Wetlands and natural resource

This conference brought together about900 participants from 61 countries, who discussed a very broad range of science-, and management-oriented issues related to wetland ecology and hydr

Ecological Studies, Vol 190 Analysis and Synthesis

Edited by

M.M Caldwell, Logan, USA

G Heldmaier, Marburg, Germany

R.B Jackson, Durham, USA

O.L Lange, Würzburg, Germany

H.A Mooney, Stanford, USA

E.-D Schulze, Jena, Germany

U Sommer, Kiel, Germany

Volumes published since 2002 are listed at the end of this book.

ISSN 0070-8356

ISBN-10 3-540-33186-7 Springer Berlin Heidelberg New York

ISBN-13 978-3-540-33186-5 Springer Berlin Heidelberg New York

This work is subject to copyright All rights are reserved, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilm or in any other way, and storage in data banks Duplication of this publication or parts thereof is permit- ted only under the provisions of the German Copyright Law of September 9, 1965, in its current version, and per- missions for use must always be obtained from Springer-Verlag Violations are liable for prosecution under the German Copyright Law.

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Editor: Dr Dieter Czeschlik, Heidelberg, Germany

Desk editor: Dr Andrea Schlitzberger, Heidelberg, Germany

Cover design: WMXDesign GmbH, Heidelberg, Germany

Typesetting and production: Friedmut Kröner, Heidelberg, Germany

31/3152 YK – 5 4 3 2 1 0 – Printed on acid free paper

Cover illustration: Large picture: Cladium jamaicense lawns with tree islands, Everglades

National Park, USA (Photo: J.T.A Verhoeven)

Small pictures: La Pérouse Bay, Manitoba (Photos Hudson Pay Projekt Team):Top The

effects of grubbing by lesser snow geese in early spring on the intertidal saltmarsh;

Middle Death of willow bushes and exposure of the surface organic layer after goose

grubbing in the supratidal marsh; Bottom Grazing exclosure indicating that in the

absence of grubbing the vegetation remains intact on the intertidal marsh

The two volumes on “Wetlands as a Natural Resource” in the book series EcologicalStudies (Volumes 190, 191) are based on the highlights of the 7thINTECOL InternationalWetland Conference in Utrecht, 25–30 July 2004 This conference brought together about

900 participants from 61 countries, who discussed a very broad range of science-, and management-oriented issues related to wetland ecology and hydrology, wetlandconservation and creation, the impact of global change and wetlands as a resource interms of food, flood protection and water quality enhancement The participants werefrom different sectors of society, i.e., science and technology (scientists 45 %; PhD stu-dents 20 %), natural resource management (20 %) and policy (15 %) There were 38 sym-posia with invited speakers centered around the nine conference themes We have giventhe organizers of these symposia the opportunity to produce one chapter for thesebooks with the integrated content of their symposium This has resulted in 25 chapters,

policy-of which 13 are included in Volume 190 under the heading “Wetlands and NaturalResource Management” and 12 in Volume 191 under the heading “Wetlands: Function-ing, Biodiversity Conservation and Restoration”

With these books, we had the aim to summarize the most important recent scientificresults in wetland science, their applications in wetland and water resource managementand their implications for the development of global, national and regional policies inthe perspective of the ever-progressing deterioration of natural wetlands and the majorimpacts that future climate change will have We hope that the integrated content of thechapters on such a wide scope of different fields in wetland science will serve as a valu-able source of information, both for professionals in environmental science and naturalresource management and for students and young professionals seeking to familiarizethemselves with these fields We also hope that the interaction between scientists fromdifferent disciplines, resource managers and policy makers will be stimulated by thecontent of these publications

We as editors have worked according to a strict time schedule and we want to thankthe authors for their timeliness in producing inspiring manuscripts and the scientistswho have contributed to the peer reviews of the chapters for their active and promptparticipation, which has enabled us to complete our task more or less according to thisschedule We acknowledge the series editor of the Ecological Studies book series, Prof

Dr Ulrich Sommer, for his invitation to produce these volumes as one of the outcomes ofthe INTECOL Conference We also thank Dr Andrea Schlitzberger of Springer for heradvice and help We would like to take the opportunity to thank all key people who madethe conference into such a success In particular we want to thank Prof Dr EugeneTurner and the other members of the INTECOL Wetlands Working group, as well as the

International and National Scientific Committees for their support We are mostindebted to the team that organized the conference, in particular the inner circle, FredKnol, René Kwant, Nienke Pot and Miranda Motshagen The members of the LandscapeEcology Group at Utrecht University are thanked for their enormous efforts during theconference.

These two volumes are the most tangible, durable result of the conference It is ourwish that they will find their way to wetland professionals and students worldwide andwill contribute to the wise use and conservation of the still large wetland resources thatremain on our planet

Utrecht, June 2006

Roland Bobbink, Boudewijn Beltman, Dennis F Whigham

These two volumes are major contributions from a well-run meeting inspired by the legiality and good will of the hosts This meeting sparked professionalism through theexpression of the finer parts of Dutch culture and, indeed, of all cultures The 7thInter-national Wetland Conference, like the preceding meetings, are successful because peoplecare about living systems – i.e., people, landscapes, science culture, political structures,birds, etc – as they go about trying to make things a little better and a little sooner thanwhen wetlands were first appreciated in their collective minds The successes from themeetings, exemplified by these two volumes, is partly because they enhance the possibil-ities for clarity and develop a strong scientific enterprise amidst the interactions of peo-ple in neutral spaces and a sometimes strong gradient of personalities and cultures Wenever quite know ahead of time what the results of the meetings will be, although it hasalways been wonderful to see them evolve to closure

col-It is humbling to know how small things influence others, which is a lesson in beingcareful, thoughtful and open These efforts and successes are an explicit recognition ofthe interdependency of our discipline interests, but also the fabric of human interactionsthrough politics, science, economics, etc This interdependency suggests that beinginvolved in wetland science and management is a great way to improve the quality of thenatural world, but also society The world needs, whether it knows it or not, the expertiseand clear thinking of experts of general and detailed understanding to contribute to thesocial good These two volumes do exactly that Kudos to the Editors!

R Eugene Turner, Chair

On behalf of the INTECOL Wetland Working Group

1 Wetland Functioning in a Changing World:

Implications for Natural Resources Management 1

J.T.A Verhoeven, B Beltman, D.F Whigham, R Bobbink 1.1 Introduction 1

1.2 Clarity on Wetlands and Water Use 2

1.3 Wetlands and Environmental Flows 4

1.4 Wetlands and Water Quality 5

1.5 Biogeochemical Insights 6

1.6 Wetlands and River Fisheries 8

1.7 Wetlands and Climate Change 9

1.8 Further Developments in Wetland Science and its Applications 12

References 12

Section I The Role of Wetlands for Integrated Water Resources Management: Putting Theory into Practice 2 Restoring Lateral Connections Between Rivers and Floodplains: Lessons from Rehabilitation Projects 15

H Coops, K Tockner, C Amoros, T Hein, G Quinn 2.1 Introduction 15

2.2 Threatened Life at the Aquatic–Terrestrial Interface 16

2.3 Reconnecting Side-Channels Along the Rhône (France) 18 2.4 Rehabilitation of Side-Channels of the River Danube (Austria) 21

