: Potential Effects wider range of society to implement renewable energy options to suit their needs, thus reducing our reliance on energy from fossil fuels.

Wind farms The term ‘wind farm’ generally refers to more than two wind turbines connected to the national electricity grid. Modern wind farms tend to comprise turbines that generate more than 1 MW, and typically 2 MW of power. As wind farms are only as productive as the wind resource that powers them, they tend to be sited at elevated and exposed locations where there are good average wind speeds and a minimum of obstacles and obstructions such as trees, hills and other buildings to affect the wind resource. Other important aspects of their siting include sufficient separation from noise-sensitive neighbours, good access to the electricity grid, good site access to transport the turbine components to the site, and an absence of special environmental or landscape designations (see The development process, below). With policy support for renewable energy and wind power globally, the size of wind farms keeps increasing. At the time of writing, Alta Wind Energy Center (AWEC) in California, USA, is the largest single wind farm in the world. Once complete, it will have a capacity of 1,548 MW generated from up to 600 turbines (California Energy Commission 2015). Several of the world’s largest wind farms are in the USA, with others scattered across the globe in Asia, Australasia and Europe (Table 1.2). In contrast, the UK’s largest site at Whitelee near Glasgow, at 215 turbines producing 539 MW, is around a third of the size and capacity of the current world leader. It is, however, the second largest wind farm in Europe. Table 1.2  A selection of some of the largest wind farms in the world.

Wind farm

Capacity (MW)

Number of turbines

1,548

600

Roscoe Wind Farm, Texas, USA

781

634

Horse Hollow Wind Energy Center, Texas, USA

735

421

Capricorn Ridge Wind Farm, Texas, USA

662

407

Dabancheng Wind Farm, Xinjiang Uygur, China

500

300+

Fântânele-Cogealac Wind Farm, Romania

600

240

Whitelee Wind Farm, Scotland

539

215

Macarthur Wind Farm, Australia

420

140

Alta Wind Energy Center, California, USA

Planning and statutory requirements In the UK, a number of government policies and parliamentary acts govern the planning process for onshore wind. Key policies include the UK Government’s National Planning Policy Framework, the National Policy Statement for Renewable Energy Infrastructure, the Planning Act and the Localism Act, all of which apply to England and Wales; the Scottish Planning Policy for Renewable Energy, which applies to Scotland; and the Planning Policy Statement for Northern Ireland. Further requirements are set out in the individual Town and Country Planning Acts for England, Wales and Scotland.

The nature of wind farms  | 11 Table 1.3  Wind farm consenting regimes in the UK.

Project capacity

Country

Consenting regime

Over 50 MW

England and Walesa

Planning applications for projects above 50 MW are treated as Nationally Significant Infrastructure Projects (NSIPs), and consented under the Planning Act 2008. Consent is awarded as a Development Consent Order (DCO). For such projects, the application is examined by the Planning Inspectorate and a recommendation is made to the Secretary of State for Energy and Climate Change, who will make decisions in accordance with the National Policy Statements and any other relevant policies

Scotland

Planning applications for projects above 50 MW are consented by the Scottish Executive under Section 36 of the Electricity Act 1989

Northern Ireland

All planning applications for wind farm proposals in Northern Ireland are consented under the Town and Country Planning Act. Examination and consent are awarded by the Department of the Environment Planning Service, irrespective of proposed capacity

UK-wide

Planning applications for projects under 50 MW are examined and consented by Local Planning Authorities under the Town and Country Planning Act across England, Wales, Scotland and Northern Ireland

Under 50 MW

Permit applications for wind farm projects over 50 MW in England and Wales will be consented by the Local Planning Authority under the Town and Country Planning Act from 2016. a 

The size of a proposed wind farm has a direct bearing on its planning process, with different consenting regimes for proposed wind farms of greater or less than 50 MW (Table 1.3). An important first step in the examination process for all applications is to determine whether they are in line with national, regional and local planning policies. It is therefore the duty of the applicant, invariably the wind farm developer, to ensure that the application meets all relevant policy requirements. Since the introduction of Environmental Impact Assessment (EIA) in the USA through the 1969 National Environmental Policy Act, many industrialised counties have adopted some requirement for the consideration of potential impacts on the environment during the development phase of infrastructure projects (Table 1.4). Within the European Union (EU), this requirement is implemented through the EIA Directive (EU 2014), which requires an assessment to be carried out by the competent national authority in each member state for certain projects, such as wind farms (Box 1.1). Several other EU directives also influence the development process, such as the Habitats Directive (EU 1992) and Birds Directive (EU 2009b). These EU directives are discussed in more detail in Box 1.2. From a developer’s perspective, the EIA process provides an opportunity to mitigate potential significant effects through the project design process. Depending on the results of the assessment, developers may be obligated to implement mitigation strategies and monitoring programmes where significant impacts are identified that cannot be mitigated through the design process and/or to validate the results of the assessment in the absence of an existing evidence base for the potential impact. The practice of actually undertaking EIA is considered further in the next subsection, The development process.

12  |  Wildlife and Wind Farms, Onshore: Potential Effects Table 1.4  Legislation implementing Environmental Impact Assessment (EIA) in selected industrialised countries around the world.

Country

Key legislation implementing EIA

Australia

The Environment Protection and Biodiversity Conservation Act 1999

Canada

The Canadian Environmental Assessment Act 2012

Australia

The Environment Protection and Biodiversity Conservation Act 1999

England

Town and Country Planning (Environmental Impact Assessment) Regulations 2011

EU

European Union Directive (85/337/EEC) on Environmental Impact Assessments

Japan

Environmental Impact Assessment Law 1997

India

Environment Protection Act 1986

Rebublic of Korea

Environmental Preservation Act 1979

USA

National Environmental Policy Act 1969

Box 1.2  European Union directives relevant to wind farm assessment Membership of the European Union (EU) requires implementation of its directives into national legislation. Several of these directives, as described below, apply to the permitting of wind farms.

Environmental Impact Assessment (EIA) Directive The EIA Directive (EU 2014) requires an assessment to be carried out by the competent national authority in each member state for certain projects, which may have a physical effect on the environment. The purpose of the EIA is to aid the decision-making process by providing the competent authority with a full account of the likely significant environmental effects. The directive specifies the need to consider direct and indirect impacts of a positive or negative nature on the following receptors: human beings, fauna and flora, soil, water, air, climate and the landscape, material assets and cultural heritage, and the interaction between these receptors. Furthermore, it requires consideration of potential cumulative and trans-boundary impacts between member states. This is a key directive for European developers as wind farms require mandatory EIA.

Strategic Environmental Assessment (SEA) Directive The SEA Directive (EU 2001c) seeks to provide a high level of protection of the environment by integrating environmental considerations into the process of preparing certain plans and programmes. The aim of the Directive is to contribute to the integration of environmental considerations into the preparation and adoption of plans and programmes by requiring that an environmental assessment is carried out of certain plans and programmes which are likely to have significant effects on the environment. The key difference between EIA and SEA is geographic scale: whereas

The nature of wind farms  | 13 EIA is undertaken at the project level, SEA requires consideration of the potential environmental impacts associated with a plan or programme of projects. As a result, the SEA must be prepared or adopted by an authority (at national, regional or local level) rather than a developer.

Habitats and Birds Directives European nature conservation policy is based on two main pieces of legislation: the Birds Directive (EU 2009b) and the Habitats Directive (EU 1992). The later focuses on the protection of wild species and their habitats. Each member state is required to identify sites of European importance termed Special Areas of Conservation (SACs), and to put in place management plans where necessary. Under the former, member states are required to classify Special Protection Areas (SPAs), which are similar to SACs and may overlap at times. The Habitats and Birds Directives are particularly pertinent to European wind farm developers as they are required to carry out a Habitats Regulation Assessment (HRA) (EU 2001a) where a plan or project (in this case a wind farm proposal) is likely to have a significant effect upon a European site, either individually or in combination with other projects. This is in addition to the EIA. The HRA is undertaken in stages, with progression to each stage based on the findings of the previous stage. A description of each stage, based on EU (2001a), is given below: •

Stage 1 – Screening: The process of identifying the likely impacts of a project

•

Stage 2 – Appropriate assessment: The consideration of the impacts on the

•

Stage 3 – Assessment of alternatives: Examination of alternative ways of

•

Stage 4 – Imperative reasons of overriding public interest (IROPI): Consid-

upon a European site, either alone or in combination with other plans and projects, and considering whether the impacts are likely to be significant. If likely significant effects cannot be discounted, Stage 2 must be undertaken. integrity of the European site, either alone or in combination with other plans and projects, with regard to the site’s structure and function and its conservation objectives. Where likely significant effects are identified, an assessment of mitigation options must be carried out to determine adverse effects on the integrity of the site. If these mitigation options cannot avoid adverse effects then development consent can only be given if Stages 3 and 4 are followed. achieving the objectives of the project to establish whether there are solutions that would avoid or have a lesser effect on European sites. eration of whether a development is necessary; IROPI is undertaken where no alternative solution exists and where adverse impacts remain. If it is decided that the development should be permitted for IROPI, potential compensatory measures needed to maintain the overall coherence of the site or integrity of the European site network will need to be identified. Generally, there is a requirement to ensure that the compensation works satisfactorily before construction of the development can begin.

14  |  Wildlife and Wind Farms, Onshore: Potential Effects

The development process The development process undertaken by wind farm developers encompasses initial selection studies for a potential wind farm site through to its construction, while incorporating the implementation of mitigation measures and/or monitoring programmes. The process has five key stages: site selection, pre-application, application determination, preconstruction and construction/operation (Figure 1.8).

Figure 1.8  Key stages in the development process.

Site selection Site selection is an important stage in the development process as location plays a vital role in the performance and efficiency of a wind farm, but also allows developers to identify sites where potential effects on local communities, wildlife and landscape will be minimised. Geographic information systems (GIS) are a key tool in this process. These systems are designed to capture, store, manipulate, analyse, manage and present all types of spatial or geographical data. Generally, they comprise a base map of the area of interest into which data for relevant attributes can be incorporated. The first stage in site selection is the identification of areas that provide a suitable wind resource. Exposed sites, coastal locations and sites at higher altitudes often provide this requirement and there are a number of resources that can assist in this processes. In the USA, the Department for Energy hosts wind resource maps that show the predicted mean wind speed across the country at 80 m with links to state-level wind maps of finer resolution (US Department of Energy 2015). The European Environment Agency (EEA) provides a similar service for Europe (EEA 2009), and wind resource maps catering for ‘small’, ‘medium’ and utility-scale wind turbines are provided by the Met Office in the UK (Met Office 2015). The second stage applies the location of potential sites with a good wind resource against known sensitivities of the receiving environment. However, data on the required resolution to make decisions about the suitability of a site are often lacking and generally

The nature of wind farms  | 15 not available until the developer has undertaken expensive site-specific surveys. To mitigate this, many countries have started to produce strategic location guidance to assist developers with this process by highlighting areas of higher and lower sensitivity to provide developers with some insight into locations where development may be more acceptable. Good examples of such guidance are provided by Scottish Natural Heritage (SNH) for Scotland (SNH 2002) and the California guidelines for reducing impacts to birds and bats from wind energy development (California Energy Commission 2007). Sensitive areas may include those protected for their natural beauty, such as national parks, cultural importance or the habitats and species that they support. In the UK, this includes protected areas such as national nature reserves and European designations such as Special Protection Areas for birds (Box 1.2). Development in or close to protected areas is not always precluded. However, demonstration that a proposed wind farm will not adversely impact the features and/or management objectives of a protected area will be required. As a result, developers often avoid such areas as demonstrating ‘no impact’ is likely to be much more onerous and require collection of more extensive site-specific data (temporarily or spatially) and assessment with corresponding higher development costs and timescales and an overall greater development risk. The third stage considers the results of stage one and two against a number of required attributes, such as suitable road access and proximity of potential connections to the national electricity grid, in addition to known constraints. These include proximity to towns and villages, railway lines, airports and military installations, in addition to wildlife reserves and other protected areas discussed above. Once the attributes and constraints have been complied, a risk-based approach is used to examine attributes (both positive and negative) and uncertainties to identify sites with the greatest potential. A site visit is often required to allow developers to use experience and human judgement to make a final assessment. At some locations it may be necessary to erect meteorological towers to provide extra information on wind resource and feed into the decision-making process, in addition to preliminary consultation with key stakeholders to gain local knowledge and opinion. Wind flow modelling may also be undertaken during site selection or early in the pre-application stage. Wind speeds can vary considerably across a wind farm site if the terrain is undulating rather than flat. Wind flow modelling software is used to calculate these variations in wind speed, allowing the placement of wind turbines in the site to optimise the wind resource.

Pre-application The pre-application stage covers the period between identification of a potential or preferred wind farm site(s) through to application for a permit or consent to construct the project. In most countries around the world, EIA is a key focus and requirement of this stage, as discussed in Planning and statutory requirements (see above), owing to the potential impacts associated with poorly sited wind farms discussed in the Introduction section of this chapter. The EIA process is typically seen as a series of steps with a number of key components, namely screening, scoping and assessment of the potential impacts, against which public consultation is undertaken before a decision to consent (or modify or reject) is made (Figure 1.9). Screening is the process of determining whether a proposed project requires an EIA based on the expected impact(s) of the project and its relative significance. This process is

16  |  Wildlife and Wind Farms, Onshore: Potential Effects

Figure 1.9  Basic Environmental Impact Assessment (EIA) process and components.

generally undertaken by the regulator (the decision-making authority), such as local or national government, and results in one of four main outcomes (Salvador et al. 2000): •

No requirement for EIA

•

Requirement for a limited EIA

•

Requirement for a full and comprehensive EIA

•

Requirement for further studies to determine the level of EIA required.

Most countries around the world, including the UK, list the type of projects that require mandatory EIA in legislation (Christensen & Kørnøv 2011), negating the strict need for screening. Wind farm proposals are generally included in these lists and, as a result, some projects may skip this stage and proceed directly to scoping. However, screening is still advised as it can offer early opportunities for consultation on the suitability of a proposed site. The United States Fish and Wildlife Service (USFWS) advocates this approach in its guidance for land-based wind energy projects (USFWS 2012), and the EIA Directive in Europe (Box 1.2) also advises a staged approach that includes the ‘screening’ of potential wind farm projects to determine high-level issues and the need for EIA. Scoping is then undertaken to determine the content and extent of matters that should be covered in the environmental information to be submitted to the regulator (EU 2001b). In the UK, the Chartered Institute of Ecology and Environmental Management (CIEEM 2006) notes the key benefits of scoping to include: •

Early stakeholder identification, engagement, input and identification of issues of concern

•

An assessment focused on key, likely significant impacts on known receptors, their inter-relationships and sensitivities

•

Clear terms of reference for all engaged in the EIA, including an understanding of the criteria that will be used to evaluate the significance of their findings

•

Early identification of existing data and data gaps

•

Justification for the exclusion of issues ‘scoped out’ from the EIA

•

Early identification of the need for seasonally dependent surveys so that they can be accommodated in the schedule of work.

Additional information such as proposed survey and impact assessment methodologies add value to the scoping process by reducing the potential for challenges to the survey and assessment approach at the decision stage. This is particularly important for receptors that lack a single standard survey approach, such as birds, where there are a number of potential survey methodologies depending on the species that may be present, or for which project-receptor specific assessment criteria may need to be agreed. Scoping documents are often made available for public consultation, particularly to the local community and stakeholders that may be directly affected by the proposal. Such exercises can provide a very effective means of capturing local knowledge of the environment in and around a proposed project, while also providing an opportunity for the public

The nature of wind farms  | 17 to feed into the project design process. It also allows developers an early opportunity to mitigate any concerns raised. For this reason, public consultation generally continues throughout the pre-application stage. Scoping documents usually contain the following information: •

A description of the proposed project, its location and environmental setting information

•

Project options and alternatives

•

Information on the existing human, physical and biological environments

•

Potential negative and positive impacts on these environments from the construction, operation and decommissioning of the proposed project

•

Potential mitigation options and monitoring programmes.

