1 Global Ecology, Networks, and Research Synthesis ............ 1
1.1 Introduction ................................................ 1
1.2 Carbon and Water Cycles in the 21st Century ................. 2
1.3 Changing Biodiversity and Ecosystem Functioning ............. 3
1.4 Landscapes under Changing Disturbance Regimes ............... 3
1.5 Managing Ecosystem Services ................................. 4
1.6 Regions under Stress ........................................ 4
1.7 The Way Forward ............................................. 4
References .................................................. 5
Part A
Carbon and Water Cycles in the 21st Century ................. 7
2 CO2 Fertilization: When, Where, How Much? ................... 9
2.1 Carbon a Limiting Plant Resource? ........................... 9
2.2 Long-Term Biomass Responses and Carbon Pools ............... 10
2.2.1 Time Matters ......................................... 10
2.2.2 Nutrients and Water Determine Biomass Responses at
Elevated CO2 ......................................... 11
2.2.3 Scaling from Growth to Carbon Pools .................. 13
2.3 Carbon to Nutrient Ratios and Consumer Responses ........... 13
2.3.1 The С to N Ratio Widens .............................. 13
2.3.2 Consequences for Herbivory, Decomposition and Plant
Nutrition ............................................ 14
2.4 Plant Water Relations and Hydrological Implications ........ 14
2.5 Stress Resistance under Elevated CO2 ....................... 16
2.6 Biodiversity Effects May Outweigh Physiology Effects ....... 16
2.6.1 Hydrology Implications of Elevated CO2 Depend on
Species Abundance .................................... 16
2.6.2 Biodiversity Effects on Forest Carbon Stocking and
Grassland Responses .................................. 16
2.7 Summary and Conclusions .................................... 17
References ................................................. 18
3 Ecosystem Responses to Warming and Interacting Global
Change Factors ............................................. 23
3.1 The Multiple Factor Imperative in Global Change Research ... 23
3.2 Ecosystem Responses to Experimental Warming ................ 23
3.2.1 The GCTE-NEWS Synthesis .............................. 24
3.2.2 The ITEX Synthesis ................................... 25
3.2.3 The Harvard Forest Soil Warming Experiment ........... 26
3.3 Temperature and CO2 Interactions in Trees: the TACIT
Experiment ................................................. 26
3.3.1 Experimental Design .................................. 26
3.3.2 Growth Responses ..................................... 27
3.3.3 Higher-Order Responses ............................... 28
3.3.4 TACIT Summary ........................................ 28
3.4 More Than Two Factors: the Jasper Ridge Global Change
Experiment ................................................. 28
3.4.1 Experimental Design .................................. 28
3.4.2 Net Primary Productivity ............................. 29
3.4.3 Community Composition ................................ 29
3.4.4 JRGCE Summary ........................................ 30
3.5 Modeling Temperature, CO2 and N Interactions in Trees and
Grass ...................................................... 30
3.5.1 Global Change Simulations for a California Annual
Grassland ............................................ 30
3.5.2 Comparing Forest and Grassland with G'DAY ............ 32
3.6 Summary and Conclusions .................................... 33
Acknowledgments ............................................ 34
References ................................................. 34
4 Insights from Stable Isotopes on the Role of Terrestrial
Ecosystems in the Global Carbon Cycle ...................... 37
4.1 Introduction ............................................... 37
4.2 Ecosystem Carbon Cycles .................................... 37
4.3 The Global Carbon Cycle .................................... 40
4.4 Future Directions .......................................... 42
Acknowledgments ............................................ 42
In Memoriam ................................................ 42
References ................................................. 43
5 Effects of Urban Land-Use Change on Biogeochemical
Cycles ..................................................... 45
5.1 Introduction ............................................... 45
5.2 Urban Land-Use Change ...................................... 46
5.3 Urban Environmental Factors ................................ 47
5.3.1 Climate and Atmospheric Composition .................. 47
5.3.2 Atmospheric and Soil Pollution ....................... 49
5.3.3 Introductions of Exotic Species ...................... 49