2.5 ‘Environmental Flows’ for Rehabilitating Floodplain

Wetlands (Australia) 24

2.6 Lessons from Rehabilitation Projects 25

References 30

3 Sustainable Agriculture and Wetlands 33

F Rijsberman, S de Silva 3.1 Agriculture and Wetlands: Introduction 33

3.2 Water for Food, Water for Environment 35

3.2.1 “Ecosystems Produce the Water Used by Agriculture” 36

3.2.2 “Irrigated Agriculture Uses 70 % of the World’s Water” 39

3.2.3 “Water Scarcity: Fact or Fiction?” 41

3.3 Producing More Rice With Less Water 43

3.4 Towards a Dialogue Among Agronomists and Environmentalists 44

3.4.1 Water, Food and Environment Issues in Attapeu Province, Lao PDR 47

3.5 Research on Sustainable Agriculture and Wetlands 48

3.6 Conclusions: Towards Sustainable Agriculture and Wetlands? 49

References 50

4 Sustainable Water Management by Using Wetlands in Catchments with Intensive Land Use 53

C Yin, B Shan, Z Mao 4.1 Semi-Natural Wetlands Created by Humans Before the Industrial Age 53

4.2 Water Regulation by the Multipond Systems 55

4.2.1 Research Site Description 55

4.2.2 The Regulation Process for the Crop Water Supply by the Pond System 56

4.3 Other Ecological Functions of Ancient Semi-Natural Wetlands in a Modern Scientific Context 59

4.3.1 Sediment Retention Within the Watershed 60

4.3.2 Nutrient Retention and Recycling 61

4.3.3 Landscape Complexity and Biological Diversity 61

4.4 Wetlands and Human Activities in Harmony 62

4.5 Protection of Semi-Natural Wetlands Together with Natural Wetlands 63

References 64

Section II Wetland Science for Environmental Management

5 Constructed Wetlands for Wastewater Treatment 69

J Vymazal, M Greenway, K Tonderski, H Brix, Ü Mander 5.1 Introduction 69

5.2 Free Water Surface Constructed Wetlands 70

5.2.1 Free Water Surface Wetlands for Treatment of Wastewater and Non-Point Source Pollution in Sweden 72 5.2.2 The Role of Wetlands in Effluent Treatment and Potential Water Reuse in Subtropical and Arid Australia 75 5.3 Constructed Wetlands with Horizontal Sub-Surface Flow 79 5.4 Constructed Wetlands with Vertical Sub-Surface Flow 81

5.4.1 Danish Experience with Vertical Flow Constructed Wetlands 83 5.4.2 Constructed Wetlands with No Outflow 85

5.5 Hybrid Constructed Wetlands 86

5.6 Trace Gas Fluxes from Constructed Wetlands for Wastewater Treatment 89

5.7 Conclusion 91

References 91

6 Tools for Wetland Ecosystem Resource Management in East Africa: Focus on the Lake Victoria Papyrus Wetlands 97 S Loiselle, A Cózar, A van Dam, F Kansiime, P Kelderman, M Saunders, S Simonit 6.1 Introduction 97

6.2 Wetlands and Inorganic Carbon Retention 99

6.3 Wetlands and Nutrient Retention 102

6.4 Wetlands and Eutrophication 106

6.5 Ecological Modelling 110

6.6 Discussion 117

6.7 Conclusion 118

References 119

7 Predicting the Water Requirements of River Fisheries 123

R.L Welcomme, C Bene, C.A Brown, A Arthington, P Dugan, J.M King, V Sugunan 7.1 Introduction 123

7.2 The Hydrological Regime and Fisheries in Rivers 124

7.2.1 Fish Responses to River Flow 127

7.2.2 What River? 127

7.2.3 Linkages Between Hydrological Regime and Fish Catch 132

7.3 The Social and Economic Role of River Fisheries 135

7.4 Methods for Estimation of Environmental Flow Requirements 137

7.5 Guidelines for the Selection and/or Development of Tools for Determining Environmental Flows for Rivers and Wetlands 138 7.5.1 Legislation, Policy, and Practice Supporting Environmental Flows Should Focus on People 138

7.5.2 There is a Need to Understand the Ecosystem First, Before the Impacts on People can be Predicted 139

7.5.3 There is No Such Thing as a Single Flow with a Single Flow Condition 140

7.5.4 Tradeoffs are an Integral Part of Decision-Making and Scenario Generation is Vital 140

7.5.5 The River Ecosystem and Its Flow Regime Must be Compart-mentalized to Provide the Required Scenario Information 141 7.5.6 Present-Day Conditions Offer the Best Starting Point 143

7.5.7 Methods Should be Usable in Both Data-Rich and Data-Poor Situations 145

7.5.8 Uncertainty is a Reality – Adaptive Management is Crucial 145 7.5.9 Implementation is Central to Promoting and Improving Environmental Flows 146

7.6 Discussion and Conclusion 146

References 149

8 Water Management and Wise Use of Wetlands: Enhancing productivity 155

R.L Welcomme, R.E Brummet, P Denny, M.R Hasan, R.C Kaggwa, J Kipkemboi, N.S Mattson, V.V Sugunan, K.K Vass 8.1 Introduction 155

8.2 Trends in Capture Fisheries 157

8.2.1 Increasing Pressure – Decreasing Catch 157

8.2.2 Fisheries Management 158

8.3 Methods for the Enhancement of Inland Fisheries 158

8.3.1 Species Introductions 159

8.3.2 Stocking 159

8.3.3 Extensive Culture Methods 164

8.4 Social and Economic Implications 174

8.5 Discussion 175

References 176

Section III Wetland Biogeochemistry 9 Hydrological Processes, Nutrient Flows and Patterns of Fens and Bogs 183

W Bleuten, W Borren, P.H Glaser, T Tsuchihara, E.D Lapshina, M Mäkilä, D Siegel, H Joosten, M.J Wassen 9.1 Introduction 183

9.2 Appearance of Pristine Fens and Bogs 184

9.2.1 General 184

9.2.2 Climate and Mire Vegetation of the Western Siberian Taiga 185 9.3 Hydrology of Bogs: Examples from Canada, United States and Western Siberia 188

9.3.1 Aspects of Large-Scale Hydrology 188

9.3.2 Local Scale Hydrology of Bogs 189

9.3.3 Modeling a Western Siberian Bog 191

9.4 Fens: Analysis of a Large Pristine Fen in the River Ob Valley 194 9.4.1 General 194

9.4.2 Vegetation, Nutrients and Productivity 196

9.4.3 Hydrology and Modeling 196

9.4.4 Hydro-Ecological Integration 200

9.5 Discussion and Conclusion 201

References 202

10 Ecological Aspects of Microbes and Microbial Communities Inhabiting the Rhizosphere of Wetland Plants 205

P.L.E Bodelier, P Frenzel, H Drake, K Küsel, T Hurek, B Reinhold-Hurek, C Lovell, P Megonigal, B Sorrell 10.1 Introduction 205

