Biodiversity and Ecosystem Function

Ernst-Detlef Schulze Harold A. Mooney (Eds.) Biodiversity and Ecosystem Function With 116 Figures, 7 Color Plates and 22 Tables Springer-Verlag Berlin Heidelberg New York London Paris Tokyo Hong Kong Barcelona Budapest

Contents Section A: Ecosystem Function 1 Biological Diversity and Terrestrial Ecosystem Biogeochemistry P. M. Vitousek and D. U. Hooper 3 1.1 Introduction 3 1.2 Semantics 4 1.3 Biological Diversity and Biogeochemistry 5 1.3.1 Experimental Tests 6 1.3.2 Biogeographic Patterns 9 1.4 Other Potential Effects of Plant Diversity on Biogeochemistry 10 1.5 Conclusions 11 References 12 2 Biodiversity and Ecosystem Function in Agricultural Systems M. J. Swift and J. M. Anderson 15 2.1 Introduction 15 2.2 Characteristics of Agricultural Ecosystems 16 2.2.1 Diversity and Complexity > 16 2.2.2 Classification in Relation to Diversity and Complexity 19 2.2.3 Sustainability :. 21 2.3 Productive Attributes of Low Number Multiple Cropping Systems 22 2.4 Biodiversity and the Function of the Decomposer Subsystem 25 2.4.1 Biodiversity in Relation to Function '.:.. 25 2.4.2 Decomposer Diversity and Function in Agricultural Systems 28 2.4.3 Interactions Between Plants and the Soil Biota 30 2.5 Biodiversity and the Function of the Herbivore Subsystem 32 2.6 Conclusions 33 2.6.1 A Hypothesis of the Importance of Plant Diversity in Ecosystem Regulation 33

XIV Contents 2.6.2 The Importance of Increasing Plant Species Number. 36 2.6.3 The Importance of Plant Species Composition 37 2.6.4 Assessment of Long-Term Trends 38 References 38 3 Biodiversity and Interactions Within Pelagic Nutrient Cycling and Productivity C.E.W. Steinberg and W. Geller 43 3.1 Introduction: Explanations to the Paradox of the Plankton 43 3.2 Further Determinants of Biodiversity 44 3.2.1 Plasticity and Cell Shape 44 3.2.2 Turbulence 45 3.3 Selection and Succession 46 3.3.1 Descriptive Model of Plankton Succession 47 3.4 Microbial Loop: Structure and Function 50 3.4.1 Structure 50 3.5 Structural Diversity Indices 55 3.6 Ataxonomic Approach to Assess Ecosystem Stability. VJ57 3.7 Conclusions 60 References 61 Section B: Functional Groups 4 Functional Groups of Microorganisms O. Meyer 67 4.1 Introduction 67 4.2 Free-Living Components of the Soil Microbiota 68 4.3 Metabolic Types of Bacteria 71 4.4 The Role of Microorganisms in the Decomposition of Organic Material 73 4.4.1 Cellulose 75 4.4.2 Lignin 76 4.4.3 Proteins, Peptides, and Amino Acids 77 4.4.4 Pectin 78 4.5 The Role of Microorganisms in the Biogeochemical Cycle of Nitrogen 79 4.5.1 Nitrification 79 4.5.2 Denitrification 82 4.5.3 N 2 Fixation i 84 4.6 The Role of Microorganisms in the Biogeochemical Cycle'of Sulfur 86 4.6.1 The Oxidation of Reduced Sulfur Compounds 86 4.6.2 Desulfurication 88

Contents XV 4.7 Conclusions 90 References. 93 5 Plant Traits and Adaptive Strategies: Their Role in Ecosystem Function O.T. Solbrig 97 5.1 Introduction 97 5.2 Schemes to Classify Plants on the Basis of Their Ecological Traits 97 5.2.1 Single-Character Functional Classification of Vascular Plants 99 5.2.2 Attempts to Classify Species Based on Their Overall Ecological Adaptability, 101 5.3 Adaptive Strategies 101 5.3.1 Optimization 103 5.3.2 Plant Adaptive Strategies 103 5.3.3 Why Optimality Criteria Are Not Always Sufficient.. 106 5.4 Definition of Ecosystem Functional Properties 108 5.5 The Meaning of Adaptive Strategy in a Complex, Nonlinear World 108 5.6 Conclusions: The Importance of Diversity in a Nonequilibrium Situation 110 References Ill 6 Scaling from Species to Vegetation: The Usefulness of. Functional Groups Ch. Korner 117 6.1 Introduction: What Are Functional Groups and Why Use Them? 117 6.2 Selecting Functional Groups 118 6.3 Narrow or Wide Grouping: The Dilemma of ; Experimental Safety and Ecological Applicability 120 6.4 Grouping of Plant Species with Respect to Their Structural, Physiological, and Life Strategy Characteristics 121 6.4.1 Life-Forms and Structures: The Morphotype 121 6.4.2 Dry Matter Partitioning: Investment Type 122 6.4.3 The Physiotype...: 123 6.4.4 The Physiomorphotype 124 6.4.5 Life Strategies 125 6.5 The Spatial Definition of Functional Groups within Plant Communities 127 6.6 Ecosystems: The Largest Functional Group 130 6.7 Integration of Contrasting Levels of Complexity: A Compromise 131