Following scoping and agreement on the focus of the EIA, the next stage is data acquisition to describe the existing environment. Although this may be achieved through a review of existing data, there is usually a need to acquire new data through survey and census. The European EIA Directive (Box 1.2) specifies the need to consider the following receptors: human beings, fauna and flora, soil, water, air, climate and the landscape, material assets, cultural heritage and the interaction between these receptors. Depending on the scale of the proposed project, and with respect to species sensitive to wind farm construction and operation or protected species in particular, there is generally a need to undertake surveys during key seasons or periodically over a 12-month period. In some cases, it may be necessary to undertake surveys over several seasons or years to establish inter-annual variation. As mentioned earlier, it is good policy to ensure that the methodologies used to collect and analyse data are agreed with the regulator and appropriate stakeholders to mitigate their challenge at the application stage. The results of survey and desk-based studies are then used to describe the existing environment against which the potential direct and indirect, positive and negative impacts of the proposed project will be assessed. A key conclusion of this activity is identification of the sensitivity of the existing environment to the proposed project. Typically, the ‘environment’ is comprised of a number of receptors, which could be habitats or even key ecosystem functions such as the ability to retain water in the case of a wetland, although individual species often become the focus of interest. The sensitivity of a receptor is a function of its capacity to accommodate change and reflects its ability to recover if it is affected. The sensitivity of the receptor is therefore quantified through a number of factors, including adaptability, tolerance, recoverability and value. The significance of a potential impact is determined by considering sensitivity against the predicted magnitude of change within a matrix (Table 1.5). Assigning magnitude generally considers the extent, duration, frequency and severity of a potential effect, and whether the change is predicted to be permanent or temporary in nature. In Table 1.5, Table 1.5  An example of an impact assessment matrix used to determine impact significance. (Reproduced from Scottish Natural Heritage 2013)

Receptor sensitivity

Magnitude of change Substantial

Moderate

Slight

Negligible/none

High

Major

Major

Moderate

Negligible/none

Medium

Major

Moderate

Minor

Negligible/none

Low

Moderate

Minor

Minor

Negligible/none

18  |  Wildlife and Wind Farms, Onshore: Potential Effects a receptor with a medium sensitivity exposed to a potential impact with a substantial magnitude of change will result in a major significant impact, be it adverse or beneficial. In the context of ecological impact assessment, CIEEM defines significance in terms of an impact (negative or positive) on the integrity of a defined site or ecosystem and/or the conservation status of habitats or species within a given geographical area (CIEEM 2006). In general, impacts of moderate or major significant are unacceptable, whereas impacts of negligible or minor significance may be tolerated. Given that an impact assessment methodology is often receptor specific, it is good policy to agree receptor-specific methodologies and definitions of significance with the regulator and stakeholders at the EIA scoping stage and describe the different methodologies employed in the Environmental Statement (ES). In addition to the potential impacts resulting from a proposed project, developers are required to consider the potential cumulative impacts with other existing and reasonable, foreseeable planned wind farm projects and other relevant anthropogenic activities. Furthermore, there is an increasing requirement for consideration of trans-boundary impacts, particularly between European member states. An important step in the project design process for a wind farm is consideration of how the proposal might be adapted through mitigating measures that reduce and/or minimise impacts of an unacceptable level. CIEEM (2006) advises that priority should be given to the avoidance of impacts at source, whether through the redesign of a project or by regulating the timing or location of activities. If it is not possible to avoid significant negative impacts, consideration should be given to ways of minimising the impacts by changes to design, timing or working practices, ideally to the point that they are no longer significant. Where any remaining (‘residual’) impact is still unacceptable, compensation may be applied. This generally involves applying measures outside the project development footprint that compensate for significant impacts within it. Examples of compensation include the creation of new bird-nesting habitat at the port of Zeebrugge, Belgium, to offset habitat loss within the footprint due to expansion of the port (Stienen et al. 2005). In practice, application of compensatory measures is avoided as it requires demonstration of the success of the measures before construction of a project, which would be likely to result in significant delays to a project’s development programme and additional development risk. As a result, there are no examples of compensation applied to permitting for a wind farm in the UK.

Application determination and award of permit Application determination is the period during which the wind farm application and its supporting EIA is considered for approval. Depending on the size of the proposed project and its location, it may be determined at a local or national level (see Table 1.3 for the UK) and the determination process will vary according to the regulatory framework in place. Award of a permit to construct a project usually includes a number of conditions that require completing (‘discharge’) before construction can commence. Such conditions usually relate to permitted development rights, notices of activity, additional information unavailable at the time of application, such as the final choice of wind turbine, detailed construction methodologies and preparation of Environmental Management Plans. Permit conditions also include any mitigation identified in the EIA to reduce residual impacts.

The nature of wind farms  | 19

Monitoring Wind farm monitoring programmes are most commonly undertaken to monitor the effectiveness of any mitigation strategies, which require discharge before construction and/ or operation can commence. However, monitoring may also be undertaken to improve our understanding of specific impacts. This is generally to address issues where there is a degree of uncertainty over the extent or significance of an impact, but where the potential impacts were not predicted to be of such significance for permitting to be refused (SNH 2009). Monitoring programmes often require collection of new data before (pre-)construction targeted to the receptors of concern, although occasionally the data collected to inform the EIA will meet this requirement. It is therefore crucial to obtain clear regulator agreement on the scope and methodology of the monitoring programme to ensure that it achieves its purpose. Monitoring is generally required for the first few years post-construction, but can be required throughout the lifetime of a project. For example, recent changes to legislation in the UK allow for lifetime monitoring of wind farms greater than 50  MW to increase the ability to detect potential longer term impacts that may take several years to become apparent. RenewableUK (2011) advises that the design of the monitoring programmes should ensure clear linkages between pre- and post-construction monitoring phases, and ensure suitability for validating the predictions made in the EIA. They further advise that the programme should include agreed ‘stage gates’ at which the monitoring outputs are reviewed under an ‘adaptive management’ plan that allows monitoring effort to adapt (usually reduce) if certain stage gates/requirements are met. Adaptive management is enabled by regular reporting and feedback to the regulator and key stakeholders. Annual and final monitoring reports are generally a permitting condition in the UK and made public by the regulator after a certain period to ensure that the results of monitoring programmes add to the knowledge and evidence base for future projects. This is an important function as it allows developers to consider this information in the development of future projects in addition to allowing for a more focused EIA. This increasing evidence base is demonstrating that appropriately located wind farms can have negligible impacts (for example, see Pearce-Higgins et al. 2012).

Concluding remarks The policy of and legislative support for wind power globally have led to the construction of wind farms in more than 90 countries and its establishment as a mainstream option for new electricity generation in many markets. Wind power provides a little more than 10% of Europe’s electricity needs because of the EU Renewable Energy Directive, and the contribution of wind power to the renewables mix in the UK was more than 50% in 2014. Looking forward, it is estimated that wind power could supply 19% of global energy requirements by 2030. However, for this potential to be realised, there needs to be continued political support and policy in place. Pledges of significant commitments to reducing GHG emissions made in the ‘Paris Agreement’ at the United Nations Conference on Climate Change in December 2015 (Box 1.1) suggest that this could become a reality. In contrast, however, the renewables industry and wind power in particular has shown a period of contraction in the past few years, in some markets at least. In Europe, 2014 saw a decrease in rates of wind farm installations of between 75% and 90% in Denmark, Spain and Italy (EWEA 2015), which is affecting investor confidence. Taking the UK as an example, this is not surprising given the lack of political support in the past few years, highlighted by

20  |  Wildlife and Wind Farms, Onshore: Potential Effects the government announcement in 2015 of the end to subsidies for onshore wind and solar projects (Wintour & Vaughan 2015). In parallel with the need for strong political support, there is also a clear need for wind farm developers and the supply chain to work together in finding further cost-reduction solutions to increase the parity of onshore wind with ‘traditional’ energy generation, and thus, reduce reliance on subsidies while increasing investor confidence. The choice of turbine types continues to expand with advances in turbine technology, although the basic principle of generating electrical energy from the kinetic energy in the wind remains unchanged. Moreover, while large three-bladed HAWTs seem likely to continue to dominate commercial wind farms, the role of small to medium-sized turbines provides further options for domestic and rural application. The increasing deployment of VAWTs, particularly in urban environments, is also expected. In addition to reviewing the global policies driving renewables energy and the statutory requirements for their permitting, this chapter has drawn out the need for EIA to address continuing potential impacts on some wildlife groups such as birds and bats. While development of a more robust evidence base is important to ensure that the predictions made in the EIA are correct, it would also reduce the number of projects refused consent or delayed over potential environmental concerns by providing developers, and their regulators, with an opportunity to focus on the key issues and identify suitable mitigation. This, in turn, is likely to reduce development costs and risks, increasing the potential for parity with other forms of energy production and investor confidence. Finally, the importance of good site selection is identified as a key process in mitigating potential impacts on wildlife and the permitting process in general. It is recommended that local and national regulators support this process by preparing strategic locational guidance to assist wind farm developers in selecting appropriate areas where the inclusion of a wind farm may be tolerable.

Acknowledgements Sincere thanks to Renewable Energy Systems Limited (RES) and Nick Bristow for kindly providing photographic material. Thanks also to Ed Frost and Dan Bacon of RES and Dr Cherelyn Vella for their invaluable technical input and review.

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7 December 2015 from http://www.renewableuk.com/en/publications/guides.cfm/gyop1 RenewableUK (2011) Consenting lessons learned. An offshore wind industry review of past concerns, lessons learned and future challenges. London: RenewableUK. Retrieved 29 November 2015 from: http://www.renewableuk.com/en/publications/index.cfm/ Offshore-Wind-Consenting-Lessons-Learned RenewableUK (2014a) Small and medium wind strategy. the current and future potential of the sub-500 kW wind industry in the UK. November 2014. London: RenewableUK. Retrieved 7 December 2015 from http://www. renewableuk.com/en/publications/index.cfm/ Small-and-Medium-Wind-Strategy-report-2014 RenewableUK (2014b) Wind energy in the UK. State of the industry report 2014. October 2014. London: RenewableUK. Retrieved 7 December 2015 from http://www.renewableuk.com/en/publications/ reports.cfm/state-of-industry-report-2014 RenewableUK (2015a) Small to medium wind. Retrieved 18 March 2015 from http://www. renewableuk.com/en/renewable-energy/windenergy/small-and-medium-scale-wind/index. cfm RenewableUK (2015b) Wind energy in the UK. State of the industry report summary 2015. October 2015. London: RenewableUK. Retrieved 29 November 2015 from http://www.renewableuk.com/en/publications/reports.cfm/ state-of-the-industry-report-2015 Renewable Energy Policy Network for the 21st Century (REN21) (2015) Renewables 2015 global status report. Key findings report. Paris: Renewable Energy Policy Network for the 21st Century. Rydell, J., Engström, H., Hedenström, A., KyedLarsen, J., Pettersson, J. & Green, M. (2012) The effect of wind power on birds and bats: a synthesis report. Report 6511. Stockholm: Swedish Environmental Protection Agency. Salvador, N.N.B., Glasson, J. & Piper, J.M. (2000) Cleaner production and environmental impact assessment; a UK perspective. Journal of Cleaner Production 8: 127–132. Scottish Natural Heritage (2002) Strategic location guidance for onshore wind farms in respect of the natural environment. Policy Statement No. 02/02, Update March 2009. Perth: Scottish Natural Heritage. Retrieved 29 November 2015 from http://www.snh.gov.uk/docs/A247182.pdf Scottish Natural Heritage (2009) Guidance note, monitoring the impact of onshore wind farms

The nature of wind farms  | 23 on birds, January 2009. Perth: Scottish Natural Heritage. Retrieved 4 December 2015 from http://www.snh.gov.uk/planning-and-development/renewable-energy/onshore-wind/ windfarm-impacts-on-birds-guidance/ Scottish Natural Heritage (2013) A handbook on environmental impact assessment. guidance for competent authorities, consultees and others involved in the environmental impact assessment process in scotland. Natural Heritage Management, 4th edn. Perth: Scottish Natural Heritage. Retrieved 29 November 2015 from http://www.snh.gov.uk/docs/A1198363.pdf Stern, N (2007) The Economics of Climate Change: The Stern Review. Cambridge: Cambridge University Press. Stienen, W.M., Courtens, W., van de Walle, M., van Waeyenberge, J. & Kuijken, E. (2005) Harbouring nature: port development and ­ dynamic birds provide clues for conservation. In Herrier, J.-L., Mees, J., Salman, A., Seys, J., Van Nieuwenhuyse, H. & Dobbelaere, I. (eds) Proceedings Dunes and Estuaries 2005 Inter­national Conference on Nature Restoration Practices in European Coastal Habitats, Koksijde, Belgium, 19–23 September 2005. VLIZ Special Pub­ lication 19. pp. 381–392. Retrieved 10 March 2016 from http://ec.europa.eu/environment/life/project/ Projects/index.cfm?fuseaction=home.show​ File&rep=file&fil=LIFE02_NAT_B_008591_ Seminar.pdf United Nations Framework Convention on Climate Change (UNFCCC) (2015a, 24 March) Kyoto Protocol. United Nations Framework Convention on Climate Change. Retrieved 24 March 2015 from http://unfccc.int/kyoto_protocol/ items/2830.php United Nations Framework Convention on Climate Change (UNFCCC) (2015b, 12 December) Historic Paris Agreement on Climate Change, 195 nations set path to keep temperature rise well below 2 degrees Celsius. United Nations Framework Convention on Climate Change.

Retrieved 13 December 2015 from http://newsroom.unfccc.int/unfccc-newsroom/finale-cop21/ United States Department of Energy (2015) Utilityscale land-based 80-meter wind maps. United States Department of Energy. Retrieved 29 November 2015 from http://apps2.eere.energy. gov/wind/windexchange/wind_maps.asp United States Fish and Wildlife Service (USFWS) (2012) United States Fish and Wildlife Service, land-based wind energy guidelines, 23 March 2012. Washington DC: USFWS. Retrieved 29 November 2015 from http://www.fws.gov/ ecological-services/es-library/pdfs/WEG_final. pdf Wind Energy Foundation (2015) History of wind energy. Retrieved 7 December 2015 from http:// windenergyfoundation.org/about-wind-energy/ history/ Wintour, P. & Vaughan, A. (2015, 18 June) Tories to end onshore windfarm subsidies in 2016. The Guardian. Retrieved 29 November 2015 from http://www. theguardian.com/environment/2015/jun/18/ tories-end-onshore-windfarm-subsidies-2016 World Wind Energy Association (WWEA) (2014) Small wind world report. March 2014. Retrieved 20 March 2015 from http://small-wind.org/ wp-content/uploads/2014/03/2014_SWWR_ summary_web.pdf World Wind Energy Association (WWEA) (2015, 5 February) New record in worldwide wind installations. World Wind Energy Association. Retrieved 2 April 2015 from http://www.wwindea.org/ new-record-in-worldwide-wind-installations/ Zindler, E. (2015, 5 October) Wind and solar boost cost-competitiveness versus fossil fuels. Bloomberg New Energy Finance. Retrieved 29 November 2015 from http://about.bnef.com/ press-releases/wind-solar-boost-cost-competitiveness-versus-fossil-fuels/

CHAPTER 2

Climate EUGENE S. TAKLE

Summary This chapter examines how a collection of wind turbines in a defined region may create meteorological conditions different enough from its surroundings to change the structure and function of above- or below-ground ecosystems. Despite the rapid expansion in the number of wind farms, there are very few in situ measurements from which to establish the aerodynamic and thermodynamic characteristics, that is the microclimate, of wind farms. Consequently, conceptual models from analogues in natural or humanconstructed landscapes were needed to guide thinking about the ways in which wind farms may influence ecosystems. Wind tunnel simulations of wind farms provide insight on the changes in aerodynamic (e.g. wind speed, turbulence) characteristics of wind farms. Analysis of field measurements taken within wind farms and leeward of agricultural shelterbelts provides thermodynamic (e.g. heating/cooling, evaporation/condensation, solar and infrared radiation) characteristics needed to construct an ‘informed conceptual model’ of how turbines may affect plant functioning. Measurements show that within wind farms, turbines create night-time warming of about 1ºC and daytime cooling of less than 1ºC. Satellite measurements of surface radiating conditions provide spatial maps of surface temperature that generally agree with point surface measurements within wind farms. Carbon dioxide flux measurements in a wind farm suggest that turbines promote carbon uptake by plants during the day and increase plant respiration at night. Published studies on the regional and global impacts of large wind farms show that such effects are small as compared to, say, changes that would create measurable effects on crop yield. Global models give some evidence that large continental wind farms may create non-local climate effects, such as small changes in precipitation over oceans. More studies are needed on microclimate changes within a few hundred metres of turbines and also on whether large wind farms create regional changes in cloudiness and precipitation.