10.2 The Microbial Habitat in the Wetland Rhizosphere 207

10.2.1 Root Structure and Function 208

10.2.2 Oxygen Distribution within Roots 208

10.2.3 Oxygen Concentrations and Fluxes in the Rhizosphere 210

10.3 Survival Strategies of Anaerobes in the Oxic Rhizosphere:

Acetogens as an Example 210

10.4 Functional Diversity and Activity of Free-Living N2-Fixing Bacteria 212

10.5 Microbial Community Stability in Response to Manipulation of the Vegetation 215

10.6 Wetland Roots as Hotspots of Microbial Iron-Cycling 220

10.6.1 Wetland Rhizosphere Ferrous Wheels: Introduction 220

10.6.2 Rhizosphere Fe(III) Reduction 221

10.6.3 Rhizosphere Fe(II) Oxidation 223

10.6.4 Rhizosphere Fe(II) Oxidation Scaled to Ecosystems 225

10.7 Methane-Processing Microbes in Wetland Rhizospheres 226 10.7.1 Italian (Vercelli) Rice Soil as a Model System 226

10.7.2 Microbes and Microbial Processes 226

10.7.3 The Controls 229

10.8 Summary and Prospects 229

References 231

11 Linkages Between Microbial Community Composition and Biogeochemical Processes Across Scales 239

A Ogram, S Bridgham, R Corstanje, H Drake, K Küsel, A Mills, S Newman, K Portier, R Wetzel (deceased) 11.1 Introduction 239

11.2 Microbial Controls on Decomposition 241

11.2.1 Decomposition of Plant Matter in Wetlands 241

11.2.2 Microbial Enzyme Activities as Indicators of Controls on Decomposition 243

11.3 Linking Decomposition with Microbial Community Composition 244

11.3.1 Anaerobic Carbon Cycle 244

11.3.2 Controls over CO2:CH4Ratios in Anaerobic Respiration in Wetlands 245

11.3.3 Sulfate and Iron Reduction as Important Routes for Mineralization in Fens 250

11.3.4 Linking Community Composition with Nutrient Status in Wetlands 252

11.3.5 Plant-Associated Microbial Communities Across Lanscapes 255 11.4 Linking Microbial Community Structure and Function with Environmental Parameters 259

11.4.1 Case Study: a Northern Everglades Marsh System 261

References 263

Section IV Wetlands and Climate Change Worldwide

12 Coastal Wetland Vulnerability to Relative Sea-Level Rise:

Wetland Elevation Trends and Process Controls 271

D.R Cahoon, P.F Hensel, T Spencer, D.J Reed, K.L McKee, N Saintilan 12.1 Introduction 271

12.2 Biotic Process Controls 273

12.2.1 Indirect Biotic Processes 274

12.2.2 Direct Biotic Processes 274

12.3 Hydrologic Process Controls 278

12.3.1 Surface Wetland Hydrology 279

12.3.2 Subsurface Wetland Hydrology 279

12.4 Findings from the SET Network 280

12.4.1 Data Analysis 280

12.4.2 The Salt Marsh SET Network 282

12.4.3 The Mangrove Forest SET Network 285

12.5 Further Considerations 287

References 289

13 Connecting Arctic and Temperate Wetlands and Agricultural Landscapes: The Dynamics of Goose Populations in Response to Global Change 293

R.L Jefferies, R.H Drent, J.P Bakker 13.1 Introduction 293

13.2 Links Between Modern Agriculture as a Food Source and the Increase in the Size of Arctic Goose Populations 296 13.3 Hunting Practices, Availability of Refuges, Agricultural Food Supplies and the Size of Goose Populations 297

13.3.1 Hunting Practices in Agricultural Landscapes and the Size of Goose Populations 298

13.3.2 The Synergistic Link Between Refuges and Agriculture: Effects on Wintering and Migrating Goose Populations 299

13.3.3 The Direct and Indirect Effects of Weather Patterns and Climate Change on Wintering and Migrating Goose Populations 300

13.4 Habitat Changes in Response to Population Growth of Geese 303 13.4.1 Effects of the Geese on Temperate Salt-Marsh Vegetation 303 13.4.2 Effects of Geese on Arctic Coastal Vegetation 306

13.5 Anthropogenic Constraints on Population Growth 309

13.6 Conclusion 311

References 312

14 Eurasian Mires of the Southern Taiga Belt: Modern Features and Response to Holocene Palaeoclimate 315

T Minayeva, W Bleuten, A Sirin, E.D Lapshina 14.1 Introduction 315

14.2 Peatlands of the Southern Taiga Belt of Northern Eurasia 316 14.2.1 The Features of the Southern Taiga Bioclimate 316

14.2.2 Peatland Distribution and Main Types 317

14.2.3 Main Features of Peatland Development 317

14.2.4 Main Features of Climate During the Holocene 319

14.2.5 Peat Accumulation Dynamics 321

14.3 Mire Development and Peat Accumulation Dynamics in the Key Areas During the Holocene 322

14.3.1 Study Sites in European Russia 322

14.3.2 Study Sites in Western Siberia 325

14.3.3 Study Methods 326

14.3.4 Holocene Peat Dynamics 327

14.3.5 Peat and Carbon Accumulation Rates 332

14.4 Discussion and Conclusions 334

References 338

Subject Index 343

Claude Amoros

Université Claude Bernard, Lyon I, 69622 Villeurbanne Cedex, France,e-mail: amoros@univ-lyon1.fr

Angela Arthington

Centre for Riverine Landscapes, Faculty of Environmental Sciences,

Griffith University, Brisbane, Australia

Jan P Bakker

Community and Conservation Ecology Group, Centre for Ecological andEvolutionary Studies, University of Groningen, PO Box 14, 9750 AA Haren,The Netherlands, e-mail: j.p.bakker@rug.nl

Boudewijn Beltman

Landscape Ecology, Institute of Environmental Biology, Utrecht University,

PO Box 80084, 3508 TB Utrecht, The Netherlands,

Department of Physical Geography, Utrecht University, PO Box 80115,

3508 TC Utrecht, The Netherlands, e-mail: w.bleuten@geo.uu.nl

Roland Bobbink

Landscape Ecology, Institute of Environmental Biology, Utrecht University,

PO Box 80084, 3508 TB Utrecht, The Netherlands,

e-mail: r.bobbink@bio.uu.nl

Paul L.E Bodelier

Centre for Limnology, Department of Microbial Ecology, Netherlands tute of Ecology (NIOO-KNAW), PO Box 1299, 3600 BG Maarssen,

Insti-The Netherlands, e-mail: p.bodelier@nioo.knaw.nl

Wiebe Borren

Centre for Limnology, Department of Microbial Wetland Ecology,

Netherlands Institute of Ecology (NIOO-KNAW) Rijkstraatweg 6,

3631 AC Nieuwersluis, The Netherlands, e-mail: w.borren@geo.uu.nl

Southern Waters Ecological Research and Consulting, Zoology Department,University of Cape Town, Private Bag Rondebosch, South Africa,

Dipartimento Scienze e Tecnologie Chimiche, University of Siena,

53100 Siena, Italy, e-mail: cozar@uca.es

Sanjini de Silva

International Water Management Institute, PO Box 2075, Colombo,

Sri Lanka, e-mail: sanjini.desilva@cgiar.org

Patrick Dugan

WorldFish Center – Cairo Office, 3 Abou El Feda Street, PO Box 1261, Maadi,Cairo, Egypt

Peter Frenzel

Max Planck Institut für terrestrische Mikrobiologie, Karl-von-Frisch-Straße,

35043 Marburg, Germany, e-mail: peter.frenzel@mpi-marburg.mpg.dePaul H Glaser

Department of Geology & Geophysics, University of Minnesota,

Minneapolis, MN 55455, USA, e-mail: glase001@umn.edu

University of Vienna, Institute of Ecology and Conservation Biology,

Althanstrasse 14, 1090 Vienna, Austria Present address: Institute of ology and Aquatic Ecosystem Management, Department of Water – Atmo-