XVI Contents 6.8 A Promising Tool: Using Functional Groups in Controlled Ecosystems 133 6.9 Conclusions 136 References 137 Section C: Species Interaction 7 Evolution of Functional Groups in Basidiomycetes (Fungi) F. Oberwinkler 143 7.1 Introduction 143 7.2 What Are Fungi? 143 7.2.1 Yeasts and Dimorphic Fungi 144 7.3 Functional Fungal Groups 145 7.4 Evolution of Fungal Parasites of Plants 145 7.5 Evolution in Diverse Wood-Decaying Fungi 148 7.5.1 Saprobic Fungi 149 7.6 Evolution in Symbiontic Basidiomycetes 149 7.6.1 Basidiolichens 150 7.6.2 Mycorrhizae 150 7.7 Diversity and Coevolutionary Trends in Septobasidiales 151 7.8 Conclusions 162 References 163 8 The Role of Parasites in Plant Populations and Communities J. J. Burdon 165 8.1 Introduction 165 8.2 The Diversity and Specialization of Parasites and Their Effects on the Fitness of the Host Plant 166 8.2.1 Parasitic Plants" 166 8.2.2 Fungal and Viral Pathogens 167 8.3 The Hidden Effects of Parasite Attack - Changes in the Genetic Structure of Plant Populations 17Q 8.4 Parasite Attack as a Determinant of Ecosystem Structure 171 8.4.1 Lessons from Exotic Pathogens and Severely Disturbed Natural Systems 172 8.4.2 Evidence from Natural Parasite-Host Associations... 175 8.5 Conclusions 177 References 177

Contents XVII 9 Plant-Microbe Mutualisms and Community Structure D.J. Read 181 9.1 Introduction 181 9.2 Plant-Microbe Mutualisms in Grassland Communities 183 9.3 Plant-Microbe Mutualisms in Savanna and Tropical Forest Communities 188 9.4 Plant-Microbe Mutualisms in Boreal and Temperate Forest Communities 190 9.5. Plant-Microbe Mutualisms in Heathland and Related Wetland Ecosystems 196 9.6 The Role of Mutualisms in Successional Processes... 199 9.7 Conclusions 202 References 203 10 The Evolution of Interactions and Diversity in Plant- Insect Systems: The Urophora-Eurytoma Food Web in Galls on Palearctic Cardueae H. Zwolfer and J. Arnold-Rinehart 211 10.1 Introduction 211 10.2 The Urophora Food Web 212 10.2.1 General Ecological Characteristics of the Urophora- Eurytoma System 214 10.2.2 Structure and Evolution of the Urophora Gall 215-10.2.3 The Effect of the Gall Size on the Two Eurytoma spp. 219 10.3 Resource Exploitation, Interactions, and Evolution... 221 10.3.1 The Evolution of Diversity at the Herbivore Level of Plant-Insect Systems 221 10.3.2 Host P'lants as Underexploited Resources 222 10.3.3 Exploitation Strategies in the Urophora-Eurytoma System 223 10.3.4 Interaction Patterns at the Second and Third Trophic Level: Evolutionary Adjustments in Food Webs \ 224 10.4 Conclusions 226 References 227 Appendix 231 Section D: Community Interactions 11 Keystone Species W. J. Bond 237 11.1 Introduction 237 11.2 History of the Concept 238 11.3 The Different Kinds of Keystone Species 238