Climate  | 25

Introduction Climate can be defined as the collection of time-averaged meteorological conditions. A microclimate is the collection of aerodynamic and thermodynamic conditions describing an arbitrarily small region that differs from the surrounding larger region. This small region may consist of only a few square metres that are strongly influenced by some natural or artificial structure. The area under a tree in a meadow, for instance, would have its own microclimate as a result of average meteorological conditions different from those of the surrounding treeless meadow. On the other hand, the entire 1 km square meadow surrounded by mountains would have a microclimate different from the surrounding 1,000 square kilometre mountain region. On an even larger scale, major cities have their own urban microclimates. Microclimate is described by the averages of temperature, humidity, pressure, precipitation, wind conditions, solar and infrared radiation, and cloudiness taken on a variety of timescales such as annual, seasonal, monthly, daily or hourly. Microclimate may also include near-surface atmospheric conditions such as carbon dioxide (CO2) level and concentrations of ozone, volatile organic compounds or other trace gas concentrations, and soil conditions such as soil moisture and soil temperature. Rates of change of physical properties are also used to describe a microclimate. Heat flux, for instance, provides a measure of the rate at which heat energy enters or leaves the region. The fluxes of moisture, visible and infrared radiation, CO2 and ozone have analogous definitions. Momentum flux downwards is the process by which the momentum of air is transferred to the momentum of solid objects, such as plant parts and soil particles, or liquid surfaces, such as through the generation of ocean waves. Atmospheric turbulence is a major factor regulating most fluxes. The characteristics of a microclimate are highly dependent on the region’s exposure to large-scale weather systems as well as the characteristics of its soil, vegetation (type, height, diversity, root structure, etc.) and geology, surface slope and orientation to the sun, and proximity to water bodies, major terrain features and nearby artificial structures. Management by humans and the impact of fauna such as grazers, from large mammals to insects, may also affect microclimate conditions. Energy and moisture balance at the surface depends on the diurnal (day to night) changes in thermal stratification, or thermal stability, of the surface layer of the atmosphere. The daily cycle of heating and cooling at the earth’s surface in response to solar radiation during the day and outgoing infrared radiation during both day and night creates changes in thermal stratification in the lowest several hundred metres of the atmosphere. Thermal influences create turbulence during strong daytime surface heating and suppress turbulence when surface cooling dominates over incoming energy at night. The aerodynamic effects of wind turbines on ecosystems are determined by how the effects of rotating blades, typically 40–120 m above the surface, are mediated to the vegetation layer that is typically the lowest 1–10 m above the ground. The discussion of turbine wakes includes rotor-layer wind speed and turbulence conditions, rotational characteristics of wakes, tip vortices, propagation of wake disturbances down to the surface and ultimate dissipation of wake effects. As a bluff body, an operating turbine represents an obstacle to the airflow, which creates regions of high and low pressure within the wind farm that modify winds and surface fluxes. The operational status of a wind farm varies with wind conditions and management decisions and therefore will not have a uniform and continuous influence on the ecosystems within the wind farm. Changes in wind speed, wind direction, turbulence, shading, pressure fluctuations and generation of sound waves

26  |  Wildlife and Wind Farms, Onshore: Potential Effects will influence the effect of turbines on plant and ecosystem function. As indicated earlier, turbulence and its influence on fluxes of moisture, heat, momentum, CO2 and trace gases will be a major focus of any investigation of influential factors. Conceptual models of how turbines influence their environment must be verified and refined through measurements made in actual wind farms. A full understanding of microclimate conditions in wind farms would ideally require in situ measurements of wind speed, turbulence, temperature, humidity, carbon dioxide and pressure within operating wind farms. However, temperature measurements made remotely from satellites and on the ground in the vicinity of wind farms can provide initial insight on the collective influence of turbines in wind farm configurations. Changes in surface conditions at one part of the globe are known to occasionally create changes in distant regions (Lorenz 1979). Modelling studies help to reveal physical processes and possible locations of such ‘teleconnections’, as was shown for the influence of tropical deforestation on mid-latitude rainfall (Avissar & Werth 2005; Hasler et al. 2009). There is speculation that large collections of dozens to hundreds of thousands of turbines may influence mesoscale atmospheric processes, that is, processes such as cloudiness or precipitation patterns on the scale of a European country or a state within the USA. A full understanding of three-dimensional physical processes in a wind farm requires a computational fluid dynamics model with capabilities for simulating both the aerodynamics and thermodynamics of the region within and outside the wind farm. Such models resolve fine scales of motion when airflow interacts with turbines and realistically simulates the turbine-generated turbulence as it moves downstream to interact with other turbines and surface-based ecosystems. Experimental versions of such models are now being developed (e.g. Mirocha et al. 2015).

Scope The aim of this chapter was to build a conceptual model to describe the physical processes that allow wind farms to create their own microclimates. However, a systematic survey of the available published literature revealed that in situ wind farm measurements of microclimate have been made at only one location: a central Iowa wind farm (Rajewski et al. 2013; 2014). Other relevant studies include a few on-the-ground studies conducted in the near vicinity of wind farms, involving wind and temperature measurements in the prevailing upwind and downwind directions relative to the wind farm being studied. In most of these studies key factors affecting the wind farm microclimate were not reported. Examples include whether turbines were operating at full power, zero power or something between, and whether agricultural or other land-use operations such as grazing, irrigation and vegetation management activities that potentially would impact temperature, moisture or CO2 changes were being conducted during the measurement period. A second category of wind farm climate studies includes analyses of satellite images taken at specific times of day that provide a snapshot of surface radiating temperature conditions from areas covered by wind farms. A third type of study that has relevance to wind farm microclimate conditions is modelling of wind farms through the use of numerical models and wind tunnels. These studies provide important insight into physical processes within wind farms that are introduced or modified by turbines. They also serve as a guide for where to make in situ measurements. Also among the numerical modelling studies are simulations of how wind farms may affect regions outside wind farm boundaries and even on a global scale. Unfortunately, no studies are yet available that report the measurement of ecosystem function or structure, such as the rate of photosynthesis, biomass

Climate  | 27 accumulation or species composition. Rajewski et al. (2013) provide the only available in situ simultaneous measurements inside and outside wind farms of carbon exchanges between the atmosphere and the vegetated surfaces, but even these studies do not include the important contribution of soil processes within wind farms. The relevant thermodynamic and aerodynamic processes that turbines will influence are described within the themes in the next section, and past research on agricultural shelterbelts is used to build a conceptual model for forming questions on the effects of wind turbines. Satellite observations of temperature impacts and measurements of microclimate changes due to wind farms will be summarised. These measurements provide a point of departure for developing models of changes to natural processes in the near vicinity of turbines, as well as regional, subcontinental and global-scale models on the impacts of wind farms.

Themes Natural physical processes Ecosystem functions are driven by the rates of exchange of radiant energy (solar and infrared radiation), thermal energy (sensible heat), water (vapour, liquid, solid), trace gases (principally CO2) and the influence of wind on plant movement. Figure 2.1 shows the basic exchanges of energy and trace gases at the surface, simplified by considering only low-growing grassy vegetation. Visible radiation reaches the earth from the sun either directly or reflected by clouds or air molecules, and is either reflected or absorbed at the surface. Upward reflected Figure 2.1  Factors contributing to conservation energy is lost to ecosystem functioning and of energy (energy balance) at the earth’s surface is therefore not considered further here. A over flat, homogeneous vegetated ­terrain. At ray of solar energy may be reflected once any given time of day or season some processes or many times within the plant canopy (a­rrows) will be absent and some may be positive of an ecosystem. The density of plant in the opposite direction. parts governs the rate at which energy is absorbed as a function of depth into the canopy. Leaf area index (LAI), the one-sided plant leaf area per unit ground area, is frequently used as a vegetation metric. The area density of upper leaves affects the photosynthetic capacity of lower leaves and smaller plants at the canopy floor. Absorbed visible light is partitioned between photosynthetic processes and sensible heat content of the absorbing surface, including leaves, stems and soil. Of key relevance to a conceptual model of wind farm effects is the fate of the solar radiation that is converted to sensible heat. The absorbing surface warms and responds by: (1) radiating some energy away from the surface at infrared wavelengths, (2) conducting some energy to the air above or solid surface below, and (3) evaporating or transpiring water to the air. The latter includes loss of water when the surface is wet from rain or dew and loss of water through

28  |  Wildlife and Wind Farms, Onshore: Potential Effects plant stomata. These processes are combined into the term ‘evapotranspiration’, frequently referred to as ET. Energy and water transferred to the atmosphere change the air density and contribute to the buoyancy and turbulence of the atmosphere. Infrared radiation at the surface will be either incoming or outgoing depending on whether the surface is colder or warmer, respectively, than the air. The rate at which water is lost from the surface through evapotranspiration is strongly influenced by surface temperature and the mean and turbulent wind speeds in the vicinity of the surface, with higher values leading to higher rates of evapotranspiration. The rate of sensible heat conduction from the surface to the atmosphere similarly depends on mean and turbulent wind. Wind also affects plant growth and structure, as well as ecosystem function. Diurnal changes in the energy balance from mainly incoming during the day to mainly outgoing at night cause the temperature gradient between surface and atmosphere to reverse from negative (downward) during the day to positive (upward) at night. Heat flow by conduction and thermal diffusion is in the opposite direction to the temperature gradient. During the day a warm surface under cooler air creates convection, which generates turbulence and enhances sensible heat and moisture loss from the surface. The transition from day to night launches a thermally stable atmospheric condition that suppresses turbulence and vertical exchange of heat, moisture and momentum. At night, a cool surface under warm air suppresses convection, which slows the rate of heat gain from the overlying atmosphere and creates a downward transfer of moisture to the surface as dew. This stable layer deepens through the night to elevations typically well above the tops of turbine blades. The transition from night to day initiates weak convection very near the surface that strengthens through the day to form a deep layer of 1 km or more that efficiently mixes moisture and heat from the surface throughout its entire depth. Diurnal changes in thermal stratification have major influences on how turbine wakes interact with ecosystems within wind farms owing to their control on turbulence levels.

A conceptual model of changes caused by turbines Mean kinetic energy of the wind is transformed to mechanical energy of moving turbine blades and ultimately to electrical energy. Turbulent motions, created as a by-product of the conversion of mean energy, gradually diminish in magnitude with time and distance from their origin at the turbine blades. Higher wind-speed air overlying the wind farm is gradually diffused downwards by turbulence to increase the mean wind speed behind a turbine to its upwind, undisturbed level (Porté-Agel et al. 2014). Analogous to a clump of trees in a meadow, a wind farm creates its own ‘bubble’ of meteorological influence, or in other words it creates its own microclimate. As a bluff body, an operating turbine represents an obstacle to the flow, which creates regions of high and low pressure within the wind farm that influence winds and surface fluxes. A steady wind establishes a static (standing) pressure wave with its maximum immediately upwind and minimum immediately downwind of a turbine. Motions of the blades through a sheared wind profile and past a stationary turbine pedestal create fluctuations superimposed on this standing pressure wave that create a pumping action across the soil surface (Takle et al. 2004), leading to enhanced soil respiration and drying, with consequences for soil ecosystems. Utility-scale wind farms are not fully operational at rated capacity at all times. At wind speeds below about 4 metres per second, a typical cut-in speed, turbines do not operate at all. From cut-in speed to rated speed, typically about 12 metres per second, turbines operate with blades pitched to have maximum cross-section to the wind to increase the

Climate  | 29 wind energy captured. Above rated speed, turbine pitch is reduced to keep the power generated at the rated value. Wind farms typically operate at 30–40% of nameplate capacity over the course of a year. Curtailment of all or parts of a wind farm occurs as a result of electric grid requirements, scheduled and unscheduled maintenance, transmission line upgrades and severe storms in the vicinity. Ambient wind speeds can also fall below turbine cut-in values over all or portions of the wind farm. Without knowledge of these factors it is not possible to determine with certainty the proportion of any microclimate changes that can be attributed to turbine-generated changes as opposed to terrain effects, land use such as grazing, irrigation, cropping types or patterns, or variations in soil types or soil moisture. The conceptual model of wind turbine wakes and their modification of natural turbulent processes to create their own microclimates leads to speculation on how wind farms may influence normal ecosystem function and structure. Simply put, vegetation within a wind farm will experience a decreased mean wind speed and increased turbulence, which influences the rates of exchange of heat, water and, by extension, CO2 from the surface (Figure 2.2).

Figure 2.2  Conceptual model of turbine–crop interaction via mean wind and turbulence fields. The wake of a wind turbine consists of a cone of reduced mean wind speed extending downwind a distance of tens of H, where H is the hub height of the turbine. Within this cone there is more turbulence than outside. Both the reduction in wind speed and enhanced turbulence levels diminish with distance downwind. At a point downwind, depending on atmospheric thermal stratification, the wind conditions recover to ambient levels similar to those upwind of the turbine. During daytime the turbine wake will reach the surface closer to the tower than at night because the ambient turbulence mixes the atmosphere more effectively during the day. Turbulent motions from wind turbines can influence surface fluxes of heat, moisture and trace gases such as carbon dioxide.

How might such changes in mean wind speed and turbulence affect ecosystems within and around wind farms? Plants tend to adjust their growth to adapt to local wind conditions, as shown by ‘flagging’ of trees, where branches and leaves or needles grow and thrive on downwind rather than upwind branches, and, where plants are subject to frequent movement, the development of stronger stems to preserve plant function and prevent damage. Movement of plants tends to allow light to penetrate deeper into plant canopies, thereby allowing lower leaves and needles to support increased photosynthesis. Understorey plants also may receive more total daily solar radiation if taller plants are in motion. It is conceivable that such changes could favour some plants more than others in a balanced ecosystem. But what evidence is available in the peer-reviewed literature that supports this conceptual model?

Measured effects of turbines on ecosystem temperature Although the research literature includes numerous studies of the aerodynamic effects of wind turbines on wind speed and turbulence, studies on the influences of wind turbines

30  |  Wildlife and Wind Farms, Onshore: Potential Effects or wind farms on microclimate effects in wind farms are very limited. Indeed, the only studies that report the influence of wind farms on temperature from in situ measurements are the studies of Baidya Roy and Traiteur (2010), Smith et al. (2013) and Rajewski et al. (2013; 2014). However, the latter are the only reports up to now of microclimate concurrent in situ conditions inside as well as outside wind farms during known operational periods (see Measured effects of turbines on microclimate processes, below). The first two studies provide measurements only at points upwind and downwind of the wind farm and cite no observations inside the wind farms. For example, Baidya Roy and Traiteur (2010) provide data from a meteorological field campaign that consisted of near-surface temperature measurements taken upwind and downwind of a wind farm in California for 53 days during the summer of 1989. The results show significantly lower temperature at 5  m height at the downwind location from about 13:00 to 21:00 local standard time (LST) and slightly warmer temperatures occasionally between 01:00 and 07:00 LST at the downwind station compared to the location upwind of the wind farm. The maximum difference (cooling) attributed to the wind farm of about 3.6ºC occurred at 13:00 LST and maximum warming was less than 1ºC at about 02:00 LST. Similarly, Smith et al. (2013) report temperature measurements taken south-west and north-east of a large wind farm in the Midwest region of the USA during a 48-day period in spring 2012. No observable impact was reported for daytime vertical potential temperature gradients within 2 km of the boundary of the wind farm. However, night-time warming of 1.6–1.9ºC at 2.5 m above the surface was attributed to the wind farm. Wider scale studies of regional and global impacts of wind farms are mostly limited to reports of remotely sensed nearby surface temperature differences and modelling studies of regional and global weather patterns attributable to wind farms. For example, satellitebased remotely sensed surface radiating temperatures in regions containing wind farms are reported by Zhou et al. (2012) for west central Texas, Walsh-Thomas et al. (2012) for the much smaller San Gorgonia Pass wind farm in California and Harris et al. (2014) over Iowa. The study by Zhou et al. (2012) over the period 2003–2011 was conducted in an area where four of the world’s largest wind farms are located. The land surface temperature reported was derived from surface emission and was closely related to land surface radiative properties. A statistically significant temperature difference of about 1ºC within the wind farm compared to surrounding regions at night (22:30 and 01:30 LST) was found, but warming during the daytime (10:30 and 13:30 LST) was much weaker. Zhou et al. (2012) also reported satellite measurements of a statistically significant night-time warming trend of up to 0.72ºC per decade over the years that the wind farm was built, compared to surrounding regions with no wind farms. In a follow-on paper, Zhou et al. (2013) reported seasonal land surface temperature anomalies for the same Texas location and times as the previous paper, derived from moderate-resolution imaging spectroradiometer (MODIS) data from the Terra and Aqua satellites. In this paper, they found a warming effect of 0.31–0.70ºC during night-time for the nine-year period in all seasons, although the warming was larger in summer than spring and autumn (fall). Consistent with their earlier study, daytime temperature changes were within the level of background noise in the data. Harris et al. (2014) applied the satellite-based measurement method reported by Zhou et al. (2012; 2013) to five wind farms in Iowa. They compared night-time (22:30 LST) wind farm land surface temperature anomalies (differences from outside the wind farm) after wind farm construction with pre-construction anomalies in all seasons for the period 2003–2013. In all wind farms, a summer-time relative warming effect of 0.12–0.44ºC in June, July and August that was spatially collocated with the turbines was observed. Results aggregated over spring and autumn revealed similar results, but winter plots had high uncertainty and essentially no anomaly in the land surface temperature. In addition, the

Climate  | 31 night-time (22:30 LST) warming signal from the wind farm was strongest in summer and also in the centre of the wind farms, with weaker warming towards the edges. When Harris et al. (2014) examined changes at times other than 22:30 LST they found, in contrast to the results of Zhou et al. (2012; 2013) in Texas, that Iowa wind farms showed no cooling during the daytime. The night-time warming at 01:30 LST was weaker than earlier in the evening (22:30 LST), supporting an interpretation that, rather than warming the land surface, wind farms are simply suppressing the normal nocturnal cooling earlier in the evening, more so than later at night. Walsh-Thomas et al. (2012) used data from the Landsat 5 Thematic Mapper to measure 09:45 LST land surface temperatures upwind and downwind of the San Gorgonio Pass wind farm for summer and winter episodes from 1984 to 2011. The Thematic Mapper provided data with 240 km resolution, compared to the 1 km resolution data of MODIS. Radiating temperatures downwind (some reaching 50ºC) were higher than concurrent values upwind. However, the complexity of the terrain, unreported wind direction at hub height and operational status of the turbines during the periods of satellite images limited the ability of the study to attribute the observed surface warming to the operation of the wind turbines. Despite some differences between studies, in summary, both empirical measurements and modelling suggest that wind farms may modify temperatures enough to be of relevance to ecosystem functioning.