Hydrobi-sphere – Environment, University of natural Resources and Applied LifeSciences, Vienna, Max Emanuel Strasse 17, A 1180 Vienna, Austria,

Institute of Environment & Natural Resources, Makerere University,

Kampala, Uganda, e-mail: fkansiime@muienr.mak.ac.ug

Limnology Research Group, Institute of Ecology, University of Jena,

07745 Jena, Germany, e-mail: kirsten.kuesel@uni-jena.de

Elena D Lapshina

Institute of Biology and Biophysics, Tomsk State University,

Prospekt Lenina 36, 634050 Tomsk, Russia, e-mail: edlapshina@hotmail.comSteven Loiselle

Dipartimento Scienze e Tecnologie Chimiche, University of Siena,

53100 Siena, Italy, e-mail: loiselle@unisi.it

Charles Lovell

Department of Biological Sciences, University of South Carolina, Columbia,

SC 29208, USA, e-mail: lovell@biol.sc.edu

US Geological Survey, National Wetlands Research Center, Lafayette,

Louisiana USA, e-mail: karen_mckee@usgs.gov

Patrick Megonigal

Smithsonian Environmental Research Center, PO Box 28,

Edgewater, MD 21037, USA, e-mail: megonigal@serc.si.edu

Aaron Mills

Kennedy Space Center, USA, e-mail: aaron.l.mills@nasa.gov

Department of Geology and Geophysics, University of New Orleans,

New Orleans, Louisiana, USA, e-mail: djreed@uno.edu

Barbara Reinhold-Hurek

Laboratory for General Microbiology, Faculty of Biology, University ofBremen, PO Box 33.04.40, Germany, e-mail: breinhold@uni-bremen.deFrank Rijsberman

International Water Management Institute, PO Box 2075, Colombo,

Sri Lanka, e-mail: f.rijsberman@cgiar.org

Neil Saintilan

Rivers and Wetland Unit, Science and Policy Division, Department of

Environment and Conservation, 59-61 Goulburn St, Sydney, PO Box A290Sydney South NSW 1232, Australia,

e-mail: neil.saintilan@environment.nsw.gov.au

Matt Saunders

Department of Botany, Trinity College, Dublin, Ireland,

e-mail: saunderm@tcd.ie

Brian Sorrell

National Institute of Water and Atmospheric Research, PO Box 8602,

Christchurch, New Zealand, e-mail: b.sorrell@niwa.cri.nz

Satoshi Ishida, Masayuki Imaizumi: 2-1-6 Kannondai, Tsukuba,

Ibaraki 305-8609, Japan, e-mail: takeo428@nkk.affrc.go.jp

Anne van Dam

UNESCO-IHE Institute for Water Education, Delft, The Netherlands,

e-mail: a.vandam@unesco-ihe.org

K.K Vass

National Research Centre on Coldwater Fisheries (ICAR), Bhimtal, Nanital,Uttranchal, India

Jos T.A Verhoeven

Landscape Ecology, Institute of Environmental Biology, Utrecht University,

PO Box 800.84, 3508 TB Utrecht, The Netherlands,

e-mail: j.t.a.verhoeven@bio.uu.nl

Jan Vymazal

ENKI, o.p.s.,Řícýanova 40, 169 00 Praha 6, Czech Republic and

Nicholas School of the Environment and Earth Sciences, Duke UniversityWetland Center, Box 90333, Durham, NC 27708, USA,

Smithsonian Environmental Research Center, PO Box 28, Edgewater,

MD 21037, USA, e-mail: whighamd@si.edu

Chengqing Yin

Research Center for Eco-Environmental Science, CAS, Beijing 100085,P.R China, e-mail: cqyin@mail.rcees.ac.cn

Ecological Studies, Vol 190 J.T.A.Verhoeven, B Beltman, R Bobbink, and D.F.Whigham (Eds.)

Wetlands and Natural Resource Management

© Springer-Verlag Berlin Heidelberg 2006

Implications for Natural Resources Management

Jos T.A Verhoeven, Boudewijn Beltman, Dennis F Whigham,Roland Bobbink

1.1 Introduction

Wetland ecosystems are a natural resource of global significance Historically,their high level of plant and animal (especially bird) diversity is perhaps themajor reason why wetland protection has become a high priority worldwide,supported by international agreements, such as the Ramsar Convention andthe International Convention of Biological Diversity (Fig 1.1) More recently,

a number of goods and services provided specifically by wetland ecosystemshave been identified that may even outweigh biodiversity in terms of theirimportance for human welfare and sustainable natural resource managementworldwide Wetlands, as transitional zones between land and water, provide anatural protection against extreme floods and storm surges They may alsostore freshwater to be used for drinking-water preparation or for irrigation.Wetlands bordering streams, rivers and lakes have a water quality enhance-ment function that is increasingly recognized As natural habitats for fish,riverine wetlands, shallow lakes and coastal wetlands have the potential toproduce large fish stocks, which are exploited commercially in some regionsbut could be enhanced by restoring wetlands in degraded areas Because wet-lands often provide spawning habitats, their importance as a source of juve-nile fish for large aquatic lakes and river channels should not be underesti-mated In addition to these local and regional benefits, wetlands as a globalresource provide a net sink of carbon dioxide The world’s peatlands are theonly type of terrestrial ecosystem with a long-term net carbon storage func-tion However, the large amounts of carbon that have accumulated historically

in peatlands may be released as a result of drainage or excavation

Wetlands do produce a striking variety of goods and services and it is nowonder that, more often than any other terrestrial ecosystem, they are used by

environmental economists to illustrate ecosystem functions and their value tomankind However, in spite of the high biodiversity and the high importance

of the goods and services of wetland ecosystems, their global status is poor.Many wetlands, particularly river floodplains, deltas and estuaries, have beenstrongly degraded because of human impacts Early civilizations were partic-ularly successful in these areas, where agriculture thrived because of the nat-ural fertility of the soils and transport was favoured by the river channels Inthe industrial era, these impacts became dramatically negative as a result offloodplain reclamation, poldering, construction of flood control structures,drainage for agriculture, excavation of peat for fuel and modification andstraightening of river channels in favour of navigation Worldwide, more than

50 % of the wetland resource has been lost because of these reasons In somedensely populated regions in Europe, North America and East Asia, more than

80 % of the wetlands have been lost or severely degraded

This volume, containing an integrated account of a number of major posia presented at the 7th INTECOL International Wetlands Conference inUtrecht, investigates the major natural resource management issues involved

sym-in the protection of the remasym-insym-ing wetland resource, the enhancement of thegoods and services arising from this resource and the restoration of degradedwetlands and wetland functions In this introductory chapter, we will give anoverview of recent advances in the comprehension of how both wetland bio-diversity and the wetland ecosystem goods and services can be enhanced bymanagement decisions, as treated in more detail in the other chapters of thisvolume We will also identify remaining gaps in scientific knowledge andunderstanding that need to be addressed to optimize the decision-makingprocess on wetland land use and management