XVIII Contents 11.3.1 Keystone Predators 239 11.3.2 Keystone Herbivores 241 11.3.3 Keystone Pathogens 242 11.3.4 Keystone Competitors 242 11.3.5 Keystone Mutualists 243 11.3.6 Earth-movers 245 11.3.7 System Processes 245 11.3.8 Abiotic Processes 246 11.3.9 Summary of Types of Keystone Species 246 11.4 Identifying Keystone Species 247 11.4.1 Towards a General Protocol 248 11.5 Which Keystone Species Are Vulnerable? 249 11.6 Conclusions 249 References 250 12 Redundancy in Ecosystems J. H. Lawton and V. K. Brown 255 12.1 Introduction 255 12.2 Evidence from the Fossil Record 256 12.3 Patterns of Energy Flow, Biomass and the Structure of Food Webs 257 12.3.1 Productivity and Biomass 257 12.3.2 Food Webs 258 12.4 Theoretical Models of Ecosystem Stability and Resilience 259 12.4.1. Species Deletion Stability 260 12.4.2 Possible Modelling Approaches 261 12.5 Observations and Experiments on Real Systems 261 12.5.1 Species Richness and Population Fluctuations 261 12.5.2 Keystone Species 262 12.5.3 Manipulation Experiments: General Considerations... 263 12.5.4 Manipulation Experiments: Examples ; 264 12.6 Conclusions 266 References 268 13 How Many Species Are Required for a Functional Ecosystem? F. I. Woodward 271 13.1 Introduction : 271 13.1.1 Ecosystems 271 13.2 Species Diversity and Ecosystem Properties 272 13.2.1 Introduction 272 13.2.2 Species Enumerations and Ecosystem Functions 273 13.2.3 The Inequality of Species in Ecosystem Function... 276 13.2.4 Species Diversity and Ecosystem Stability 277 13.2.5 Species Numbers and Dynamics: Year-to-Year Averaging 279

Contents XIX 13.2.6 Species Numbers and Dynamics: Species Feedbacks.. 281 13.3 Species Diversity and Ecosystem Dynamics 283 13.3.1 Introduction 283 13.3.2 Experiments 284 13.3.3 Modelling 286 13.4 Conclusions 287 References 289 14 Rare and Common Plants in Ecosystems, with Special Reference to the South-west Australian Flora J.S. Pate and S.D. Hopper 293 14.1 Introduction 293 14.2 Species Rareness or Commonness and Niche Specialization in Terms of Habitat and Nutritional Preference 298 14.3 Fire as a Factor in Species Commonness and Rarity.. 300 14.3.1 Strictly Serotinous Obligate Seeder Shrub or Tree Species 302 14.3.2 Non-Serotinous or Partially Serotinous Obligate Seeder Shrub or Tree Species 303 14.3.3 Obligate Seeder Species with Soil-Based Seed Reserves 303 14.3.4 Resprouter Species of High Recruitment Potential... 304 14.3.5 Long-Lived, Clonally Reproducing Resprouter Species of Strictly Limited Recruitment Potential 305 14.3.6 Fire Ephemerals 306 14.3.7 Geophytes 308 14.4 The Significance of Morphological and Physiological Variation to Commonness or Rareness of Species... 308 14.5 Evaluation of Commonness and Rareness in Related Taxonomic Groupings 310 14.6 The Importance of Biotic Factors in Species Commonness or Rareness ; 312 14.7 Genetic Correlates of Commonness and Rarity 314 14.8 Conclusions :.. 318 References 320 15 Community Diversity and Succession: The Roles of Competition, Dispersal, and Habitat Modification D. Tilman 327 15.1 Introduction 327 15.2 Succession 328 15.2.1 Environmental Constraints 328 15.2.2, Interspecific Trade-offs 329 15.2.3* Successional Theories 330 15.2.4 Successional Dynamics and the Existing Species Pool. 335 15.3 Biotic Diversity 337

XX Contents 15.3.1 Spatial Heterogeneity 337 15.3.2 Local Recruitment Limitation 338 15.3.3 Succession and Biodiversity 338 15.3.4 Constraints, Trade-offs, and the Conservation of Biodiversity 339 15.4 Conclusions 341 References 341 Section : Ecosystem Integrity 16 Biodiversity and the Balance of Nature S. L. Pimm 347 16.1 What Biodiversity is Good for 347 16.2 A History of Ecological Stability 348 16.2.1 Controversy 349 16.3 The Stability of Populations 351 16.3.1 Resilience: The Example of Pest Outbreaks 351 16.3.2 Year-to-Year Variability in Densities 352 16.4 The Persistence of Communities 353 16.4.1 Extinction 355 16.4.2 Invasions 355 16.5 Resistance to Change 357 16.6 Conclusions " 358 'References 359 17 Biodiversity and Function of Grazing Ecosystems S. J. McNaughton 361 17.1 Introduction 361 17.1.1 Intellectual Origins 361 17.1.2 Conceptual Development 362 17.1.3 An Individual Remark 363 17.2 Theory and Empiricism 364 17.2.1 Conceptual Definitions 364 17.3 How to Test 366 17.4 Tests 367 17.4.1 Diversity and Productivity 367 17.4.2 Diversity and Stability 369 17.5 Stability of Species Composition to Drought and Grazing: Yellowstone Grazing Ecosystem 378 17.6 Conclusions: Biodiversity and Ecosystem Function... 379 17.6.1 Biodiversity, Productivity, and Stability 379 17.6.2 Biodiversity, System Perpetuation, and Global Change 380 References 382