Measured effects of turbines on microclimate processes Measuring the effects of turbines on microclimate and hence ecosystem functioning requires measurements of the factors described in Figure 2.1 and Figure 2.2. Such measurements are made with flux stations, as shown in Figure 2.3. A caveat in all the studies described in the previous section is that none reported in situ measurements of microclimate (even in situ air temperatures) within wind farms when crops or other plant communities were known to be growing and turbines were known to be operating. Based on discussions with agronomists, Takle (2012) (website cited by Armstrong et al. 2014) itemised a list of potential impacts that turbines could have on crops, and specifically identified daytime maximum temperatures, night-time temperatures, evaporation (moisture fluxes), CO2 fluxes, pressure pumping of CO2 from the soil, plant movement (momentum fluxes) and

Figure 2.3  Flux measurement station (left), with further detail of the sonic anemometer for measuring turbulence in three dimensions (right). In the case of Rajewski et al. (2013), turbulent fluctuations of the wind were calculated from measurements, taken 20 times per second, of the difference in sound-wave travel time between each pair of ports of the sonic anemometer.

32  |  Wildlife and Wind Farms, Onshore: Potential Effects Table 2.1  Potential impact of turbines on crops as suggested by informal discussions with 15 plant physiologists, soil physicists, soil chemists, plant pathologists, photosynthesis experts and extension agricultural climatologists (qualitative assessments only; data on magnitude of effects are lacking).

Potential physical effect of decreased wind and increased turbulence due to turbines

Positive physiological effect on crops

Negative physiological effect on crops

Reduced daytime maximum temperature

Avoids summer moisture stress

Suppresses early season growth

Increased night-time temperature

Extends growing season (avoids late spring freeze, avoids early autumn frost)

Increases respiration (reduces net carbon uptake by crop)

Enhanced evaporation

Reduces dew duration (reduces favourable conditions for pests and pathogens)

Accelerates moisture loss during drought (increases plant stress)

Accelerates spring soil drying (allows earlier tillage and planting); accelerates autumn crop dry-down (reduces costs for artificial drying) Enhanced carbon dioxide exchange with crop

Enhances daytime photosynthesis

Enhanced carbon dioxide pumping from soil

Enhances daytime photosynthesis, suppresses night-time plant carbon loss due to reduced respiration

Enhanced plant movement

Increases crop photosynthesis due to deeper penetration of light into the crop canopy

Enhances night-time plant carbon loss due to respiration

mesoscale surface convergence as potential microclimate and mesoscale influences of wind farms (Table 2.1). Armstrong et al. (2014) expanded on this list and broadened the consideration to encompass natural ecosystems and carbon cycling. Considering the rate of and potential for wind plant development, they argued that the current knowledge on environmental impacts of large wind and solar energy installations is incomplete. They also specifically called for field studies and modelling of both above- and below-ground components of ecosystems to quantify the impacts of wind turbines on plant–soil cycling of carbon and plant nutrients. Carbon cycling influences will be particularly important for wind farms located in regions of high soil carbon content such as moist peat bogs (Carbon Brief 2013). To attempt to answer the key question of whether these rates of exchange of heat, water and trace gases were large enough to have measurable effects on ecosystem structure and function, the Crop/Wind-energy EXperiment (CWEX) series of field experiments undertook extensive in situ microclimate measurements during the growing season within a wind farm (Rajewski et al. 2013). Surface mean and turbulent wind conditions

Climate  | 33 upwind and downwind of single turbines, a single line of turbines and multiple lines of turbines under a variety of wind speed, directions and surface stability conditions in a large utility-scale wind farm located in a vast corn field were measured and reported. Vertically pointing lidars measured profiles of wind speed and turbulence kinetic energy from 40 m to 220 m concurrently with the surface measurements. The study was able to confirm that turbines do create measurable changes in microclimate. Direct in situ measurements of fluxes upwind and downwind of lines of turbines at times when the turbines were known to be operating provided evidence that the turbines were creating an increase in the downward CO2 flux over the crop during the daytime. Their influence on latent heat flux (moisture flux) was more ambiguous, however. On the basis of their wind farm measurements and previous modelling and measurements of the aerodynamics of agricultural shelterbelts (Wang et al. 2001), Rajewski et al. (2013) proposed three mechanisms that influence surface micrometeorological conditions in the near lee, that is, within a few rotor diameters of turbines: (1) direct modification of surface microclimate by wind turbine wakes that are intersecting the surface; (2) modification of vertical wind profiles, scales of turbulence and vertical mixing between the surface and overlying boundary layer by overhead wakes that have not reached the surface; and (3) localised enhancement of mean wind speed and modifications of fluxes within a few rotor diameters downwind due to static pressure fields (high pressure upwind and low pressure downwind) around each turbine and line of turbines. Their experiments did not, however, provide measurements of plant growth and yield influences due to turbines. Rajewski et al. (2014) report on heat, moisture and CO2 flux measurements from the CWEX-10/CWEX-11 field campaigns conducted during the growing seasons of 2010 and 2011 in the same wind farms as studied by Rajewski et al. (2013). Their data taken in a Maize Zea mays field demonstrated that turbines were probably enhancing daytime CO2 flux down into the crop canopy, but also raising night-time temperature, which enhances respiration over short periods. Rajewski et al. (2014) point out that, despite the uniform appearance of the crop landscape, variability within and between fields due to Maize cultivar, soil texture and moisture content, and management techniques leads to large uncertainties in measured fluxes. Such conditions make it extremely difficult to attribute any season-long biophysical changes, and much less yield, to turbines alone. By extension, it will be even more challenging to assess the biophysical impacts of turbines in more heterogeneous ecosystems and landscapes. Rajewski et al. (2014) did, however, show that the friction velocity, that is, the frictional interaction between the atmosphere and crop, was increased by about 25–50% at night during periods when turbines were on versus when they were off. Normal stilling of the wind at night is known to reduce evaporation and allow for longer dew periods, which is favourable for many fungal diseases. The enhanced friction velocity caused by turbines at night will be likely to reduce nightly dew periods and consequently fungal growth periods in humid climates. A rare opportunity to confirm turbine influences occurred during the overnight hours of 27–28 August 2010 during CWEX-10. Early in the evening the surface heat flux leeward of the turbine line gradually became increasingly more negative at three downwind stations than at the upwind station, indicating that the atmosphere was giving heat to the surface downwind of the turbines (Figure 2.4). At approximately 23:00 LST the heat flux difference at all three downwind stations dropped to near zero, or in other words, all four stations measured essentially the same heat flux. Shortly after midnight the heat flux differences at all downwind stations returned nearly to their previous levels. Clearly, the gradually increasing loss of heat from the surface as the evening progressed was abruptly interrupted for about 72 minutes and then returned to its previous differences of heat loss.

34  |  Wildlife and Wind Farms, Onshore: Potential Effects

Figure 2.4  Measurements of the differences (downwind minus upwind) in sensible heat flux for the overnight period of 27–28 August 2010 in a large wind farm. Measurements were taken at 4.5 m above the surface in a Maize field (height 1.8 m). Station 1 was upwind of a line of turbines, and Stations 2, 3 and 4 were successively farther downwind. Station 4 reported the largest difference from Station 1. The differences all are negative, indicating that the upwind flux was larger (in this case less negative) than the downwind flux.

Documents provided by the wind farm operator revealed that the entire wind farm of 200 turbines was shut down for 72 minutes starting at 23:00, with some turbines taking longer than others to slow to a halt (Figure 2.4). The cross-wind turbulence spectrum showed a 30% decrease in the peak intensity at the downwind stations when the turbines were off compared to when they were on, and the downward surface heat flux was higher by 10–25 W/m2 when the turbines were operating (Figure 2.4).

Potential impacts suggested by modelling studies Wind tunnel studies have a long history of providing new insight into aerodynamic flow mechanisms that are difficult or expensive to explore in the free atmospheric boundary layer (Vermeer et al. 2003; Chamorro & Porté-Agel 2009). Wind tunnel models represent small-scale physical replicas of actual wind farm layouts that are very useful for developing an understanding of the aerodynamics of wind farms. However, until recently, wind tunnel studies of wind farms have been limited to conditions of neutral thermal stratification and therefore have not contributed to the understanding of changes in wind farm microclimates. Reports by Chamorro and Porté-Agel (2010), Markfort et al. (2012) and Zhang et al. (2013a; 2013b) extended previous thermally neutral flow simulations to include the effects of thermal stratification, including both stably stratified (by use of a cooled floor) and thermally convective (heated floor) boundary layers. These reports generally agree that the overall change in surface heat flux induced by wind farms is small. However, the rotation of the blades creates a highly asymmetric wake influence on surface heat flux, with the downward-moving half of the wake having an opposite effect from the upward-moving half. Applying this to the conceptual model in Figure 2.2 suggests that the wake will affect the microclimate heat and moisture fluxes differently on the right side of the wake compared to the left side. The field measurements of Rajewski et al. (2013;

Climate  | 35 2014) confirmed different structures in the turbulence conditions across wakes that reach the ground over a Maize field. If a wind farm had a persistent wind direction it would be plausible to expect different microclimate conditions to exist at different positions leeward of turbines. Numerical models that simulate the aerodynamics and thermodynamics of the atmosphere have provided insight on how wind farms may interact with regional and global-scale meteorological phenomena and perhaps even change the global or regional climate (Baidya Roy et al. 2004; Baidya Roy & Traiteur 2010; Baidya Roy 2011; Fiedler & Bukovsky 2011). Such models use simplistic representations of the wind farm in that they resemble forests of very tall trees with no transpiration capability and no difference in colour from the underlying surface. The aerodynamic effects of individual turbines are simulated by either an actuator disk (a permeable non-rotational obstacle to the flow) or, in the most sophisticated versions, rotating blades. In the latter models, blades individually extract mean kinetic energy from the wind and create small scales of turbulence and trailing vortices at the blade tips that resemble, with considerable detail, the aerodynamic flow features observed in wind tunnel models of turbine arrays. The most sophisticated rotating blade models are now beginning to add thermodynamic processes in the form of heating and cooling of air, as in the day–night cycle of a wind farm. Baidya Roy et al. (2004) examined the impacts of wind farms on the subcontinental scale through a model simulation of the Great Plains region in the USA. They assumed that turbines convert mean kinetic energy resolved by the model into atmospheric turbulence kinetic energy as a by-product of creating electrical energy. With a focus on summertime conditions, they found that turbines reduce winds at hub height level and enhance vertical mixing of momentum, heat and moisture. Typically, this dries the surface and reduces sensible heat flux in the model. Interaction with the surface in the model is most intense an hour or two before sunrise, at a time when the nocturnal low-level jet is strong enough to power the turbines and the surface is stably stratified from overnight cooling. The impact on evapotranspiration is judged to be small, although no mention is made of the vegetation type specified in the model for the growing period they simulated. Neil Kelley of the National Renewable Energy Laboratory (Kelley et al. 2004) collected temperature and heat flux data from meteorological towers upwind and downwind of a wind farm in the San Gorgonio Pass in California that were later studied by Walsh-Thomas et al. (2012). The temperature data subsequently analysed and presented by Baidya Roy and Traiteur (2010) provided the first known surface-based microclimate measurements of temperature in the vicinity of a wind farm. A strong cooling effect during the day of nearly 4ºC from an upwind temperature of 38ºC was reported. Baidya Roy and Traiteur (2010) then used a regional model to simulate the impact of near-surface lapse rates, hubheight wind speeds, turbulence kinetic energy and energy dissipation on near-surface temperature in the wind farm. It is noted, however, that no measurements were obtained from inside the wind farm and no information is given about differences in surface, soil or vegetation conditions within compared to outside the wind farm, which may have contributed to heating and cooling differences. Baidya Roy (2011) extended the modelling work of Baidya Roy and Traiteur (2010) by use of a regional model incorporating a rotor parameterisation to study the possible impacts of wind farms on local near-surface air temperature and humidity as well as surface sensible and latent heat fluxes. The directions of the fluxes depend on the static stability and total water mixing ratio lapse rates of the atmosphere. Notably, Baidya Roy (2011) showed that simulated wind farm impacts on temperature and humidity can persist for approximately 20 km downwind.

36  |  Wildlife and Wind Farms, Onshore: Potential Effects Fiedler and Bukovsky (2011) explored the potential climatic impact of wind farms on rainfall in another modelling exercise. They found that a hypothetical wind farm covering the Great Plains in the USA would affect climate by enhancing warm-season rainfall by about 1% in the near vicinity and several tens of kilometres downwind of such a wind farm. They discuss how smaller wind farms could have large, but isolated-in-space-andtime precipitation consequences due to the ‘butterfly effect’ (Lorenz 1979), a mathematical possibility for a non-linear system. However, they point out that such incidents would be likely to have inconsequential impacts on climate and hence microclimate outside the wind farm. A report by Takle et al. (2014), based on both a wind farm model and field observations, provides evidence that wind farms create horizontal flow convergence at the surface, which is a supporting ingredient for the development of cloudiness and precipitation.

Global impacts of wind farms suggested by modelling studies The first model simulation of the global impact if wind farms accounted for a high fraction of global electrical energy was provided by Keith et al. (2004). They modelled the power generation of massive wind energy deployments in North America, Europe and China, as represented by increases in the surface drag on atmospheric flow in these regions. Such an arrangement of wind farms created non-local seasonal temperature changes outside the wind farms due to regional changes in equator-to-pole heat transport. It was estimated that if 10% of electrical energy use is from wind by 2100, there may be a regional and seasonal maximum rise of 0.5ºC, but that the global rise in temperature would be far below natural and other anthropogenic changes. An alternative approach was adopted by Wang and Prinn (2010), who used a global climate model to examine potential global climate impacts of wind farms. The effect of the wind farms was introduced into the model by increasing the roughness length at the land surface, which changes the rate of extraction of kinetic energy from the mean wind. Wang and Prinn (2010) also went beyond the Keith et al. (2004) study by including an interactive global ocean. In agreement with Keith et al. (2004), Wang and Prinn (2010) found that large-scale wind plant deployment could induce changes in temperature and surface heat fluxes even outside the footprint of the wind farm. They also suggested that this leads to modifications of the global distribution of cloudiness, particularly of low clouds, as well as precipitation. Vautard et al. (2014) also used a climate model to quantify the climatic effect of a realistic wind energy development scenario on the continental scale, but with a focus on Europe, where country commitments to wind energy production call for a doubling between 2012 and 2020 to a total installed capacity of 200 GW. Overall, Vautard et al. (2014) concluded that the impact of turbines on the whole of Europe would be very small and less than natural variability. Locally, differences in temperature could reach 0.3ºC, with increases being largest in winter. Seasonal total precipitation changes due to turbines were calculated to change by a few per cent and were significant only in small, isolated regions. Impacts would not be significant during the growing season.