1.2 Clarity on Wetlands and Water Use

It is widely recognized that the limited availability of clean freshwater willincreasingly become a matter of controversy between local communities inmany semi-arid regions of the world Access to healthy freshwater resourceshas even been identified as a fundamental human right The relation betweenwetlands and the availability of freshwater recently led to confusion amongnatural resource managers As Rijsberman and De Silva point out in Chapter

3, one of the services of wetland ecosystems was described as the ‘providing’

or ‘provision’ of water This service would suggest that wetlands are sources ofwater and do not compete with other water-demanding sectors such as agri-culture or water use for sanitation or industry In this view, wetlands wouldeven be potential sources of water However, in reality, wetlands are as muchdependent on water as these other sectors Being systems with a high watertable, they can only maintain their characteristic biota and functioning if

brackish pools on the

island of Texel, The

Netherlands

Fig 1.2 Cladium

jamaicense (sawgrass)

lawns with tree islands

in Shark Slough,

Ever-glades National Park

Fig 1.3 A stand of

Nelumbo nucifera

(water lotus) in

Kakadu National Park,

Australia The water

lotus is a typical

wet-land plant with

aerenchyma

water outputs are balanced by water inputs, in a way typical for the waterregime of the wetland in question Most wetland types require inputs of sur-face water or groundwater in addition to the inflow through precipitation Inpractice, wetlands often compete for water with agriculture or drinking-waterpreparation, in particular in semi-arid regions.

A first example is the use of water in many (sub)tropical countries forirrigation, which has led to the drying-out of vast wetland resources Waterresource managers often are mainly involved with the so-called ‘blue’ waterresources, mainly to be used for urban and industrial use The water used forirrigation, mostly present as soil moisture, also leads to a major regionalwater loss which is equal to the amount of water evapotranspired by thecrops This so-called ‘green’ water use is now increasingly being addressed in

an integrated way with other water uses by water resource managers Thenotion that wetlands ‘provide’ water has been nuanced: water conservationmay be optimized by using wetlands as reservoirs where water can be tem-porarily stored

A second example of a controversy on the uses of limited water resources

is the situation in the Everglades, Florida Here, a large freshwater surfaceresource flowing over the land surface south of Lake Okeechobee is usedincreasingly for urban, agricultural and industrial purposes by the metropol-itan region surrounding Miami As a result, the large wilderness area of theEverglades wetlands (see Fig 1.2), partly protected in nature reserves (e.g.Everglades National Park), is suffering from water shortage and is threatened

on the longer term A multi-million dollar Comprehensive EvergladesRestoration Plan (CERP; http://www.evergladesplan.org/index.cfm) has beendesigned to mitigate water shortages in the future It remains to be seenwhether this will provide a sustainable solution to the protection of the Ever-glades and its many biota and other values

1.3 Wetlands and Environmental Flows

The definition and implementation of ‘environmental flows’ have become amajor management tools in river catchments worldwide, particularly in semi-arid regions The idea is that so much water in river systems is diverted andused for agriculture, cities or industry that rivers can no longer function nat-urally River flow and flood events are increasingly limited to a narrow zonebordering the river channel, while the lateral interactions with the oftenextensive floodplains become diminished This has drastic negative conse-quences for the biota characteristic for floodplains and for the goods and ser-vices provided by the floodplain habitat Environmental flows (EFs) aredefined as a minimum river discharge needed to meet certain targets in terms

of biodiversity and/or ecosystem goods and services Restoration of lateral

connectivity by bringing floodwater only to selected parts of the originalfloodplain may help in restoring the intensity and temporal dynamics of typ-ical flooding events, rather than allowing the water to create too small a flood-ing event in the total floodplain This is illustrated for rivers in Australia byCoops et al (Chapter 2) and for tropical rivers by Welcomme et al (Chapter7) The EF concept is in the stage of becoming widely accepted among waterresource managers as a tool to maximize the quality of biodiversity restora-tion and associated fisheries in large river floodplains with diminished riverdischarge Hopeful developments have been initiated in several large Euro-pean river catchments, where river rehabilitation projects have focused on: (1)the restoration of lateral connections by removing so-called ‘summer dikes’,which has resulted in a higher frequency of flooding of floodplain habitats,(2) the restoration of side-channels and river dunes and (3) the enhancement

of river water quality Some of the projects described in Chapter 2 illustratethe successful restoration of floodplain habitats in the basins of the riversRhine, Rhone and Danube

1.4 Wetlands and Water Quality

The role of wetlands in river and lake catchments in enhancing water quality

is well established.A recent review gives a global perspective of this ecosystemservice in areas of the world with high intensity of agricultural use (Verho-even et al 2006) Riparian wetlands bordering lower-order streams and flood-plains of mid-size and larger rivers have a great potential to remove nutrientsand pollutants from through-flowing water Nitrate in surface and subsurfacerunoff from agricultural fields and pastures, when exposed to superficial soillayers in the riparian zone, is transferred to gaseous nitrogen species andemitted to the atmosphere, while phosphate and ammonium are retained invegetation or bacterial biomass, adsorbed to soil particles or laid down in sed-iments Long-term loading of these zones, however, enriches these riparianwetlands, which often leads to the loss of characteristic species Critical load-ing rates for N and P have been established for freshwater wetlands, beyondwhich losses of plant and animal species are to be expected Riparian zoneshave also been shown to be only effective at the catchment scale if they aresufficiently large and continuous in the landscape Only when their total areacomes near 5 % of the total catchment area can they really make a difference

to water quality in the catchment Wetlands restoration schemes in tural areas should take into account these limitations

agricul-The chapter by Yin et al (Chapter 4) deals with a rural system for waterresources management which has been developed in the southern part ofChina This so-called ‘multipond’ system, a system of many shallow ponds inthe landscape connected by ditches, is the result of 2000 years of engineer-

ing experience and combines benefits such as water storage, flood protectionand water quality enhancement Another example of the pivotal role of nat-ural wetlands in this respect is given by Loiselle et al (Chapter 6) for theextensive papyrus wetlands around Lake Victoria in Africa These wetlandsare enormously important to halt the eutrophication of the large lake Manylocal communities around the lake depend on the fisheries as their mainsource of protein In addition to the nutrient removal service, these wetlandsprovide a number of other important goods and services, such as papyrusstems, protection from damage by storm surges and a habitat for juvenilefish.

Another application of the water quality enhancement service of wetlandecosystems is the construction of wetlands just for this purpose Vymazal et

al (Chapter 5) give a thorough review of the latest knowledge on the mance, efficacy and application of different kinds of constructed wetlands.The past 40 years of experience with these systems has taught us that the bio-geochemical processes in wetlands can be used most optimally by designingand managing them in a ‘tailor-made’ way, according to the nature and con-centration of the pollutants, the amount of discharge to be treated and the cli-matic conditions Designs that combine different types of constructed wet-lands in sequence (‘hybrid systems’) have been shown to be most effective Anexample of such a system is a combination of a vertical-flow wetland, in whichorganic matter is broken down and nitrification can take place, followed by ahorizontal-flow wetland in which denitrification reduces the N content of thewater In almost all cases, constructed wetlands form an inexpensive and sus-tainable alternative to more technological solutions which require higherenergy inputs and more expensive investments

perfor-A disadvantage of constructed wetlands is that they emit relatively highquantities of the greenhouse gases nitrous oxide and methane This is partic-ularly true for highly nutrient-loaded wetlands, which mostly have only a lim-ited surface Better understanding of the factors controlling emission rates ofthese gases may give additional guidelines for the management of these sys-tems