5.4 Disturbance and Management Effects ......................... 50
5.4.1 Lawn and Horticultural Management .................... 50
5.4.2 Management Effort .................................... 51
5.5 Effects of Built Environment ............................... 52
5.6 Assessing Biogeochemical Effects - the Importance of
Scale ...................................................... 54
5.7 Summary and Conclusions .................................... 55
Acknowledgments ............................................ 56
References ................................................. 56
6 Saturation of the Terrestrial Carbon Sink .................. 59
6.1 Introduction ............................................... 59
6.2 Location of the Current Terrestrial Carbon Sinks ........... 59
6.3 Dynamics of Processes that Contribute to Carbon Sink
Saturation ................................................. 60
6.4 Processes Contributing to Terrestrial Carbon Sink
Saturation ................................................. 60
6.4.1 Processes Driven by Atmospheric Composition Change ... 60
6.4.2 Processes Driven by Climate Change ................... 64
6.4.3 Processes Driven by Land-Use Change and Land
Management ........................................... 66
6.5 Integration and Model Predictions .......................... 71
6.6 Summary and Conclusions .................................... 73
Acknowledgments ............................................ 74
References ................................................. 74
Part В
Changing Biodiversity and Ecosystem Functioning ............ 79
7 Functional Diversity - at the Crossroads between
Ecosystem Functioning and Environmental Filters ............ 81
7.1 Introduction ............................................... 81
7.2 Environmental Filters Affect FD ............................ 82
7.3 FD effects on Global Change Drivers ........................ 82
7.3.1 The Traits of the Dominants .......................... 82
7.3.2 The Role of Interactions ............................. 87
7.4 Summary and Conclusions .................................... 89
Acknowledgments ............................................ 89
References ................................................. 90
8 Linking Plant Invasions to Global Environmental Change ..... 93
8.1 Introduction ............................................... 93
8.2 Plant Invasions and Elevated CO2 ........................... 93
8.3 Plant Invasions and Climatic Change ........................ 95
8.4 Plant Invasions and Land Eutrophjjrfftion .................. 96
8.5 Plant Invasions and Changes in Land Use/Cover .............. 97
8.6 Multiple Interactions ...................................... 98
8.7 Summary and Conclusions .................................... 99
Acknowledgments ............................................ 99
References ................................................. 99
9 Plant Biodiversity and Responses to Elevated Carbon
Dioxide ................................................... 103
9.1 Ten Years of GCTE Research: Apprehending Complexity ....... 103
9.1.1 Effects of CO2 on Plant Diversity Through
Alterations of the Physical Environment ............. 103
9.2 Temporal Variation and Response to Elevated CO2 ........... 105
9.2.1 Reproductive and Evolutionary Aspects of
the Response to Elevated CO2 ........................ 105
9.2.2 Communities at Equilibrium Versus Dynamic Systems ... 105
9.3 Biodiversity Loss and Response to Elevated CO2 ............ 107
9.3.1 Species Diversity and Response to Elevated CO2 ...... 107
9.3.2 Ecosystem С Fluxes in a Species-Poor World .......... 108
9.4 Summary and Conclusions ................................... 110
References ................................................ 111
10 Predicting the Ecosystem Consequences of Biodiversity
Loss: the Biomerge Framework ............................. 113
10.1 Biodiversity and Ecosystem Functioning: a Synthesis ...... 113
10.1.1 Why Biodiversity Matters to Global Change
Ecology ........................................... 113
10.1.2 Linking Change in Biodiversity with Change in
Ecosystem Functioning ............................. 114
10.1.3 Lessons Learned from Early Debates ................ 114
10.1.4 What We Have Learned about the Relationship
between Biodiversity and Ecosystem Function ....... 115
10.1.5 The Scientific Framework for Linking
Biodiversity and Ecosystem Functioning ............ 115
10.2 The BioMERGE Framework ................................... 117
10.2.1 The BioMERGE Structural Sub-Framework ............. 117
10.2.2 The BioMERGE BEF Sub-Framework: an Expansion of
the Vitousek-Hooper Framework ..................... 117
10.2.3 The BioMERGE Research Implementation
Sub-Framework ..................................... 119