Concluding remarks The conceptual model presented in this chapter is the result of past research on agricultural shelterbelts and a few measurements made in and around operating wind farms, informed by relevant published results from numerical simulations of wind farms and wind tunnel

Climate  | 37 studies of wind farms. In summary, wind farms can modify ambient environmental conditions to create their own microclimates. Ignoring the influence of terrain effects, the largest influence of turbines on ambient microclimate is through reducing mean wind speed and generating turbulence. Superimposed on this general condition is a complex patchwork of regions with increases and decreases in wind speed and turbulence. Effects of turbines at the surface are amplified at night and suppressed by normally higher turbulence during daylight hours. Turbines and their wakes influence the surface microclimates through three mechanisms: (1) direct wake interaction with the surface; (2) wakes above the surface that influence surface microclimate conditions; and (3) static pressure effects created by the turbines as bluff bodies in the ambient flow field. Turbine wakes consisting of a cone of reduced wind speed and enhanced turbulence may reach the ground beyond about two rotor diameters downwind during the day but much farther downwind at night. If this turbulence propagates to the surface it can have a large influence on fluxes of moisture, heat, momentum, CO2 and other trace gases that may be of local importance. For a constant wind direction the impact of the direction of turbine blade rotation is revealed at the surface by streamwise streaks of influence extending downwind from the turbine. These streaks consist of slight enhancements of the downward vertical velocity and turbulence on the downward half of the blade rotation, and upward vertical velocity and turbulence on the upward half of the blade rotation. The intensity of these streamwise enhancements diminishes with distance, more so during daytime than night-time, but may extend 20 or more rotor diameters downwind of the base of the turbine. Vertical fluxes reflect these narrow streamwise patterns. If the wake of one turbine strikes another turbine downwind, the intensity of surface interaction increases. As wakes penetrate deeper into the wind farm a general merging of surface streaks of influence decreases wind speed and enhances surface turbulence. The orientations of the streaks will follow any change in ambient wind direction and will take on a different character as they strike, or fail to strike, downwind turbines. Deeper into the wind farm the merged influence is less dependent on changing wind direction. Available measurements of microclimates in wind farms are very limited. More studies are needed in a wider variety of wind farm locations. Furthermore, the range of microclimate changes caused by wind farms may be of more significance to some ecosystems than others. The limited measurements taken over monoculture agricultural crops in the Midwest region of the USA are unlikely to capture the impacts that may exist within a rich and heterogeneous natural ecosystem, particularly in regions that are climatically different. For instance, climates that are very dry and windy (good locations for wind farms) are prone to soil erosion and loss of vegetation, such as occurred over a wide region of the Great Plains of the USA in the 1930s. The response of landowners after that event was to plant agricultural shelterbelts – long lines of trees – to slow the wind and reduce soil loss. Ecosystems in such extreme climates would be likely to experience a highly positive effect of reduced surface wind speeds as would be expected from wind farms, according to the conceptual model.

Acknowledgements The author acknowledges many conversations with Daniel Rajewski on the field measurements, wind tunnel studies and numerical model results relating to wind farms and partial support from the Pioneer Hi-Bred Professorship in Agronomy.

38  |  Wildlife and Wind Farms, Onshore: Potential Effects

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Walsh-Thomas, J.M., Cervone, G., Agouris, P. & Manca, G. (2012) Further evidence of impacts of large-scale wind farms on land surface temperature. Renewable and Sustainable Energy Reviews 16: 6432–6437. Wang, C. & Prinn, R.G. (2010) Potential climatic impacts and reliability of very large-scale wind farms. Atmospheric Chemistry and Physics 10: 2053–2061. Wang, H., Takle, E.S. & Shen, J. (2001) Shelterbelts and windbreaks: mathematical modelling and computer simulation of turbulent flows. Annual Reviews of Fluid Mechanics 33: 549–586. Zhang, W., Markfort, C.D. & Porté-Agel, F. (2013a) Experimental study of the impact of large-scale wind farms on land–atmosphere exchanges. Environmental Research Letters 8: 015002. doi: 10.1088/1748-9326/8/1/015002. Zhang, W., Markfort, C.D. & Porté-Agel, F. (2013b) Wind-turbine wakes in a convective boundary layer: a wind-tunnel study. Boundary-Layer Meteorology 146: 161–179. Zhou, L., Tian, Y., Baidya Roy, S., Thorncroft, C., Bosart, L.F. & Hu, Y. (2012) Impacts of wind farms on land surface temperature. Nature Climate Change 2: 539–543. Zhou, L., Tian, Y., Baidya Roy, S., Dai, Y. & Chen, H. (2013) Diurnal and seasonal variations of wind farm impacts on land surface temperature over western Texas. Climate Dynamics 41: 307–326.

CHAPTER 3

Vegetation MARGARIDA R. SILVA and ISABEL PASSOS

Summary The construction of wind farms potentially threatens important natural assests, such as rare habitats and plant species. Unfortunately, there are very few specific studies on the impacts of wind farms on vegetation compared to fauna such as birds and bats, to assess the scale of the issue. As a result, the authors consulted several Environmental Impact Assessment (EIA) studies available online conducted in different countries around the world, and made a brief analysis of the negative effects on vegetation evaluated, although these were rarely the focus of the EIA. The consensus was that direct effects related to the removal of vegetation and destruction of protected plant species and indirect effects of disturbance may obviously operate during construction, but in operation, impacts may also originate from more subtle effects like the deposition of dust on vegetation and genetic pollution. The most commonly cited and potentially significant effects were then discussed in more detail using related information in the literature. It was concluded that it is not unlikely that impacts could lead to loss of biodiversity at a regional scale, particularly taking into account the effects that invasive flora can have upon native vegetation, and consequently this should not be considered as a minor detail in impact assessment. The general lack of basic information about natural features present in potential wind farm sites appears to be partly responsible for a more rigorous evaluation of effects. Owing to the uniqueness of some habitats and species and the danger that alien species pose to biodiversity, appropriate methods to minimise possible impacts must be defined and action taken with the support of appropriate monitoring. The end of construction does not necessarily mean that vegetation can readily return to its original state, and landscape restoration is often undertaken. However, careful planning must ensure this does not lead to colonisation by invasive plants and genetic pollution.

Vegetation  | 41

Introduction As the basis of ecosystems, vegetation communities reflect site-specific climatic, physiographic, edaphic and biotic features. The composition and level of development of vegetation determine the diversity of dependent sensitive flora, fauna and fungi. Thus, local biodiversity may oscillate depending on the condition and state of preservation of the vegetation. A decline in biodiversity may have consequences for ecosystem function and the ecosystem services that are provided (Balvanera et al. 2006). Hence, vegetation is of inherently high value at the ecosystem level. The ecosystem services provided by vegetation are manifold, including soil formation and retention, water cycle regulation and water retention, nutrient cycle regulation, carbon sequestration and prevention of catastrophic events, as well as the provision of resources such as wood, timber, pasture and foodstuffs such as mushrooms (European Commission 1992). Flora and vegetation also have intrinsic conservation value. According to the Red List of the International Union for Conservation of Nature (IUCN 2014), there are 10,584 threatened plant species globally, 240 of which are extinct or possibly extinct. In Europe, the Habitats Directive [European Union (EU) 1992] aims to protect over 80 habitat types and 180 higher plant species. Such species also have a unique genetic patrimony that can be useful at a commercial, medical and ethnobotanic (cultural, spiritual and ornamental) level. Wind energy is a relatively recent type of development that has undergone a marked expansion in many countries (Drewitt & Langston 2006). Despite the many environmental benefits provided by wind power, wind farms potentially threaten important natural habitats and species, particularly in areas with high wind availability such as mountains and sand dunes. A detrimental effect on endangered species and habitats may have significant consequences for biodiversity at a local or regional level (Silva et al. 2011). The impacts generated by the implementation of a wind farm are the result of specific activities that are performed in the course of the construction and/or operation phases of the project. Therefore, these actions need to be identified at an early stage of the impact assessment, leading to an accurate analysis. These activities are described in Box 3.1. A detailed analysis of the impact on endangered species and vegetation is required. Environmental Impact Assessment (EIA) is an important tool to identify the type, scale and likelihood of environmental impacts of a project as well as potential measures to minimise or avoid harm to the habitats or species of interest. A negative impact occurs when an action results in damage to or decrease in the quality of some environmental parameter. It is possible to distinguish two types of impact: (1) a direct impact from a simple cause and effect, such as habitat loss and destruction; and (2) an indirect impact resulting from a secondary reaction or part of a chain reaction, perhaps through trophic levels, such as may occur through the introduction of a novel competitor or predator (e.g. a grazer). Wind farms may conceivably produce an array of short-, medium- or long-term negative impacts. Whether the identified impacts occur and what the most significant real impacts are should be determined by the results of ecological monitoring before, during and after development. An optimised EIA process applies specific predictions and impact analyses to existing biological communities at the project site and may trigger actions to conserve flora (Bio3 2010). The EIA process allows the early identification of the most important natural features in the area of implementation of a new wind farm. This will allow developers to avoid affecting these natural assets, or at least to minimise possible impacts. Meticulous work should be done to achieve this goal, especially when the main concerns are related to important, and often inconspicuous, plant species (Figure 3.3). Despite the

42  |  Wildlife and Wind Farms, Onshore: Potential Effects

Box 3.1  Summary of wind farm activities that can lead to effects upon vegetation In general, impact assessment takes into account two main phases: construction and operation. The major activities that are generally considered to have the potential to affect vegetation are summarised in Table 3.1. Table 3.1  Major activities that occur during the construction and operation phases of a wind farm with the potential to impact upon vegetation (Mendes et al. 2002; Coelho 2007; Bio3 2012a).

Phase

Actions

Construction

Infrastructure construction: • wind turbine foundations • platform • new access • drainage • underground cable networks • substation • temporary infrastructure (shipyard, temporary storage areas) Existing access improvement Increased presence of people and vehicles on site Landscape restoration

Operation

Operation of substation Maintenance actions of wind farm infrastructure (e.g. wind turbine foundations) and associated power lines Existence of/increased traffic and human presence

The construction phase of a wind farm involves the removal of the existing vegetation and earthmoving for the construction of wind farm foundations, platforms and opening up new access, for example (Figure 3.1). In its initial phase, the construction of this type of project involves a heavy traffic of vehicles, especially large machinery (trucks, backhoes, cranes, etc.), but also the means of transporting the workers themselves. The presence of crane trucks and large-scale equipment is also required for the transport and installation of the turbines, as the pieces have large dimensions (Figure 3.2).

Figure 3.1  Example of a new access opening to a planned turbine or other infrastructure. (Bio3)

Vegetation  | 43

Figure 3.2  Examples of large machinery operating on a construction site. (Bio3)

At the end of the construction phase, landscape restoration is usually undertaken to promote a more integrated landscape. This usually consists of simple actions that favour the natural regeneration of vegetation, such as terrain modelling and spreading topsoil in the targeted areas, and sometimes includes seeding. During the operational phase several further activities are carried out. The operation of the wind turbine and substation requires the constant presence of maintenance workers, implying the frequent transit of vehicles and people into the area. The need to perform periodic maintenance in the wind farm, especially in relation to the turbines, implies the frequent presence of skilled technicians. Likewise, the maintenance of underground cable networks can necessitate frequent vegetation removal and site disturbance.

importance of vegetation, impacts on plant communities are commonly considered to be a minor problem compared to those on other groups, such as birds or bats (Silva et al. 2011). Nevertheless, significant impacts can be triggered by construction activities, especially where these have led to the removal of vegetation (deforestation) (Box 3.1). In other words, effects can persist long after the cessation of the original action. One of the main issues that make it difficult to address the occurrence and magnitude of possible impacts on flora and vegetation is a simple lack of knowledge, not only of the distribution and abundance of important species in the specific habitat location but also about ecology, phenology and ecological processes. Another difficulty relates to the fact that in EIA studies it is not always possible to conduct fieldwork in a favourable season that allows the identification of

Figure 3.3  Example of an inconspicuous plant species, Verónica (Veronica micrantha). (Bio3)

44  |  Wildlife and Wind Farms, Onshore: Potential Effects some species under study. For example, some annual species do not have vegetative parts for much of the year.

Scope This chapter summarises the negative effects of wind farm construction and operation on flora and vegetation, including both the obvious direct effects of removal during construction and the more subtle effects during operation. As far as the authors were aware, an exhaustive compilation of all the effects and actions responsible for them does not yet exist. Although a full treatment was beyond the scope of this chapter, the objective was to review and document what are thought to be the more important effects and impacts. It was hoped that this process would illuminate gaps in knowledge or data and identify major problems with impact assessment. For example, most EIAs present only a brief analysis of potential effects, frequently with just a superficial analysis of flora and vegetation, which limits researchers’ ability to quantify any impacts. To achieve these goals, the authors consulted 36 EIA studies conducted in 14 different countries from all around the world, but mainly in Europe and the Americas, that were available online (Table 3.2). Studies were conducted in the official web pages of companies (consultants), promoters (developers) and governments. The results, presented Table 3.2  List of studies consulted in a brief review of important effects and impacts upon vegetation identified in the Environmental Impact Assessment.

Site name

Country of origin

Habitat represented

Reference

Toronto Waterfront

Canada

Human-modified landscape, forest

Dillon Consulting (2000)

Parque Eólico Pinós

Spain

Scrubland

EMAT (2005)

Capital Wind Farm

Australia

Rocky ridge, woodland, pasture

New South Wales (NSW) Government (2006)

Parque Eólico Mandoegi

Spain

Forest, grassland, scrubland

ARC (2007)

Hermanville/Clearspring Wind Farm

Canada

Forest, sand dune, wetland

AMEC Environment & Infrastructure (2008)

Parque Eólico de Prados

Portugal

Scrubland, rocky outcrops

Procesl (2008).

Sierra de los Caracoles

Uruguay

Rocky ridge, woodland

UTE (2007–2008)

Berrybank Wind Farm

Australia

Plains grassland, woodland

Brett Lane & Associates (2009)

Parque Eólico Vientos Argentinos

Argentina

Grassland, scrubland

Scudelati & Asociados (2009)

Projet Éolien Montérégie

Canada

Forest, wetlands

SNC-Lavalin Environnement (2009)

Vegetation  | 45 Table 3.2 – continued

Site name

Country of origin

Habitat represented

Reference

Parc Éolien de Cabeólica

Cape Verde

Steppe, arid grassland

Banque Africaine de Développenent (2010)

Parque Eólico de Ariques

Portugal

Scrubland, rocky outcrops

Procesl (2010)

Parque Eólico Marcona

Peru

Desert, coastal vegetation

Walsh Perú (2010)

Eolonica Wind Power

Nicaragua

Forest and costal areas

Fiallos e Associados, S.A. (2011)

Parco Eolico nel Comune di Melfi

Italy

Forest, woodland, wetland

ATS Engineering (2011)

Parque Eólico Cristal

Brazil

Woodland, forest

V&Sambiental (2011)

Parque Eólico de Candeeiros 2

Portugal

Scrubland, rocky outcrops

Agripro (2011)

Blue Renewable Energy Facilities

South Africa

Scrubland

Bergwind Botanical Surveys & Tours (2012a)

Kangnas Renewable Energy Facilities

South Africa

Arid grassland

Bergwind Botanical Surveys & Tours (2012b)

Parco Eolico Borgo Val di Taro

Italy

Forest, grassland

AMBITER (2012)

Parque Eólico de Corte dos Alamos e Sobreequipamento do Parque Eólico de Guerreiros

Portugal

Forest, scrubland

Agripro (2012)

Parque Eólico de Maunça

Portugal

Scrubland, rocky outcrops

Matos, Fonseca & Associados, Bio3 (2012)

Parque Eólico de Montalegre

Portugal

Scrubland, rocky outcrops

Bio3 (2012b)

Parque Eólico del Monte Olvedo

Spain

Woodland, scrubland

Martinez (2012)

Parque Eólico El Escuchadero

Spain

Woodland, scrubland, blanket bog

FLTQ (2012)

Parque Eólico Portela do Pereiro

Portugal

Scrubland, grassland, rocky outcrops

Amb&Veritas (2012)

Parque Eólico Tres Hermanas

Peru

Desert, coastal vegetation

Walsh Perú (2012)

Annabaglish Wind Farm

UK

Peatland habitats, forest

RES Power for Good (2013)

Central Eólica Fleixeiras I

Brazil

Sand dune, forest

Ambiental (2013)

46  |  Wildlife and Wind Farms, Onshore: Potential Effects Table 3.2 – continued

Site name

Country of origin

Habitat represented

Reference

Mesgi’g Ugju’s’n Wind Farm

Canada

Forest

PESCA Environnement (2013)

Parc Éolien de Midelt

Morocco

High plain grassland

Dekra (2013)

Parque Eólico Carrugueiro II

Spain

Scrubland, grassland

Taxus (2013)

Parque Eólico de Vila Lobos

Portugal

Scrubland, rocky outcrops

Procesl (2013)

Summerside Wind Farm

Canada

Human-modified landscape, wetland

AMEC Environment & Infrastructure (2013)

Parque Eólico de Marvila II

Portugal

Forest

Strix (2014)

Parque Eólico de Torre de Moncorvo

Portugal

Forest, woodland, scrubland

Procesl (2014)

in Table 3.3, show that the most referenced effect was the direct destruction of vegetation and/or important flora populations, mentioned in almost 89% of the studies analysed. The degradation of surrounding habitats was named in 67% of the studies, whereas the proliferation of invasive species was noted in a much lower proportion of the documents (33%). Sometimes, the proliferation of invasive plants is mentioned as an effect upon fauna and the effects on native vegetation are not considered. Surprisingly, genetic pollution was one of the less referred to effects, along with soil compaction, which was mentioned in several studies, but not as an effect upon flora and vegetation (Table 3.3). Similarly, soil Table 3.3  An evaluation of negative effects in 36 international Environmental Impact Assessments related to vegetation and floral communities.