1.5 Biogeochemical Insights

The biogeochemical functioning of wetlands is a very challenging and plex research subject The high water table near the soil surface and the tem-poral patterns of water level fluctuations create many redox gradients in spaceand time, which leads to complex interactions among plants, microbes andgeochemical processes Redox cycles are often driven by the activity of aero-bic and anaerobic bacteria and by the availability of alternative electronacceptors such as nitrate, iron, manganese, sulphate and carbon dioxide The

com-role of the plants is that they produce organic substances in the rhizospherethrough leakage of dissolved substances and death of plant parts, summa-rized as ‘rhizodeposition’ Further, wetland plants have aerenchyma, a system

of air-filled cavities bringing oxygen to the roots and rhizomes (Fig 1.3) gen leaks into the rhizosphere to a certain degree

Oxy-Recent studies have focused on the role of bacteria in wetland pheres Bodelier et al (Chapter 10) give a fascinating overview of recentresults in this field New molecular methodologies such as micro-array tech-nology have enabled estimations of the diversity of various functional groups

rhizos-of bacteria Large differences in diversity were found Diazotrophic microbes,which are capable of fixing atmospheric nitrogen, show a remarkable highdiversity in wetland rhizosphere systems This high degree of functionalredundancy ensures the sustaining of N2fixation under a wide range of differ-ent environmental conditions This indicates the great importance of this eco-logical function for the ecosystem Microbes active in the cycling of iron inwetland soils have been found to show a rather poor diversity Results of newstudies of these bacteria has revealed that the redox cycles involving iron inwetland soils are primarily mediated by microbes and not by physicochemi-cal processes, as previously generally assumed Much progress has also beenmade in the study of methanogenic and methane-consuming bacteria in wet-lands The balance between methanogenesis and methane oxidation deter-mines the emission of methane, an important greenhouse gas Knowledge onthe ecophysiology and identity of the groups of bacteria involved in the twoprocesses is urgently needed to understand the conditions favouring methaneemission and to develop management approaches to minimize such emis-sions from wetlands

A major bottleneck for linking this new information of the functional ogy of microbial taxa to the fluxes of matter and energy at the ecosystem level

ecol-is the enormous difference in the scales in space and time at which themicrobes operate, in comparison to the vegetation or the environmentaldynamics such as flooding or sedimentation New integrative approachescombining the expertise of microbiologists, geochemists, landscape ecolo-gists and statisticians is needed for such linkages Ogram et al (Chapter 11)explain some of these approaches and apply a combination of a clusteringmethod, stepwise discrimination and canonical discrimination to a large dataset of biogeochemical studies made in the Northern Everglades They wereable to link microbial activity data (e.g alkaline phosphatase activity) to gra-dients in total phosphorus richness; and they concluded in a more generalway that microbial activities are demonstrably responsive to environmentalvariables Together with the new methodologies in microbial ecology, thesenew approaches at the landscape-scale to investigate the implications ofmicrobial activity at the system and landscape level, form a very promisingnew field in wetland ecology that needs further exploration by interdiscipli-nary teams

The vast peatland areas in the northern hemisphere are to a large degreedegraded because of human-induced drainage and/or peat cutting in themore densely populated, more southern areas of the peatland regions Verylarge areas remain in a more or less pristine state in the remote, more north-ern areas in Siberia and Canada Detailed study of the functioning of theselarge, pristine peatlands has lagged behind that of the degraded systemsbecause they are so remote, inaccessible and large-scale Bleuten et al (Chap-ter 9) describe the ecohydrological functioning of large peatland complexes inSiberia and Canada and show that bog–fen gradients in these very extensiveareas do not always follow standard patterns, because the hydrology in the toplayer of the peatlands is so dominated by horizontal, rather superficialthroughflow, transporting rain-water or groundwater over quite large dis-tances These hydrological processes have been modelled, revealing a betterunderstanding of these vast wetlands which are so important globally because

of their carbon storage function

1.6 Wetlands and River Fisheries

One of the major goods produced by wetlands which are unambiguously ued by humans is fish Freshwater wetlands associated with river or lake sys-tems are a major spawning and feeding habitat for a whole range of fishspecies which are, often commercially, exploited by local fisheries The sameholds for brackish and saltwater wetlands which have a function as breedinggrounds for juvenile fish later dispersing toward coastal seas or the oceans.River fisheries have decreased in importance in regions of the world wherethe large river catchments have been used for intensive agriculture and indus-try and the river channels have been diked and dammed for navigation andthe production of electricity.While rivers in many temperate regions have losttheir integrity, more naturally functioning rivers do still occur in north-tem-perate, boreal and (sub)tropical regions Particularly in developing countries,the extra protein source provided by river fisheries is very important to sup-port rural economies and their welfare Welcomme et al (Chapter 7) indicatethe threats to river fisheries in tropical regions because of the gradual damage

val-to the natural functioning of rivers because of human disturbances Thediversion of river water for irrigation, changes of the river channel for naviga-tion and the building of dams become more and more prominent They alsopoint to the concept of EFs to help solve questions associated with unexpectednegative effects of changes to river functioning for river fisheries Based onthe current understanding of the relation between river hydrology and theoccurrence and productivity of major fish species, EFs can be determinedwhich are required to maintain a certain level of fish production This infor-mation on EFs can be used in the decision-making process to weigh the ben-

efits of irrigated agriculture versus river fisheries The authors describemethodologies to assess the types of EF necessary in a particular case andgive examples where this approach has worked well in countries in southernAfrica (Mozambique, Tanzania, Zambia) The chapter clearly shows howimportant water issues are in wetland resources management.

Apart from improving the hydrology, there are other ways to enhance thesuccess of river fisheries in developing countries In Chapter 8, Welcomme et

al give an overview of approaches to improve fish catches based on tional experience of rural communities Such methods include measures tooptimize the landscape for fish catch, e.g the construction of ‘drain-in ponds’,parallel depressions in floodplains to keep fish in the floodplain as the floodsrecede Fish stocking in combination with the use of fertilizer is another wellknown method to enhance fish production The chapter gives detailed exam-ples of stocking procedures and investigates their opportunities and limita-tions Often, stocking is a very successful method to increase fish catch, butcaution should be used with respect to the use of non-native species and thelevel of fertilization Species introductions have led to large-scale invasions,with negative consequences for the native fish populations Eutrophication isthe risk associated with too high a level of fertilization A number of in-sitemeasures are also discussed, e.g.‘brush parks’, like the use of aquatic plants orreed screens to provide spawning habitat and shelter, or the use of water levelcontrol structures to manipulate water levels to facilitate both fish growth andfish catch The wise use of such measures strongly contributes to riverine fishcatch Communication of this knowledge to wetland users around the world isvery important

tradi-1.7 Wetlands and Climate Change

All terrestrial ecosystems are anticipated to react strongly to the predicted mate change that will take place in the next century as a result of the enhancedgreenhouse effect Projected changes in climate mainly encompass anincrease in average global temperatures and very distinct changes in rainfallpatterns, with more extreme episodes of heavy rainfall and/or severe drought.Further, the mean sea level is expected to rise at least 30 cm, with some esti-mates predicting even 80 cm The impacts of these climatic changes areexpected to be exceptionally large for the world’s wetland ecosystems Thebalance between water inputs and outputs, which determines the waterregime and ecological characteristics of all wetland ecosystems, will change,with enormous consequences, such as changes in the flooding frequency,amplitude and duration of large river–floodplain systems, paludification oflow-lying areas, saltwater intrusion into coastal habitats, more complete andlonger desiccation of wetlands and shrinking of peatlands

cli-Clues for understanding the impact of climatic changes on the rate of peataccrual in bogs and fens can be derived from stratigraphic research in peat-lands A study of Russian mires within the southern taiga belt in the northernhemisphere by Minayeva et al (Chapter 13) clearly demonstrates substantialchanges in peat growth and carbon accumulation in response to variations inpalaeoclimatic conditions Bog sites that had little or no contact with ground-water were more sensitive to palaeoclimate fluctuations than groundwater-fed mires.