10.3 Discussion: Towards a Large Scale BEF .................... 122
Acknowledgments .......................................... 123
References ............................................... 123
Part C
Landscapes under Changing Disturbance Regimes ............ 127
11 Plant Species Migration as a Key Uncertainty in
Predicting Future Impacts of Climate Change on
Ecosystems: Progress and Challenges ...................... 129
11.1 Introduction ............................................. 129
11.2 Will Migration Be Necessary for Species Persistence? ..... 130
11.2.1 Vegetation-Type Models ............................ 131
11.2.2 Species-Based Models .............................. 132
11.3 Measurements and Models of Migration Rates ............... 133
11.4 Linking Migration and Niche Based Models ................. 134
11.5 Summary and Conclusions .................................. 135
Acknowledgments .......................................... 135
References ............................................... 135
12 Understanding Global Fire Dynamics by Classifying and
Comparing Spatial Models of Vegetation and Fire .......... 139
12.1 Introduction ............................................. 139
12.2 Background ............................................... 140
12.3 Model Classification ..................................... 140
12.4 Model Comparison ......................................... 141
12.4.1 The Models ........................................ 141
12.4.2 The Comparison Design .................................. 143
12.5 Results and Discussion ................................... 144
12.5.1 Model Classification .............................. 144
12.5.2 Model Comparison .................................. 145
12.6 Summary and Conclusions .................................. 145
Acknowledgments .......................................... 146
References ............................................... 146
13 Plant Functional Types:
Are We Getting Any Closer to the Holy Grail? ............. 149
13.1 In Search of the Holy Grail .............................. 149
13.2 Individual Plant Structure and Function .................. 149
13.3 Traits and Environmental Gradients ....................... 152
13.3.1 Plant Functional Response to Mineral Resource
Availability ...................................... 152
13.3.2 Plant Functional Response to Disturbance .......... 152
13.3.3 Projecting Changes in Plant Functional Traits in
Response to Global Change ......................... 154
13.4 Scaling from Individual Plants to Communities:
from Response Traits to Community Assembly ............... 155
13.5 Scaling from Communities to Ecosystems:
from Response Traits to Effect Traits .................... 156
13.6 So, Are We Getting Closer to the Holy Grail?
Scaling beyond Ecosystems ................................ 157
13.6.1 Plant Functional Traits and Landscape Dynamics .... 157
13.6.2 Regional to Global Models -
Revisiting the Early Functional Classifications ... 157
13.6.3 Validation: the Contribution of Paleo-Data ........ 158
13.7 Summary and Conclusions .................................. 159
Acknowledgments .......................................... 159
References ............................................... 159
14 Spatial Nonlinearities: Cascading Effects in the Earth
System ................................................... 165
14.1 Introduction ............................................. 165
14.2 Conceptual Framework ..................................... 166
14.3 Insights to Global Change Issues ......................... 166
14.3.1 Historical Example: the Dust Bowl of the 1930s .... 166
14.3.2 Wildfire .......................................... 168
14.3.3 Invasive Species and Desertification .............. 171
14.4 Forecasting Spatial Nonlinearities and Catastrophic
Events ................................................... 172
14.5 Summary and Conclusions .................................. 173
Acknowledgments .......................................... 173
References ............................................... 173
15 Dynamic Global Vegetation Modeling:
Quantifying Terrestrial Ecosystem Responses to
Large-Scale Environmental Change ......................... 175
15.1 Introduction ............................................. 175
15.2 Historical Antecedents and Development of DGVMs .......... 175
15.2.1 Plant Geography ................................... 176
15.2.2 Plant Physiology and Biogeocbemistry .............. 176
15.2.3 Vegetation Dynamics ............................... 177
15.2.4 Biophysics ........................................ 177
15.2.5 Human Intervention ................................ 178
15.3 Principles and Construction of DGVMs ..................... 178