Effect Direct destruction of important habitat and flora populations • Loss of ecological processes • Habitat fragmentation

Number of references

Percentage of references

22

88.9

6

16.7

6

16.7

Degradation of important habitat and flora populations in the surrounding area

24

66.7

Proliferation of invasive alien species

12

33.3

Deposition of dust on vegetation and consequent reduction of photosynthetic rate

5

13.9

Soil compaction

4

11.1

Soil contamination

4

11.1

Genetic pollution

1

2.8

Vegetation  | 47 contamination was described in several studies, but only in four of them was it considered to have negative effects upon plant communities. A key outcome of the review was that in only 51% of studies were effects on vegetation thought likely to occur during the operational phase, and in 43% of studies they were thought to be non-existent. Moreover, the occurrence of cumulative effects was mentioned in only 50% of the studies. The list of potential negative effects is not exhaustive, as, for example, the effect of vibration caused by turbine operation on plants (Dean 2008) has previously been noted but was not mentioned in the studies reviewed. The most significant effects as also suggested by previous studies (Mendes et al. 2002; Coelho 2007; Bio3 2012a) formed the basis of the themes of the chapter, outlined below.

Themes Destruction of vegetation The construction phase involves the removal and destruction of the existing vegetation, and earthmoving for construction of the wind farm and its infrastructure (Box 3.1). Some infrastructure will remain permanently in the area, such as the wind turbines and their foundations, substation, access roads, drainage and underground cable networks. The most important actions are those involving these final structures, which lead to permanent occupation of the space. This means that vegetation will not recover in these locations, at least during the project’s lifetime (Bio3 2012a). Other infrastructure built during the construction phase, such as platforms and delivery and storage areas, is temporary. These are completely removed and usually recovered at the end of this phase, which means that they will be eventually recolonised by vegetation (Bio3 2012a). The intervention area needed for construction depends on the minimum area required to accommodate large machinery, such as large cranes and trucks. It also depends on the wide turning radius required to accommodate trucks hauling turbine blades in excess of 40  m, especially in mountainous terrain. (Arnett et al. 2007). Wind facilities can cover relatively large areas of several square kilometres, but have relatively low direct impact on the project area [Bureau of Land Management (BLM) 2005; Arnett et al. 2007]. The BLM Programmatic Environmental Impact Statement estimated that the permanent footprint of a facility is 5–10% of the site, including turbines, roads, buildings and transmission lines. Information on actual vegetation loss was estimated in a review of permitting documents for 17 facilities or those under construction (BLM 2005). The geographic context of wind farms plays a fundamental role in the levels of actual or forecast impact. Geographic variables, such as land cover and topography, are more likely than turbinespecific variables to drive levels of land transformation. For instance, tilled landscapes, despite larger distances between turbines, have lower average land transformation, while facilities in forested landscapes generally have the highest land transformation. Flat topographies have the lowest land transformation, while facilities on mesas (an elevated area of land with a flat top and sides that are usually steep cliffs), for example, have the largest (Diffendorfer & Compton 2014). Destruction of existing vegetation can lead to important habitat loss and other parallel effects, such as the loss of important ecological processes and habitat fragmentation. While the actual land-take may be comparatively limited, the effects may be more widespread where developments interfere with hydrological patterns or geomorphological processes,

48  |  Wildlife and Wind Farms, Onshore: Potential Effects for example. The ecological processes are strongly tied to the vegetation and the habitat it creates. For example, peatlands containing important or priority habitats included in EU Habitats Directive Annex 1 are particularly sensitive and can be directly damaged by in­appropriate siting of wind farms or their associated infrastructures, such as new or improved access roads (Box 3.2). Although the loss of vegetation may be relatively small, the conditions sustaining that habitat, such as high water content, may also be affected, and this can lead to indirect effects on adjacent habitats, resulting in a much larger affected area.

Box 3.2  The case of peatlands in Scotland Much blanket peat is developed over smooth ground in very windy environments, and thus offers considerable potential for wind energy conversion. The habitat spans two Habitats Directive Annex 1 types, blanket bogs and depressions on peat substrates of the Rhynchosporion, with active blanket bog listed as a priority habitat. Dargie (2004) studied information based on environmental statements submitted for planning permission and impacts of a sample of wind farms on blanket peat habitats in Scotland. Direct habitat loss and degradation occur through, for example, the excavation of peat, boulder clay or other glacial material to provide rock foundations for turbine bases. Dargie (2004) reported that for most of the excavations he studied, pumping on a daily basis was necessary, although exceptions existed for dry blanket peat types and where there had been low rainfall in the spring and early summer, which is often the period of turbine erection. Overall, it was thought that roads form the largest impact on blanket bog, including on hydrology. Floated roads will result in some compression and a probably modest change in hydraulic conductivity. Cut roads through blanket peat include a steepened upper slope, a side ditch, cross-drains at varying intervals and a zone of disturbance where water and occasional sediment is discharged. This is likely to result in drier conditions adjacent to much of the road corridor. Road design is important and substantial improvements to existing hill road types can be achieved to minimise any impacts. Moreover, indirect damage may be caused because developments have not taken sufficient account of the underlying hydrology of the peatland. So, while the actual amount of peat lost may be small, the damage caused to the natural drainage system of the peat through drainage ditches, and so on, may have repercussions over a much wider area and can ultimately lead to the deterioration of a more significant area of peatland and other related habitats, such as streams and other watercourses located downstream. Construction of a wind farm at Derrybrien in Ireland triggered a major earth movement which eventually affected 70 ha of very wet blanket bog and conifer plantation, releasing a very large volume of liquid peat into a narrow watercourse, damaging bridges, closing roads and probably eliminating the local fishery. In the future, geotechnical risk assessments are likely to be required for all wind farm developments sited on deep peat. Dargie (2004) concluded that the cumulative impacts of wind farms on blanket bog were much smaller than degrading influences such as post-World War II losses to forestry and gully erosion discussed by other authors, but should not be underestimated.

Vegetation  | 49

Figure 3.4  Example of soil compaction in a Portuguese wind farm. (Bio3)

Habitat fragmentation is often defined as a process during which a large expanse of habitat is transformed into a number of smaller patches of smaller total area, isolated from each other by a matrix of habitats, unlike the original. The negative effects of habitat loss and fragmentation on biodiversity (both flora and fauna) are well known (Wilcove et al. 1984; Fahrig 2003). One of the problems with fragmentation is the ‘edge effect’, whereby a different plant community suited to the different conditions is favoured (Wilcove et al. 1984; Fahrig 2003). A further, less well-known, indirect effect linked to the construction of wind farms is soil compaction. High levels of soil compaction are common in heavily used construction sites. Soil structure and hydrology may be altered through increasing soil bulk density; breaking down of soil aggregates; decreasing soil porosity, aeration and infiltration capacity; and increasing soil strength, water runoff and soil erosion. As a result, some physiological dysfunctions in plants can develop, such as reduced absorption of the major mineral nutrients, which can lead later to poor vegetation recovery (Kozlowski 1999) Figure 3.4). Other indirect effects may result from changes in runoff patterns and even an intensification of erosion, as well as changes in trophic equilibria due to increasing nitrogen or other nutrients.

Degradation of important habitat and flora Landscape devaluation is a patent effect that can easily be detected after construction. The infrastructure that is required to support an array of turbines such as roads and transmission lines may represent an even larger potential threat to wildlife than the turbines themselves. Most of the negative effects of wind farms on vegetation arise from the opening of roads, increased accessibility and the ‘restoration’ activities that allow the colonisation of important habitats by pioneer and synanthropic and alien species from disturbed habitats (Kuvlesky et al. 2007; Fraga et al. 2008). These are permanent effects, which will occur as long as the wind farm exists. Indirect effects linked to the opening of roads and the increase in accessibility also include the change of land use in their vicinity, the increase in grazing of important habitats, and traffic pollution causing a progressive deterioration of the environment (Fraga et al. 2008).

50  |  Wildlife and Wind Farms, Onshore: Potential Effects There have been some comprehensive studies about the indirect effects of wind farms on habitats, for example, in plant diversity. Of importance is the study by Fraga et al. (2008) on the effects of wind farms on the plant species and vegetation diversity of blanket bog on summits and slopes in the Xistral Mountains (north-west Spain), where priority habitats exist (EU Habitats Directive, code 7130: blanket bog). The original surveyed area was mainly covered by characteristic communities, which are endemic to the Xistral Mountains and usually form very homogeneous vegetation. However, alteration to the vegetation occurred within a very short period (Topić & Stančić 2006; Walker & Preston 2006; in Fraga et al. 2008), with significantly lower α diversity (differences in diversity in sites or habitats at a more local scale) and higher β diversity (differences in diversity between habitats or communities) in impacted areas compared to non-impacted areas, even 9 years after construction. They also indicated a link between the spread of synanthropic species and wind farms, which was confirmed, from a qualitative perspective, by the greater community heterogeneity found in altered patches. In the areas altered by the construction of wind farm, new communities were observed. The consequences in plant diversity alteration are wide-reaching as changes in biodiversity can influence ecosystem processes. There has been substantial debate over both the form of the relationship between species richness and ecosystem processes and the mechanisms underlying these relationships. Theoretically, rates of ecosystem processes may increase linearly with species richness if all species contribute substantially and in unique ways to a given process, that is, have complementary niches (Chapim et al. 2000).

Deposition of dust on vegetation The movement of machinery and vehicles in the construction phase and for the purposes of maintenance of individual turbines and associated infrastructure, such as substations, throughout the operational life of the wind farm causes the disturbance of dust, which will consequently accumulate on the surrounding vegetation. The intensity of dust mobilisation during the construction phase is naturally higher than in the operation phase, but may still be intense at particular times in the latter. Wind farms typically contain a network of unpaved gravel roads to provide access (Figure 3.5). The nature of the ground conditions

Figure 3.5  Mobilisation of dust from vehicle traffic along an unpaved road in a Portuguese wind farm. (Bio3)

Vegetation  | 51 (e.g. substrate type) and climatic conditions (e.g. hot and dry in the Mediterranean or cool and wet in northern Europe) will have a large effect on the issue of dust. Dust deposition may cause negative effect on vegetation, in a physical and/or chemical way. Farmer (1993) provides a comprehensive review of the effects of dust on plants and vegetation communities. It is important to understand that dust consists of solid matter in a fine state of subdivision, so that the particles are small enough to be mobilised and carried on the wind. Several characteristics of dust, including its source, particle size and chemical composition, are important in this respect and its subsequent effect. In simple terms, dust may physically smother the leaves, depending on the absolute level of deposition, which is affected by dust emission rates, meteorology and conditions on the leaf surface. Rates of dust deposition affected by factors such as surface roughness and rain. An increase in surface roughness causes a significant increase in deposition rates (Belot et al. 1976; Farmer 1993). Conversely, wet surfaces can cause increased deposition (Chamberlain et al. 1967; Farmer 1993). Thus, while rain may partially wash leaves clean of deposited dust, the resulting wet surfaces may then experience higher deposition rates. A wide variety of tree species (e.g. European Alder Alnus glutinosa, European Ash Fraxinus excelsior, Silver Birch Betula pendula and Catawba Rosebay Rhododendron catawbiense) have been studied in their response to the effects of urban road dust (Farmer 1993). The responses studied have been limited to a reduction in photosynthesis and diffuse resistance and an increase in leaf temperature, the last two effects making the tree more susceptible to drought. This may be exacerbated by the dusted leaves allowing greater penetration of road salt, which further increases water stress (Fluckiger et al. 1982; Farmer 1993). Other effects of dust from urban roads found in different species are reduced fruit set, leaf growth and starch production; increased necrosis, absorption and insolation; and blocked stomata. In relation to the physical blocking of stomata, Krajickova and Mejstrik (1984) noted that stomatal diameter is 8–12 µm for a range of crops (e.g. Maize Zea mays, Pea Pisum sativum, Barley Hordeum distichon), implying that particle size is critical if dust is to impair stomatal functions. For unpaved roads, Everett (1980) found that there was a rapid decline in particle size in the first 8 m from the road with a loss of particles greater than 50 µm in diameter. At 30 m a further decline took place, this time in particles greater than 20 µm. Similarly, Tamm and Troedsson (1955) found that beyond 20 m from an unpaved road only fine silts seemed to be deposited. From such studies, it would appear that some species may be affected more than others, depending on their stomatal size and relative to their position along a gradient from the source of dust. It is therefore not inconceivable that sufficient dust loading may drive shifts in vegetation communities alongside the roads in wind farms, thus delivering a permanent effect during the operational lifetime of the wind farm. Despite the potential for significant effects, dust mobilisation and deposition is usually considered to be a minor problem, partly as any effects of dust do not tend to manifest as an obvious visual impact. Moreover, primarily because very specific and complex studies are required to demonstrate its full effects on vegetation, dust remains poorly assessed. For example, only 5 of the 36 of the EIA studies reviewed raised the possibility of an effect. To date, the authors are unaware of specific studies or monitoring performed on dust mobilisation and deposition in relation to wind farms. This belies the fact that in the construction phase at least, any potential effect could be mitigated through periodic water spraying on unpaved gravel roads, especially in the dry season.

52  |  Wildlife and Wind Farms, Onshore: Potential Effects

Invasive plant species Invasive species such as Australian Acacia spp. (Gibson et al. 2011; Le Maitre et al. 2011) are characterised by their ability to rapidly increase abundance and distribution, typically through the production of large numbers of seeds and other propagules, with the potential to modify the character, condition, form or nature of the invaded ecosystems, causing long-lasting changes (Richardson et al. 2000). According to Delivering Alien Invasive Species Inventories for Europe (DAISIE 2008), 6,658 terrestrial plant species have been classified as alien in one part of Europe or another. Impacts of invasive plants on biodiversity can be extensive and occur at several levels, such as the alteration of soil nutrient levels, soil pH, litter decomposition rates and the hydrological cycle; and the production, abundance, diversity and behaviour of communities (Fuentes-Ramírez et al. 2010; Vilà et al. 2011). Species fitness and growth can be affected, resulting in a significant decline in native species richness (Gaertner et al. 2009). The reduction in the presence of natives resulting in direct changes in seed rain can modify the native seed bank composition (Gioria et al. 2012). Many of these effects can be persistent, as they hinder or even prevent the establishment of native species long after the removal of the invasive species (D’Antonio & Meyerson 2002; Lorenzo et al. 2010; Marchante et al. 2011). Although the spread of alien flora is one of the major impacts affecting vegetation communities and has been receiving increasing attention (Richardson & Pysek 2006; Richardson & Kluge 2008), it is commonly considered to be a minor problem during EIA and sometimes little work is done to minimise or prevent this impact (Passos et al. 2012). This understates the importance of this permanent impact, the effects of which may have serious consequences on biodiversity at local and regional levels (Le Maitre et al. 2011). In wind farms specifically, recently disturbed areas, particularly during the construction phase, may provide optimal locations for the installation and proliferation of invasive plant species (Gibson et al. 2011; Le Maitre et al. 2011) as a result of the germination of propagules accidentally introduced in topsoil from locations other than the project area, or unintentionally carried by people or vehicles. The proliferation of invasive alien plant species has often been poorly assessed (Silva et al. 2011). However, in some countries, such as Portugal, increasing awareness about invasive plants has motivated a desire to avoid or minimise the problem in the early stages of the EIA process (Box 3.3). The information gathered during early EIA stages allows the planning of future actions and the avoidance of greater problems in the future (Passos et al. 2012; 2013). In this phase it is important to establish which alien species exist in the project area and where exactly they are located. Accurate species identification and specific mapping are fundamental tools that can make a difference in curbing the spread of an invasion, as it allows control actions to be planned in advance (Passos et al. 2012; 2013; Marchante et al. 2014).