Peat accumulation rates at the Malaya–Icha rain-fed bog site in WestSiberia varied especially during the early Holocene as a result of changes inthe sequestration rate, which can be attributed to climate changes Within theHolocene, there was a steady growth of peatland area in this region, resulting

in an expansion of peat deposits and increased carbon storage ManyEurasian mires tended to grow faster in cold periods and to slow down inwarmer periods during the past three millennia Even if the vegetation of spe-cific mire did not react to minor climatic changes (according to data frommacrofossil analysis), such changes were reflected in the rates of carbon accu-mulation A future climate change resulting in a temperature rise (IPCC 2001)can enhance primary production and decomposition in mires, with a net neg-ative effect on carbon sequestration, particularly when the climate becomesdrier However, if precipitation increases more than evapotranspiration com-bined with higher temperatures, a rapid peat growth and higher carbonsequestration may occur locally

Coastal wetlands such as saltmarshes and mangroves are, more than anyother wetland type, sensitive to changes in mean sea level Through the inter-action of biotic and abiotic processes, their elevation often graduallyincreases and can keep up with sea level rise Plant growth and associatedorganic matter accumulation, sedimentation, algal mat formation and animalburrowing all contribute to slowly increasing ground levels and a lateralexpansion in coastal wetlands It is clear that increased rates of global sea levelrise as a result of climate change can be expected to have drastic impacts onthe extent and functioning of these wetlands However, quantitative relation-ships between sedimentation and erosion and the role of plants and animals

in coastal wetlands, as influenced by sea level rise, are still almost unknown.Cahoon et al (Chapter 12) report on the SET-MH methodology as an example

to investigate these relationships SET stands for surface elevation tables,

per-manently installed measuring devices for assessing marsh elevation, whereas

MH means marker horizons, layers of dyed clay which can be buried at a

known depth to measure sediment accretion or erosion

Currently, there is an informal SET-MH network of scientists in differentparts of the world who have installed these devices in coastal wetlands andexchange information on their results In some areas of the United States andEurope, there are already more than 15 years of data available It has becomeclear that many coastal wetlands do increase their elevation at the same pace

as the current sea level rise Large differences in rates of surface accretionhave been found in relation to sediment inputs, erosion phenomena, macro-phyte productivity and algal growth These data are being used in modelsdescribing soil accretion in relation to environmental factors The models are

of great value for predictions of the effects of future enhanced sea level risescenarios associated with climate change First results of such analyses indi-cate large losses of coastal wetland area as a result of increased sea level rise.More research is needed to evaluate the more indirect effects of climatechange on marsh accretion, e.g through modified river discharge andgroundwater flow, changes in plant growth, shifts in the latitudinal distribu-tion of plant communities and the way these interact with the effects of sealevel rise

Another way to evaluate the consequences of climate change on wetlandecosystems is to investigate the response of key species or functional groups.The chapter by Jefferies et al (Chapter 13) gives an overview of the responses

of goose species to changes in agricultural land use and climate in the ern hemisphere It is clear that these changes have strongly influenced thepopulation numbers and migration behaviour of goose species frequentingwetlands and, increasingly, also crop fields and pastures The Arctic-breedinggoose species (i.e barnacle goose and Brent goose) breed in northern tundraregions and traditionally used to winter-feed in wetlands, such as saltmarshesand seagrass beds In the past 50 years, they have increasingly started to feed

north-on agricultural croplands and pastures while wintering As agriculture hasbecome much more intensive, with higher crop production and higher foodquality, the population numbers of most goose species have increasedstrongly This has become quite apparent in the numbers of wintering geese inwarm/temperate regions on both sides of the Atlantic Apart from this land-use-driven change, global climate change will also influence the populationdynamics of goose species During the spring migration from their winteringgrounds to the breeding areas, the Arctic-breeding species, at least in Europe,need to stage at grassland or wetland sites for extra foraging during the longmigration flight They move northward just in time to reach staging siteswhere the air temperature is between 3 °C and 6 °C, the temperature at whichthe onset of the spring growth of grasses occurs In the event of increasedglobal warming, it might be expected that the northerly spring migration willoccur earlier However, the presence of the boreal forest with its near absence

of grass and croplands limits the ready accessibility of forage plants thatrespond to warmer temperatures early in the season There are already indi-cations in the migration behaviour of Brent goose and lesser snow goose thatthe subtle interplay between the direct and indirect effects of climate on plantgrowth and the foraging responses of geese can result in winter-range exten-sions and changes in the migration routes of birds It is hard to predictwhether these changes will lead to the selection of new staging sites and/ornew breeding grounds at different locations, which may have further drastic

impacts on population sizes As geese, through their grazing activity, oftenhave a major impact on the vegetation of the wetlands where they feed, thesechanges may drastically impact the wetland ecosystem functioning as well.

1.8 Further Developments in Wetland Science

and its Applications

The importance of ecosystem services provided by wetlands justifies a highpriority for scientific studies of wetland ecosystem functioning Water qualityimprovement, enhancement of freshwater fish production, sustainable use ofwater for irrigation and river management for flood protection are naturalresource management issues increasingly recognized by regional andnational authorities The scientific evidence for these ecosystem services isgrowing The most important further scientific priorities remain: (1) theunderstanding of how these services can be optimized in a sustainable way,simultaneously ensuring the conservation and restoration of natural habitatfor plants and animals and (2) the anticipation of changes that will be pro-voked by future climate change, by using scientific information on ecosystemfunctioning in predictive models It will be a challenge to try to work with thechanges in climate and associated regional water regimes to further approachthe above-mentioned targets of sustainable wetland and water resource man-agement

The Role of Wetlands for Integrated Water Resources Management: Putting Theory into Practice

Floodplains: Lessons from Rehabilitation Projects

Hugo Coops, Klement Tockner, Claude Amoros, Thomas Hein,Gerry Quinn

2.1 Introduction

Most large rivers have been strongly modified by human activities, includingflow regulation and floodplain embankment Out of the largest river systems

in the northern hemisphere, at least 77 % can be considered to be moderately

to strongly affected by dams (Dynesius and Nilsson 1994), having severeimpacts on natural stream flow and floodplain hydrology Additionally, inputs

of pollutants are very high, mainly because river corridors are traditionallythe places where urban and industrial development and agricultural produc-tion occur The negative effects include loss of biodiversity, reduced biogeo-chemical processing and declining water provision for human use, recreationand ecosystems For various large rivers in Europe and North America, reha-bilitation plans have been formulated and initiated to achieve partial recoveryfrom past degradation (Buijse et al 2005) However, such initiatives often havestarted in isolation and without the full use of experiences gained in com-pleted rehabilitation projects

Despite growing information on their ecological functioning, manyaspects of river–floodplain ecosystems are rather poorly understood Limitedunderstanding prohibits accurate forecasts of consequences of ecosystemmanipulations and the attainability of restoration targets – even when a com-plete description of their patterns and processes has been made Ecosystemresponses to environmental modifications are usually not linear but stochas-tic and delayed, governed by catchment climate and hydrology, spatially andtemporally interacting, and operating differently on ecological functions atwidely varying scales The complex spatio-temporal dynamics of floodplainecosystems are reflected in their patterns of biodiversity (Ward et al 1999).Intermittent flooding plays a key role in maintaining different successionalstages within a variety of lentic, lotic and semi-aquatic habitat types In these

Ecological Studies, Vol 190 J.T.A.Verhoeven, B Beltman, R Bobbink, and D.F.Whigham (Eds.)