15.3.1 Model Architecture ................................ 178
15.3.2 Net Primary Production ............................ 179
15.3.3 Plant Growth and Vegetation Dynamics .............. 179
15.3.4 Hydrology ......................................... 180
15.3.5 Soil Organic Matter Transformations ............... 180
15.3.6 Nitrogen (N) Cycling .............................. 180
15.3.7 Disturbance ....................................... 180
15.4 Evaluating DGVMS ......................................... 181
15.4.1 Net Primary Production ............................ 181
15.4.2 Remotely Sensed "Greenness" and Vegetation
Composition ....................................... 181
15.4.3 Atmospheric CO2 Concentration ..................... 181
15.4.4 Runoff ............................................ 182
15.4.5 CO2 and Water Flux Measurements ................... 182
15.5 Examples of Applications of DGVMS ........................ 182
15.5.1 Holocene Changes in Atmospheric CO2 ............... 182
15.5.2 Boreal "Greening" and the Contemporary Carbon
Balance ........................................... 182
15.5.3 The Pinatubo Effect ............................... 183
15.5.4 Future Carbon Balance Projections ................. 183
15.5.5 Carbon-Cycle Feedbacks to Future Climate Change ... 183
15.5.6 Effects of Land-Use Change on the Carbon Cycle .... 185
15.6 Some Perspectives and Research Needs ..................... 185
15.6.1 Comparison with Field Experiments ................. 185
15.6.2 Plant Functional Types ............................ 185
15.6.3 The Nitrogen Cycle ................................ 185
15.6.4 Plant Dispersal and Migration ..................... 186
15.6.5 Wetlands .......................................... 186
15.6.6 Multiple Nutrient Limitations ..................... 186
15.6.7 Agriculture and Forestry .......................... 186
15.6.8 Grazers and Pests ................................. 186
15.6.9 Biogenic Emissions of Trace Gases and Aerosol
Precursors ........................................ 187
15.7 Summary and Conclusions .................................. 187
References ............................................... 187
Part D
Managing Ecosystem Services .............................. 193
16 Wheat Production Systems and Global Climate Change ....... 195
16.1 Introduction ............................................. 195
16.2 Global Atmospheric Change, Climate and Yields ............ 197
16.3 Impacts on Wheat Productivity ............................ 199
16.4 Addressing the Yield Gap ................................. 200
16.5 The Protein Gap .......................................... 200
16.6 The Rice-Wheat System .................................... 201
16.7 The Effect of Climate Change on the Rice-Wheat System .... 202
16.8 The Contribution of the Rice-Wheat System to Climate
Change ................................................... 202
16.9 Carbon Dioxide ........................................... 203
16.10 Methane ................................................. 203
16.11 Nitrous Oxide ........................................... 204
16.12 Comparative Greenhouse Gas Budgets for Rice-Wheat
Farming Systems ......................................... 204
16.13 Summary and Conclusions ................................. 207
References .............................................. 208
17 Pests Under Global Change - Meeting Your Future
Landlords? ............................................... 211
17.1 Introduction ............................................. 211
17.2 Methods .................................................. 211
17.2.1 IPCC Processes .................................... 211
17.2.2 Monitoring, Benchmarks and Indicators for
Measuring Impacts ................................. 212
17.2.3 Estimating Impacts ................................ 213
17.3 Impacts .................................................. 216
17.3.1 Atmospheric CO2 and Climate ....................... 216
17.3.2 Land Use, Land Cover and Biodiversity ............. 219
17.3.3 Trade and Travel .................................. 219
17.4 Adaptation ............................................... 220
17.4.1 Natural Adaptations ............................... 220
17.4.2 Adaptive Management Options ....................... 220
17.4.3 Adaptation of Control Measures in Response to
Global Change ..................................... 221
17.4.4 Threats to Sustainability of Adaptation Options ... 221
17.5 Vulnerability ............................................ 222
17.6 Summary and Conclusions .................................. 222
References ............................................... 223
18 Greenhouse Gas Mitigation Potential in Agricultural