Box 3.3  Monitoring of alien flora in a wind farm in central Portugal A monitoring programme was developed in Serra da Lousã wind farm, located in a mountain area in central Portugal. Currently, this wind farm has 20 turbines distributed over about 10 km. During the Environmental Impact Assessment phase, the presence of two invasive alien species, Acacia dealbata (Figure 3.6) and Acacia ­melanoxylon, was detected within the project area and its surroundings. ­Accordingly,

Vegetation  | 53 the potential propagation of these species following construction was identified as an important negative impact, as it is known that the creation of open spaces favours the spread of alien species. A seed bank of these species was thought likely to greatly influence the evolution of the vegetation after wind farm construction. This motivated the establishment of a floral monitoring programme that began in 2006 before construction in 2009, and extended into the operational Figure 3.6  An individual of the invasive plant phase until 2013. Acacia dealbata growing in the project area The programme comprised the of the Serra da Lousã 2 wind farm in Portugal. characterisation of the area of future (Bio3) placement of wind farm infrastructure (access, turbines, substation, etc.) and the immediate surroundings. Regular systematic searches were undertaken, the location of all alien species was recorded with Global Positioning System (GPS) in the field and the number of individuals of each species was estimated (Passos et al. 2012; Bio3 2014). The data collected showed that 3 years after construction in 2009, the number of stands and the number of individuals of invasive species had increased considerably (Figure 3.7). The invasive species were observed to be spreading along the wind farm infrastructure, especially access roads and platforms (pads). New invasion sites were also found, suggesting that this increase was related to construction activity (Figure 3.6). A further two other invasive species also appeared in the wind farm area. After the monitoring, a control and eradication plan was implemented to guarantee the eradication of the invasive vegetation.

Figure 3.7  The number of individuals of the alien species Acacia dealbata and A. melanoxylon in different types of wind farm infrastructure (access roads and platforms) and overall, in different years before, during and after construction in 2009.

54  |  Wildlife and Wind Farms, Onshore: Potential Effects When invasive plants are present and potential proliferation is identified as a negative effect resulting from project implementation, action during the construction phase in cooperation with the wind farm developer is recommended, with the specific aim of avoiding the spread of invasive species. Actions include the correct disposal of plant debris, measures to prevent seed dispersal during the removal of vegetation and using only soil from non-invaded areas in recovered areas. After construction, it is important to implement a control/eradication plan and a monitoring programme in the area surrounding the project area (Box 3.3). The control will eliminate any nuclei present, limiting seed input into areas otherwise suitable for dispersion. The methods can differ according to species, although combining different methods is usually is most effective (Plantas invasoras em Portugal 2015). For example, in the case of most Acacia spp. this consists of pulling seedlings out regularly, ring barking adults or cutting them accompanied by chemical treatment (Marchante et al. 2005; Passos 2014).

Genetic pollution Genetic pollution may be caused by revegetation with different species or varieties that are not of local provenance. Simple actions that favour the natural regeneration of vegetation are usually conducted at the end of the construction phase with the aim of achieving a more integrated landscape. Commonly used actions include terrain modelling, spreading topsoil in the targeted areas and distributing seed by hydroseeding, which is a specific technique using a slurry of seed and mulch sprayed over the landscape (Figure 3.8). Standard mixtures of commercial varieties of grass species, such as Common Bent Agrostis capillaris, Creeping Bent Agrostis stolonifera and Red Fescue Festuca rubra, are commonly used. Rather than promote natural revegetation, large landscaping projects may unintentionally promote genetic contamination risk, where the species used are in close proximity to native populations, are sexually compatible with native populations, comprise wind-pollinated species and are of limited genetic diversity of clonal material from distant or unknown source populations (Rogers 2007). Genetic pollution can also be triggered by the accidental introduction and propagation of species within topsoil originating from locations other than the siting area, or even on vehicles or people from other regions as a result of increased accessibility due to the presence of new or better roads within the site. The introduction of non-local genes may ultimately affect the genetic integrity of the surrounding native populations as an indirect and permanent negative effect. Hybridisation between native and introduced individuals alters the gene pool of the native populations (Fraga et al. 2008). Some authors argue that any changes in genetic structure and their consequences should be monitored on both a short-term and a long-term basis. Unfortunately, this is not usually achieved because the impacts often outlast the period covered by the project’s EIA and Management Plan (Fraga et al. 2008). Indeed, the authors are unaware of specific studies or monitoring performed on these specific projects or in wind farms. It is also difficult to detect or even develop Figure 3.8  The application of hydroseeding in a guidelines to detect genetic contamination Portuguese wind farm (Bio3).

Vegetation  | 55 as sufficient information is rarely available, with this mostly based on neutral genetic markers and not the adaptive portions of the genome, the risk of contamination is context dependent, there are different spatial scales of adaptation for different traits, and it is difficult to determine adaptive genetic variation for threatened or endangered species (Rogers 2007).

Local changes in heat and water transfer at the soil surface Some studies have shown that the presence and operation of wind farms can cause changes in local atmospheric conditions and heat and water transfer at the soil surface (Zhou et al. 2012). The modelling study by Zhou et al. (2012) showed that wind farms could significantly affect local surface temperature by increasing surface roughness, changing the stability of the atmospheric boundary layer and enhancing turbulence in the rotor wakes. A significant warming trend of up to 0.72ºC per decade was predicted, particularly at night-time, in areas with wind farms relative to nearby areas without them. The actual effects on plant communities of atmospheric changes are still poorly understood, and as a consequence have been poorly assessed in EIA, despite the potentially permanent nature of effects during the operational phase. Moreover, studies using global and regional climate models have shown that extremely large wind farms may have strong impacts on weather and climate at these scales (Baidya Roy et al. 2004; Baidya Roy 2011). Results from studies in the USA indicate that wind farms significantly affect near-surface air temperature and humidity as well as surface sensible and latent heat fluxes that may extend a significant distance (up to 23 km) downwind from the edge in any size of wind farm (Baidya Roy et al. 2004; Baidya Roy 2011).

Cumulative and in-combination effects Cumulative effects are an important issue with regard to the assessment of impacts on vegetation. Individually, a wind farm, or indeed any activity or action, may have minor effects on the environment, but collectively these may be significant, potentially greater than the sum of the individual parts acting alone (Masden 2011). Hyder (1999) defined cumulative effects as ‘[those] that result from incremental changes caused by other past, present or reasonably foreseeable actions together with the project’, especially in local or regional areas where multiple wind farms are built over time. This issue is addressed in some EIA studies with a comprehensive analysis of existing projects, such as wind farms and other projects, in the surrounding area and a general assessment of resulting effects. Actually, according to the review conducted, almost 50% of documents analysed make this assessment, although none makes direct reference to cumulative effects on flora and vegetation. A meaningful cumulative assessment is difficult to achieve given the lack of information about existing projects on the surroundings. In-combination effects are another important issue. Although potential negative effects tend to be analysed in isolation, what is observed in reality is the combination of different effects operating at a site added together and coupled with the prospect of different effects from entirely different anthropogenic practices (e.g. clearance for agriculture, grazing by livestock) being added to a wind farm (Hyder 1999). For example, the effect of degradation can be added to the proliferation of invasive species and the destruction of different populations of an endemic or a rare species.

56  |  Wildlife and Wind Farms, Onshore: Potential Effects

Concluding remarks Impacts on vegetation are rarely the main issue in EIA. An obvious hindrance to the rigorous impact assessment is the general lack of basic information about the natural assets, even in protected areas. Outside these territories the existing knowledge base is even smaller, so when an EIA is conducted there is very little information about the area that is being studied. The lack of information on existing habitats could easily lead to superficial EIAs on the effects of the wind farm on vegetation. Although a full treatment was beyond the scope of this chapter, the objective was to review and document what are thought to be the more important effects and impacts. To achieve these goals, 36 EIA studies, conducted in 14 different countries from all around the world, were consulted. The review suggested that the EIA tends to raise a number of potentially important effects that could lead to impacts. A summary of the activities in different phases of a wind farm leading to effects and potential impacts is shown in Table 3.4. The most well-known negative effects on vegetation, caused by construction of wind farms, are essentially related to the removal of important vegetation and/or important rare plant species and the proliferation of invasive alien species (Silva et al. 2011; Passos et al. 2013). Other less obvious effects, such as degradation of important habitat and flora in the surrounding area, deposition of dust on vegetation and consequent reduction of photosynthetic rate, genetic pollution and changes in atmospheric conditions and heat and water transfer at the soil surface, are also likely to occur. There is clear scope for negative effects to lead to a loss of biodiversity on a large scale and have at least a regional dimension, and consequently they should not be considered a minor detail in impact assessment. Nevertheless, EIA tends to conclude that effects will not be significant. However, the actual significance of effects has not actually been demonstrated as, to the best of authors’ knowledge, the number of published papers that deal with the effect of wind farms on habitats, important plant species or plant biodiversity is extremely small (e.g. Lindsay & Bragg 2005; Fagúndez 2008). This is especially the case in relation to the wealth of published surveys on wind farm construction and operation effects on fauna, especially studies of bird and bat fatalities and displacement (e.g. Chamberlain et al. 2006; Drewitt & Langston 2006; Barclay et al. 2007; Hull & Muir 2010; Arnett & Baerwald 2013; Marques et al. 2014). Clearly, more in-depth monitoring of vegetation is routinely required, building on what has begun to occur in relation to the important issue of alien species in some countries such as Portugal, where monitoring has subsequently led to control (Box 3.3). In relation to mitigation, any work to mitigate the impact of alien species generally has to be done after construction is completed (Silva et al. 2011). In contrast, any impacts regarding important vegetation types and particular species of flora are generally easier to avoid or minimise in the early stages rather than relying on the restoration of habitats and species after the event. The science of restoration ecology, which attempts to better understand the process of succession and use its principles to re-establish natural terrestrial communities (Davy 2002), is becoming more important as human impacts on ecosystems are increasingly becoming more numerous and profound. Rehabilitation or restoration of disturbed areas is often undertaken in wind farm projects at the end of the construction phase and aims to minimise the impacts resulting from the implementation of the project and enable better landscape integration. Usually, simple actions that favour the natural regeneration of vegetation, such as terrain modelling, spreading topsoil in the targeted areas and sometimes distributing seed, are undertaken. If done properly, landscape restoration can have positive effects on vegetation, by accelerating the process of colonisation of

Vegetation  | 57 Table 3.4  Negative effects and potential impacts that occur during wind farm construction and operational phases and their respective responsible activities (Mendes et al. 2002; Coelho 2007; Bio3 2012a).

Phase

Activities

Effect

Impact

Construction

Infrastructure construction and/or improvement

(1) Direct destruction of important habitat and flora

Biodiversity loss Habitat fragmentation Loss of ecological processes Soil compaction Soil contamination

Increased human presence on site

(2) Degradation of important habitat and flora in the surrounding area

Community alteration

(3) Proliferation of invasive alien species

Biodiversity loss

Vegetation composition alteration Loss of ecological processes Vegetation composition alteration Loss of ecological processes

Operation

(4) Alteration of physiological processes caused by deposition of dust on vegetation

Alteration of physiological processes caused

Landscape restoration

(5) Genetic pollution

Genetic biodiversity loss

Increased human presence on site

(2) Degradation of important habitat and flora in the surrounding area

Community alteration Vegetation composition alteration Soil compaction

(3) Proliferation of invasive alien species

Biodiversity loss Vegetation composition alteration Loss of ecological processes

Operation of wind facilities

(4) Alteration of physiological processes caused by deposition of dust on vegetation

Alteration of physiological processes caused

(6) Changes in atmospheric conditions and heat and water transfer at the soil surface

Community alteration Vegetation composition alteration

58  |  Wildlife and Wind Farms, Onshore: Potential Effects the disturbed areas and thus the succession of communities, as well as possibly preventing or hindering colonisation by invasive species (Davis et al. 2000). Alternatively, landscape restoration could backfire and have serious negative effects on the surrounding ecosystems by allowing the colonisation of important habitats by pioneer and synanthropic and alien species from disturbed habitats (Kuvlesky et al. 2007; Fraga et al. 2008), and lead to genetic pollution of plant populations, thereby altering vegetation communities and their ecology. Careful consideration of the issues and the techniques that should be applied, with the support of rigorous monitoring, is clearly required in future projects.

Acknowledgements We would like to thank all those who have contributed to the text revisions. Special thanks to Bio3 and IBERWIND for the permission to use data.

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62  |  Wildlife and Wind Farms, Onshore: Potential Effects Procesl (2010) Estudo de impacte ambiental do Parque Eólico de Ariques – Relatório final. Procesl (2013) Estudo de impacte ambiental da remodelação do Parque Eólico de Vila Lobos. Procesl (2014) Estudo de impacte ambiental do Parque Eólico de Torre de Moncorvo – Relatório Síntese. RES Power for Good (2013) Annabaglish Wind Farm, Environmental statement. Volume II: Main report. Retrieved 21 December 2014 from http://www.annabaglish-windfarm.co.​u k/ media/31108/Annabaglish%20Wind%20Farm%​ 20-%20ES%20-%20Volume%201%20-%20NTS. pdf Richardson, D.M. & Kluge, R. (2008) Seed banks of invasive Australian Acacia species in South Africa: role in invasiveness and options for management. Perspectives in Plant Ecology, Evolution and Systematics 10: 161–177. Richardson, D.M. & Pysek, P. (2006) Plant invasions: merging the concepts of species invasiveness and community invisibility. Progress in Physical Geography 30: 409–431. Richardson, D.M., Pysek, P., Rejmánek, M., Barbour, M.G., Panetta, F.D. & West, C. (2000) Naturalization and invasion of alien plants: concepts and definitions. Diversity and Distributions 6: 93–107. Rogers, D.L. (2007) Planting Natives: Implications for genetic pollution. Presented at CNPS Conservation Conference, 8 September, Santa Cruz, CA. Retrieved 21 December 2014 from https://www. cnps.org/cnps/conservation/conference/2007/ rogers_genetics.pdf Scudelati & Asociados (2009) Evaluación de Impacto Ambiental Parque Eólico Vientos Argentinos. Provincia de Santa Cruz. http://www.inti.gob. ar/cirsoc/pdf/accion_viento/EIAPEVA_001_09_ SOW.pdf Silva, M., Passos, I., Bernardino, J., Costa, H. & Mascarenhas, M. (2011) Impacts on vegetation: a minor detail from a bigger problem? Unpublished poster presented at Conference on Wind Energy and Wildlife Impacts (CWW 2011). SNC-Lavalin Environnement (2009) Étude D’Impact Environnemental Parc Éolien Montérégie. Rapport Final. Retrieved 21 December 2014 from http://www.parceolienmonteregie.com/wp-content/uploads/ Etude-impact-1-de-4_v2.pdf Strix (2014) Estudo de Impacte Ambiental do Parque Eólico de Marvila II – São Mamede – Relatório Síntese.