Wetlands and Natural Resource Management

© Springer-Verlag Berlin Heidelberg 2006

dynamic environments, many biota depend on boundaries (transition zonesbetween habitat patches) and different degrees of connectivity (interactionsbetween habitat patches).

Until recently, the main river channel has been the key focus of riverresearch Lateral (semi-)aquatic habitats – ponds, backwaters, and tributaryconfluences – have been widely ignored or studied in isolation A reason forthe underestimation and undervaluation of lateral water bodies in riverresearch is their almost complete absence in small headwater streams (wheremost river research has been carried out) and in heavily modified down-stream sections Lateral aquatic habitats are among the first landscape ele-ments that disappear as a consequence of river regulation and flow control(comparable to vegetated islands and gravel bars) However, the understand-ing of the functional and structural role of these habitats along river corridorsforms a prerequisite for successful and sustainable river management (Karaus2005)

In this chapter, we present several case studies that highlight the tion potential of interactions between the river and its floodplain and addresstheir value for conservation and management of large rivers First, we addressthe aquatic–terrestrial interface dynamics and the resulting biodiversity oflateral habitats within river corridors, as illustrated by riparian arthropods.Then, two local restoration cases are presented in more detail, in whichriver–floodplain connectivity was restored, aiming at enhancing species rich-ness and nutrient processing, respectively We also explore the concept of

restora-‘environmental flows’ in semi-arid regions, an increasingly important tool forrestoring ecological function and biodiversity of floodplain wetlands on largeregulated rivers We finish by pointing out what lessons should be drawn fromthese case studies, to the benefit of planning and design of new restorationprojects and, eventually, for upscaling measures to the scale of river sections

or entire river systems

2.2 Threatened Life at the Aquatic–Terrestrial Interface

Only recently have ecologists begun to better understand the flow of matterand organisms across habitat boundaries, which is particularly tight inriver–floodplain ecosystems (Polis et al 2004) Floodplains are pulsed sys-tems; therefore, organisms should be able to cope with large changes in theavailability of resources In particular, communities living at the aquatic–ter-restrial interface are subject to pulsed resources, such as stranded organicmatter and pulses of emerging aquatic insects Recent investigations of theaggregative response of arthropods to short-term resource pulses demon-strated the different availability of riparian arthropods to react to changes inresource availability Their response clearly depends on their general feeding

strategy (Paetzold 2005).Alterations of the flow regime, channel modification,and removal of buffer strips can alter the riparian community indirectly byimpeding the energy flow across the boundary (Paetzold and Tockner 2005).Terrestrial shoreline communities consist of an abundant and oftenendangered arthropod community that is very susceptible to human impacts.Riparian arthropods can be used as sensitive indicators to assess the ecologi-cal integrity of river corridors, as already successfully applied in theRhône–Thur river restoration project in Switzerland (A Peter, personal com-munication) The great advantage of shoreline communities as indicators isthat they can be applied in small streams and large rivers and they provideinformation not only on local habitat conditions but also on the functionallinkage between water and land, a key advantage to the more traditional indi-cators (e.g benthic invertebrate community structure).

In a recent study, Karaus (2005) quantified the species diversity of benthicinvertebrates along three Alpine river corridors (Swiss Rhone, Thur, Taglia-mento) by including the lateral dimension along each corridor Between 14and 17 1-km reaches along each corridor and four aquatic habitat types(when present) within each reach were sampled Results clearly demonstratedthat lateral habitats disproportionately contributed to longitudinal diversity(Fig 2.1) Overall, 162 taxa of Ephemeroptera, Plecoptera, and Trichopterawere identified in 119 composite samples, which was between 73 % and 77 %

of the total expected richness along each corridor Lateral habitats

Fig 2.1 Cumulative (%) and total species richness of Ephemeroptera, Plecoptera, and

Trichoptera along three Alpine river corridors For backwaters, ponds, and tributaryconfluences, only those taxa that did not occur in previous habitat types were added.Jack-knife analyses were used to calculate total expected taxon richness for each individ-ual river corridor (source: U Karaus and K Tockner, unpublished data)

tributed >50 % to total corridor species richness, although they covered

<10 % of the aquatic surface area (Karaus 2005) Further, diversity was chically partitioned into its components (alpha, beta, gamma diversity) toquantify the relative contribution of individual samples, habitats, and corri-dors to the overall diversity of the three Alpine river corridors Among-sam-ple and among-corridor diversity components contributed most to total taxarichness, while <15 % was due to within-sample and among-habitat compo-nents This study clearly emphasised the importance of lateral aquatic habi-tats for maintaining high aquatic biodiversity along river corridors Conse-quently, these habitats need to be fully integrated in future conservation andrestoration projects; particularly since these are the first habitats that disap-pear as a consequence of river regulation and flow control

hierar-2.3 Reconnecting Side-Channels Along the Rhône (France)

Existing side-channels along large lowland rivers have been re-opened in anumber of cases to restore lateral connectivity Side-channels along manylarge rivers in industrialised countries have been heavily impacted by con-struction and embankment to improve navigation Embankments concen-trate the flow in the riverbed into a single straight channel and result in river-bed incision The important functions of navigation and flood control make it

no longer feasible to restore the original state of ecosystems before tion occurred As an alternative target for ecosystem rehabilitation, theincrease in biodiversity through the increase of habitat diversity between andwithin ecosystems may be used as a guiding principle to define targets inexperimental rehabilitation (Amoros 2001) This principle will be illustrated

degrada-by a project to reconnect side-channels along the Rhône River In this case,habitat diversity was enhanced by orienting the project towards the restora-tion of: (a) hydraulic connectivity (including both surface connectivity to themain river and groundwater connectivity) and (b) flooding (including waterlevel rise and scouring effects resulting in some cases from flow velocityincrease)

In the sector of the Rhône River involved, embankments made in the teenth century had led to considerable incision, while hydro-electric worksduring the twentieth century reduced the discharge to a minimum flow vary-ing from 1 % to 30 % of the base flow (Roux et al 1989) The rehabilitation pro-ject included increasing the minimum flow in the river and re-opening severalcut-off side-channels Three different approaches were evaluated: (1) GRW(GRoundWater) – a channel selected for its groundwater supply and designedwith a slope to enhance groundwater drainage, (2) BIC (BIConnected) – achannel close to the river and reconnected at both ends, (3) BKF (BacKFlow)– a channel reconnected at its downstream end in order to allow river back-