Soils .................................................... 227
18.1 Introduction ............................................. 227
18.1.1 Soil Carbon and Carbon Dioxide .................... 227
18.1.2 Trade-Offs between GHGs in Agriculture ............ 227
18.2 What Is Meant by GHG Mitigation Potential? ............... 229
18.3 Regional Case Studies .................................... 230
18.3.1 Sustainable Soil Management in the Moscow Region
to Enhance Soil Carbon ............................ 230
18.3.2 Soil Carbon Sequestration Potential in the US ..... 231
18.4 Carbon Sequestration in the Future ....................... 232
18.5 Win-Win Strategies for Greenhouse Gas Mitigation by
Agricultural Soils ....................................... 232
18.6 Future Challenges ........................................ 233
18.6.1 Improving Carbon Sequestration .................... 233
18.6.2 Monitoring Soil Carbon Sequestration .............. 233
18.7 Summary and Conclusions .................................. 234
References ............................................... 235
19 Carbon and Water Tradeoffs in Conversions to Forests
and Shrublands ........................................... 237
19.1 Introduction ............................................. 237
19.2 Afforestation ............................................ 237
19.2.1 Afforestation: Carbon Storage Potential ........... 237
19.2.2 Afforestation: Evapotranspiration and Water
Yield ............................................. 238
19.2.3 Afforestation: Potential Atmospheric Feedbacks .... 239
19.3 Woody Encroachment and Agriculture ....................... 240
19.3.1 Grassland Conversions with Woody Plant
Encroachment and Agriculture ...................... 240
19.3.2 Processes Controlling Soil С Storage:
Grassland Vs. Woodland ............................ 241
19.3.3 Uncertainties in Water and Carbon Balances with
Woody Plant Encroachment .......................... 242
19.4 Summary and Conclusions .................................. 243
References ............................................... 244
20 Natural and Human Dimensions of Land Degradation in
Drylands: Causes and Consequences ........................ 247
20.1 Introduction ............................................. 247
20.2 Drylands, Desertification, Drivers, and Scales ........... 247
20.2.1 Distribution of People and Land-Cover Types ....... 247
20.2.2 Defining Land Degradation and Desertification ..... 248
20.2.3 What Drives Land Degradation and
Desertification? .................................. 249
20.2.4 Estimating the Extent of Desertification .......... 249
20.2.5 Consequences of Desertification ................... 250
20.2.6 Scale and Hierarchy ............................... 251
20.3 Joint GCTE-LUCC Desertification Initiative ............... 252
20.3.1 Dahlem Desertification Paradigm ................... 252
20.3.2 Initiatives to Test the Dahlem Desertification
Paradigm .......................................... 253
20.4 Management of Desertified Drylands ....................... 254
20.4.1 Avoidance ......................................... 254
20.4.2 Monitoring ........................................ 254
20.4.3 Restoration ....................................... 254
20.5 Summary and Conclusions .................................. 255
Acknowledgments .......................................... 255
References ............................................... 255
Part E
Regions under Stress ..................................... 259
21 Southeast Asian Fire Regimes and Land Development
Policy ................................................... 261
21.1 Introduction ............................................. 261
21.2 Underlying Causes of Land Fires .......................... 262
21.2.1 Explaining Fire Occurrence ........................ 262
21.2.2 Land Development Policies ......................... 262
21.2.3 Land Management Practices ......................... 263
21.2.4 Property Rights and Conflicts ..................... 265
21.3 Landscape, Regional and Global Interactions .............. 265
21.3.1 Ecosystem Dynamics ................................ 265
21.3.2 Regional Haze Episodes ............................ 266
21.3.3 Greenhouse Gas Emissions .......................... 266
21.3.4 Interactions with Climate Variability and
Change ............................................ 267
21.4 Human Weil-Being ......................................... 267
21.4.1 Economic and Health Impacts ....................... 267
21.4.2 Livelihoods ....................................... 267
21.5 Informed Decision-Making and Better Governance ........... 268
21.5.1 Role of Expertise ................................. 268
21.5.2 Regional Cooperation .............................. 269