Tamm, C. O. & Troedsson, T (1955) An example of the amounts of plant nutrients supplied to the ground in road dust. Oikos 6: 61–70. Taxus (2013) Estudio de impacto ambiental del proyecto de instalación del Parque Eólico Carrugueiro II. Municipio de Boal (Principado de Asturias). Topić, J. & Stančić, Z. (2006) Extinction of fen and bog plants and their habitats in Croatia. Biodiversity and Conservation 15: 3371–3381. UTE (2007–2008) Estudio de impacto ambiental. Parque Eólico 10MW ‘Sierra de Los Caracoles’. Administración Nacional de Usinas y Transmisiones Eletricas. Retrieved 21 December 2014 from http://portal.ute.com.uy/sites/default/files/ documents/files/institucional/GA%20EIA%20 Parque%20Eolico%20Caracoles.pdf V&Sambiental (2011) Estudo de impacto Ambiental do Complexo Eólico de Cristal. Retrieved 21 December 2014 from http://ifcextapps.ifc.org/ ifcext/spiwebsite1.nsf/0/3D046B89A31EEA328 5257C000076F3B7/$File/Relat%C3%B3rio%20 03%20-%20Parque%20E%C3%B3lico%20 Cristal%2020110608%20-%20vers%C3%A3o%20 final.pdf Vilà, M., Espinar, J., Hejda, M., Hulme, P., Jarosık, V., Maron, J., Pergl, J., Schaffner, U., Sun, Y. & Pysek P. (2011) Ecological impacts of invasive alien plants: a meta-analysis of their effects on species, communities and ecosystems. Ecology Letters 14: 702–708. Walker, K.J. & Preston, C.D. (2006) Ecological predictors of extinction risk in the flora of lowland England, UK. Biodiversity and Conservation 15: 1913–1942. Walsh Perú (2010) Estudio de impacto ambiental Parque Eólico Marcona. Walsh Perú (2012) Estudio de impacto ambiental Parque Eólico Las Tres Hermanas. Retrieved 21 December 2014 from http://idbdocs.iadb.org/ wsdocs/getdocument.aspx?docnum=38948303 Wilcove, D.S., McLellan, C.H. & Dobson, A.P. (1986) Habitat fragmentation in the temperate zone. In Soule, M.E. (ed.) Conservation Biology: The Science of Scarcity and Diversity. Sunderland, MA: Sinauer Associates. pp. 237–256. Zhou, L., Tian, Y., Roy, S.B., Thorncroft, C., Bosart, L. & Hu, Y. (2012) Impacts of wind farms on land surface temperature. Nature Climate Change 2: 539–543.

CHAPTER 4

Terrestrial invertebrates SARAH ELZAY, LUSHA TRONSTAD and MICHAEL E. DILLON

Summary Terrestrial invertebrates are often the dominant consumers and pollinators of plants, are a major food resource for birds, bats, mammals, reptiles and other invertebrates, and are critical soil engineers and detritivores. Although invertebrates are vital to ecosystems, exceptionally few published studies have investigated the potential effects of wind farms on terrestrial invertebrates. Many insects are likely to be killed by colliding with turbine blades and vehicles on wind farm access roads, but the magnitudes of these losses and their impacts on local communities have not been measured. Although these collisions may be more apparent, other aspects of wind farm development may have more pronounced effects on invertebrate communities. Constructing and operating wind farms may lead to habitat loss and fragmentation, chemical pollution and dust, noise pollution, the introduction of invasive species along access roads and changes in environmental factors. Changes in the bat and bird communities may alter the numbers and species of invertebrates at wind farms, which may cascade to lower trophic levels. Data are largely lacking on how wind farms may affect terrestrial invertebrates; however, the literature suggests that the by-products of wind farm development may, individually and in concert, have strong impacts on terrestrial invertebrates. Future research should address the degree to which wind farm developments affect terrestrial invertebrates, and possible research directions are suggested based on a literature review. Overall, despite the rapid development of wind farms, little is known about their interactions with invertebrates. Wind farms could be better sited and managed through informative studies addressing the points suggested in this chapter.

Introduction Invertebrates dominate the animal component of the terrestrial biosphere in terms of abundance, biomass and species diversity (Gaston 1991). They play critical roles as herbivores, predators, detritivores and pollinators, profoundly affecting local communities,

64  |  Wildlife and Wind Farms, Onshore: Potential Effects biomass turnover and ecosystem function (Collins & Thomas 1991). Terrestrial invertebrates, primarily insects, also form a critical and often dominant food resource for birds, bats, reptiles and small mammals, as well as other invertebrates (Pianka & Parker 1975; Drut et al. 1994; Valdez & Cryan 2013). Any effects of wind farm development on terrestrial invertebrates could therefore have impacts that reverberate throughout the broader community (Pace et al. 1999). Wind farms are rapidly developing in many areas of the world, and are generally located in windy areas (with wind speeds Figure 4.1  A number of wind farms in Scotland, >20  km/h) (Pimentel et al. 2002) with Wales and Northern Ireland have included monitoring for protected butterflies such as this Marsh available land, access roads, connection to Fritillary Euphydryas aurinia, even leading to haba transmission line and acceptable environ- itat plans to benefit particular species (e.g. RES mental conditions (Serrano González et al. UK & Ireland Ltd 2014). However, to date, such 2014). Turbines are rapidly being installed information has not been published in the peerin North America, Europe, China and Brazil reviewed literature. (Martin R. Perrow) to help meet rising energy demands. Most wind farms are sited in cultivated fields or in natural areas with short vegetation, such as prairie. An exception to this is the wind farms being built in Swedish boreal forests. Hilltops and mountains can be popular places for wind farms (Clarke 1989; Karydis 2013), in part because winds are often stronger and more reliable in these locations. Tropical localities, where invertebrates are most diverse, have seen little wind farm development. However, some invertebrates may have restricted distributions that overlap considerably with wind farms, potentially causing concern, as it is not yet known how wind farms may affect invertebrates. Furthermore, invertebrates can be locally abundant in the temperate zone where wind farm development is most common, and, given their diverse roles (i.e. as herbivores, pollinators, predators and detritivores), changes in these invertebrate communities could have pronounced top–down and bottom–up trophic effects within ecosystems.

Scope The aim of this chapter was to review the impacts of wind farm development on t­ errestrial invertebrates. The peer-reviewed literature was searched for studies investigating terrestrial invertebrates near wind farms (Web of Science search, last performed on 7 December 2015 with keywords wind farm* or wind turbine* and invertebrate* or insect*), but no published peer-reviewed studies were found that had measured invertebrate responses to wind farm development. Despite the growing literature on the effects of wind farms on birds and bats, very little is known about potential effects on invertebrates. Given this lack of research, this chapter instead outlines a host of potential impacts based on more general knowledge of ecological factors affecting invertebrate populations. This approach is not meant to be exhaustive but rather to help to establish a framework for future studies. The review is dominated by discussions of terrestrial insects because they are the most abundant and diverse of terrestrial invertebrates and so they have received the most

Terrestrial invertebrates  | 65

Figure 4.2  Schematic showing potential impacts of wind farm development on terrestrial invertebrates. Solid and dashed lines indicate direct and indirect impacts, respectively. (Creative Commons Share Alike, Blue73)

attention. In addition, data on other invertebrate groups such as crustaceans, arachnids and molluscs are comparatively rare. To organise the discussion, this chapter examines where wind farms are typically located and how invertebrates may overlap with these areas. The remainder of the chapter addresses wind farm impacts arising from two main sources: the turbines themselves with their spinning blades and associated environmental effects; and the associated effects from construction and use of roads, such as collisions and dust (Figure 4.2). These sources may affect invertebrates directly (e.g. from collisions with turbines or vehicles) or indirectly via habitat fragmentation and loss, chemical and noise pollution and dust, facilitation of the spread of invasive species and changes in local climate. Wind farms may also have neutral, positive or negative effects on invertebrate populations by altering higher trophic levels (e.g. Romero & Koricheva 2011). Potential impacts are summarised within this framework in the next section.

Themes Siting of wind farms Turbines have generally been placed in rows facing the prevailing wind direction, with neighbouring turbines separated by an appropriate minimum distance (Serrano González et al. 2014) (Figure 4.3A). Increasingly complex models are being used to micro-site turbines in patterns that generate more power and higher profits (Serrano González et al. 2014) (Figure 4.3B). These micro-siting decisions may strongly alter the impacts of wind farm developments on terrestrial invertebrates for a number of reasons. Because invertebrates are unlikely to be uniformly distributed across the landscape, the choice of turbine location may dramatically alter its biological impact, as variation in invertebrate density (due to, for example, patchy distribution of the resources on which they depend) may alter the probability of collision with turbine blades. At broader spatial scales, the arrangement of

66  |  Wildlife and Wind Farms, Onshore: Potential Effects

Figure 4.3  Micro-siting of turbines may strongly alter impacts on terrestrial invertebrates. (A) ­Turbines at older wind farms were usually arranged in rows facing the dominant wind direction; (B) complex models are used to micro-site turbines in newer wind farms to maximise profits. The spatial arrangement of turbines and associated access roads may alter the biological impacts of wind farms, including the impacts on invertebrates. (Google, USDA Farm Service Agency)

turbines will determine the construction of access roads, altering the degree and spatial pattern of disturbance and habitat fragmentation (Figure 4.3). Turbine placement may coincide with areas where insects accumulate, increasing insect mortality and potentially attracting insectivorous animals. Insects sometimes gather at hilltops and ridges (Alcock 1987), prime areas for both siting wind farms and micro-siting turbines. Furthermore, many insects migrate using wind currents (Johnson 1969) and migration routes may overlap with wind farms. For example, in the study of Zhang et al. (2007), moths migrated with prevailing winds, flying less than 500 m above ground at night during summer. Concentrations of migrating moths on or around turbines may attract insectivorous bats (Rydell et al. 2010). For example, about 40% of bats killed at wind farms in North America are Hoary Bat Lasiurus cinereus (Kunz et al. 2007; Arnett et al. 2008), which is a moth specialist (Black 1974). Most Hoary Bats killed at wind farms in New York and Texas had stomachs filled primarily with moths, but also with beetles, true bugs and crickets (Valdez & Cryan 2013). These findings suggest that bats feed on diverse and abundant insects in and around wind farms (Rydell et al. 2010). Given these considerations, information on invertebrate habitat relationships could aid micro-siting decisions, strongly altering any impacts of wind farm development on invertebrates.

Collisions Beyond coincidental overlap of wind farms with areas of high insect density, turbines may attract invertebrates. Many invertebrates, particularly insects, are attracted to heat (e.g. Thorsteinson 1958), because as ectotherms they rely in part on microhabitat selection to regulate body temperature (Angilletta 2009). The rotor hub of wind turbines is often

Terrestrial invertebrates  | 67 warmer than ambient temperature, potentially attracting insects to these warm moving parts. Insects may collide with blades or other moving parts when flying towards the source of heat. In the visible spectrum, many insects rely on excellent colour vision to navigate and find resources. For example, some colours are particularly effective at attracting pollinating insects, presumably because they resemble flowers (Abrahamczyk et al. 2010). Turbines are often painted white or light grey, colours that attract insects (Long et al. 2011). Finally, lights on and around wind turbines may attract insects and other invertebrates to these well-lit locations in an otherwise dark landscape (Nabli et al. 1999). Irrespective of whether insects are attracted to turbines or simply coincidentally occur in high abundance with turbines in some localities, substantial numbers of insects do collide with turbines in some localities. Some of the best evidence for extensive collision of insects with turbines comes from studies of the turbines themselves. Turbine operators had long noticed unexpected reductions in power produced by wind turbines with no change in wind speed. Operators could solve the problem by cleaning the turbine blades, which were coated in insect carcasses. The periodicity of cleaning blades appeared to vary widely among wind farms. When normally smooth turbine blades become rough with insect carcasses, flow separates from the blades, reducing the power generated by as much as one half (Corten & Veldkamp 2001). These changes in surface roughness of the leading edge of turbine blades driven by accumulation of insect carcasses are a prominent driver of blade performance and therefore energy production (Dalili et al. 2009). Although it is clear that large numbers of insects are killed on turbine blades, the effect of those losses on local insect populations has, to the authors’ knowledge, not yet been studied. Aside from collisions with the turbines, invertebrates may regularly collide with moving vehicles because maintenance of wind turbines requires heavy use of wind farm access roads (Ardente et al. 2008). Collisions with vehicles can be an important cause of mortality for insects both in flight and on the road surface, with measurable effects on local populations (reviewed by Muñoz et al. 2014). The most common insects killed on roads were Coleoptera (beetles), Diptera (true flies), Lepidoptera (butterflies and moths), Hymenoptera (bees, wasps and ants) and Odonata (dragonflies and damselflies) (Muñoz et al. 2014). A study of butterflies in the UK showed that 0.6–7% of local butterfly populations were killed by collisions with vehicles (Munguira & Thomas 1992). Mortality rates due to vehicle collisions typically increased with traffic volume and road size, but more studies are needed to determine whether differences in road surfaces (i.e. paved or gravel) and vehicle speeds affect insect mortality rates (Muñoz et al. 2014). Vehicles travelling at high speeds may create enough wind to catapult butterflies over the vehicle, thereby reducing collisions (McKenna et al. 2001). Some studies have found differences in mortality rates among form and between males and females of the same species. For example, in one study, smaller butterflies tended to have higher mortality rates along roads compared to larger species (Skórka et al. 2013). Furthermore, populations of invertebrate scavengers, such as beetles, may either increase near roads because roadkill augments food resources or be severely reduced because attraction to carcasses leads to the death of these scavengers. However, no studies were found that have investigated this question. Insects may perish after colliding with blades or owing to changes in pressure around the turbines. Similarly, insect carcasses may accumulate downwind of turbines and attract scavengers, including birds, small mammals and other insects. A pilot study in SE Wyoming, USA provides preliminary evidence for direct effects of wind turbines on insect populations (see Box 4.1).

68  |  Wildlife and Wind Farms, Onshore: Potential Effects

Box 4.1  Effects of wind turbines on abundance of terrestrial insects in southern Wyoming, USA In a pilot study, Dillon and Tronstad (2013) sampled insects at a 69-turbine wind farm in southern Wyoming, USA, during June 2012 (Figure 4.4A). Insects were collected upwind (two sampling stations), at the base and downwind (nine sampling stations) of a single turbine at 20  m intervals. Each sampling station (Figure 4.4B) included a vane trap (Figure 4.4C) (Stephen & Rao 2005) and three bee cups (pan traps) (Figure 4.4D), both of which primarily attracted pollinating insects such as bees, flies, butterflies, beetles and moths (Grundel et al. 2011). During 4,344  hours of sampling 1,313 insects were collected in vane traps and bee cups. The number of insects collected per sampling hour (vane traps and bee cups combined) was used as the metric of abundance because it standardised estimates across sites and dates for this study and facilitates future comparisons with other studies. Overall, 0.25 insects were captured per hour, but more insects were collected in vane traps (0.60 Figure 4.4  To determine the effect of wind insects per hour) than in bee cups (0.12 turbines on insect populations at a wind insects per hour). Vane traps collected farm in southern Wyoming (A), insects were collected at sampling stations spaced 20  m proportionally more beetles and butapart and placed upwind and downwind of a terflies than did bee cups, whereas bee turbine (B). Sampling stations included vane cups collected more flies than did vane traps (C) and pan traps (D) that primarily coltraps. Vane traps and bee cups collected lect pollinating insects. (Lusha Tronstad) similar numbers of bees and wasps. Overall, the methods were complementary in characterising the pollinating insect fauna. The mean abundance of insects was relatively constant along the sampling transect (ANOVA, F11,114=0.3770, P=0.96). However, more insects were captured on days with low wind velocities (50% of studies) negative effects.

19

14

Corvus corone

Eurasian Skylark

Passeriformes

Carrion Crow

Common Kestrel

2

Common Wood Pigeon

Falconiformes

15

Larus argentatus

European Herring Gull

Falco tinnunculus

2

Larus canus

Common Gull

Columba palumbus

3

Chroicocephalus ridibundus

Black-headed Gull

15

13

Numenius arquata

Eurasian Curlew

Columbiformes

Charadriiformes: Laridae

Charadriiformes: Scolopacidae

8 13

Northern Lapwing

Vanellus vanellus

4

13

European Golden Plover Pluvialis apricaria

Charadriiformes: Charadriidae

Haematopus ostralegus

Buteo buteo

Common Buzzard

Eurasian Oystercatcher

3

Milvus milvus

Red Kite

Charadriiformes: Haematopodidae

3

Circus cyaneus

Hen Harrier

Accipitriformes

Positive response

Scientific name

Taxonomic group Species common name

Table 7.1 – continued

126  |  Wildlife and Wind Farms, Onshore: Potential Effects

b

nb

b

nb

b

nb

nb

b

nb

b

nb

b

nb

b

nb

b

nb

Anseriformes

Anseriformes

Galliformes

Galliformes

Accipitriformes

Accipitriformes

Ardeiformes

Falconiformes

Falconiformes

Gruiformes

Gruiformes

Charadriiformes

Charadriiformes

Columbiformes

Columbiformes

Passeriformes

Passeriformes

104

284

6

5

68

45

1

2

18

5

6

29

35

5

18

16

12

Positive response

138

166

9

4

114

75

7

2

10

7

2

35

19

2

14

70

10

Negative response

57

37

60

44

63

63

88

50

36

58

25

55

35

29

44

81

45

Negative response (%)

All studies

0.03