21.6 Summary and Conclusions .................................. 269
Acknowledgments .......................................... 270
References ............................................... 270
22 Global Change Impacts on Agroecosystems of Eastern
China .................................................... 273
22.1 Introduction ............................................. 273
22.2 Chinese Terrestrial Transects ............................ 274
22.3 Physiological and Plant Responses to Multiple Global
Change Forcing ........................................... 275
22.4 Productivity and Its Responses to Global Change .......... 276
22.5 Carbon Budget and Its Responses to Global Change ......... 278
22.6 Summary and Conclusions .................................. 282
Acknowledgments .......................................... 282
References ............................................... 282
23 Terrestrial Ecosystems in Monsoon Asia:
Scaling up from Shoot Module to Watershed ................ 285
23.1 Introduction ............................................. 285
23.2 Responses of Plant Communities to the Global Change:
Scaling from Leaf to Landscape Through Individual
Plant .................................................... 285
23.2.1 Competition among Individual Plants in Even-Aged
Monospecific Stands at Elevated CO2 ............... 286
23.2.2 Shoot-Module-Based Simulator As a Tool of
Individual Tree Response .......................... 288
23.2.3 Modeling the Shift of Forest Zonation ............. 289
23.3 Carbon Budget at the Forest Watershed Scale .............. 289
23.3.1 Carbon Exchange between Atmosphere-Forest-Stream
Boundaries ........................................ 290
23.3.2 Transport of Dissolved Organic Carbon Associated
with Dissolved Nitrogen from Terrestrial to
Aquatic Ecosystems ................................ 290
23.3.3 Dynamics of Dissolved Organic Carbon at
the Interface of Stream and Lake Ecosystems ....... 291
23.4 Carbon Budget and Functions of the Lake Biwa Ecosystem ... 292
23.4.1 Carbon Budget in the Lake ......................... 292
23.4.2 Metabolism in the Lake Sediments .................. 293
23.4.3 Terrestrial Environment and Function of Lake
Ecosystems ........................................ 293
23.5 Summary and Conclusions .................................. 294
References ............................................... 294
24 Responses of High Latitude Ecosystems to Global Change:
Potential Consequences for the Climate System ............ 297
24.1 Introduction ............................................. 297
24.2 Recent Changes in Climate, Disturbance Regimes, and
Land Cover ............................................... 297
24.3 Responses of Radiatively Active Gases .................... 300
24.3.1 General Issues .................................... 300
24.3.2 Responses of CO2 Exchange to Climatic Change ...... 300
24.3.3 Responses of CH4 Exchange to Climatic Change ...... 302
24.3.4 Responses to Changes in Disturbance and Land
Cover ............................................. 303
24.4 Responses of Water and Energy Exchange ................... 304
24.4.1 General Issues .................................... 304
24.4.2 Responses to Changes in Climate, Disturbance,
and Land Cover .................................... 304
24.5 Delivery of Freshwater to the Arctic Ocean ............... 305
24.5.1 General Issues .................................... 305
24.6 Summary and Conclusions .................................. 305
References ............................................... 306
Part F
Future Directions: the Global Land Project ............... 311
25 The Future Research Challenge: the Global Land Project ... 313
25.1 Introduction ............................................. 313
25.2 Research Objectives ...................................... 314
25.3 Emergent Concepts ........................................ 315
25.3.1 Land-Use Decision Making and Adaptive
Management ........................................ 315
25.3.2 Ecosystem Services ................................ 316
25.3.3 Vulnerability and Sustainability Science .......... 316
25.4 Research Framework ....................................... 317
25.4.1 Theme 1: Dynamics of Land System .................. 317
25.4.2 Theme 2: Consequences of Land-System Change ....... 318
25.4.3 Theme 3: Integrating Analysis and Modeling for
Land Sustainability ............................... 318
25.5 Implementation Strategy .................................. 319
25.6 Summary and Conclusions .................................. 320
References ............................................... 321
Index .................................................... 323
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