Contents XXI 18 Resource Supply and Disturbance as-controls over Present and Future Plant Diversity S.E. Hobbie, D.B. Jensen, and F.S. Chapin, III 385 18.1 Introduction 385 18.2 Future Resource and Disturbance Regimes 385 18.3 Plant Genetic Diversity 387 18.3.1 Patterns of Genetic Diversity 388 18.3.2 Land-Use Changes and Habitat Fragmentation 389 18.3.3 Climatic Effects 390 18.3.4 Resource Availability 391 18.4 Plant Species Diversity 392 18.4.1 Regional Patterns 392 18.4.2 Latitudinal Patterns 394 18.4.3 Paleoecological Patterns 394 18.4.4 Future Changes 395 18.5 Diversity of Plant Functional Groups 396 18.5.1 General Considerations 396 18.5.2 Control by Resourcesand Disturbance 398 18.5.3 Types of Functional Groups 399 18.5.4 Climatic Predictors 400 18.5.5 Future Diversity 401 18.6. Landscape Diversity 403 18.7 Consequences of Changing Biodiversity 403 18.8 Conclusions 404 References. 405 19 Ecosystem Stability, Competition, and Nutrient Cycling F. Berendse 409 19.1 Introduction 409 19.2 Stability of Model Ecosystems, 410 19.3 Competition and the Loss of Diversity : 413 19.4 Stabilizing Consequences of Competitive Interactions. 414 19.5 Effects of Organisms on Their Physical Environment. 419 19.6 Features Affecting Plant Fitness Under Different Nutrient Supply Conditions 421 19.7 Consequences of the Different Effects of Plant Species on the Nutrient Cycle 423 19.8 Conclusions 427 References 428 20 t Modelling Biodiversity: Latitudinal Gradient of Forest Species Diversity Y. Iwasa, K. Sato, M. Kakita, and T. Kubo 433 20.1 Introduction 433

XXII Contents 20.2 Hypotheses Explaining the Variation of Species Diversity 434 20.2.1 Specialization of Resource Use 434 20.2.2 Mode of Disturbance 434 20.2.3 Smaller Opportunity for Competition 435 20.2.4 Productivity 436 20.2.5 Specific Herbivores and Pathogens 436 20.2.6 Evolutionary/Ecological History 436 20.3 Tree-byrTree Replacement: Finite Population Models.. 437 20.3.1 Spatial Scale of Disturbance and Dispersal 438 20.3.2 Inhibited Regeneration 439 20.3.3 Temporal Fluctuation of Regeneration Ability 441 20.4 Species Packing to Temporal Niches: Infinite Population Models 441 20.4.1 Model 442 20.4.2 Species Diversity Versus the Length of the Unfavorable Season 443 20.4.3 Species Diversity Versus Niche Width 444 20.4.4 Phenology of Coexisting Species 445 20.5 Conclusions 447 References 449 21 Functional Aspects of Landscape Diversity: A Bavarian Example E.-D. Schulze and P. Gerstberger 453 21.1 Introduction 453 21.2 Geology and Vegetation 453 21.3 Land Use in Northeast Bavaria 454 21.3.1 Hedgerows 456 21.3.2 Grasslands 461 21.3.3 Forests 462 21.4 Conclusions 464 References 465 Section F: Industrial Analogy and Policy 22 Biodiversity Issues in Computing: A Study of Networked Computer Viruses C. Partridge and C. Malmstrom 469 22.1 Introduction 469 22.2 Stable Distributed Computer Systems 470 22.3 Computer Viruses 471 22.3.1 Duff's Virus 471 22.3.2 The Morris Virus 472

Contents XXIII 22.4 Diversity and the Spread of a Networked Virus 473 22.4.1 A Simple Mathematical Model 473 22.4.2 Functional Diversity 475 22.4.3 Species Diversity 477 22.5 Conclusions,479 References 479 23 Biodiversity and Policy Decisions L.F. Pitelka 481 23.1 Introduction 481 23.2 Conserving Biodiversity 482 23.3 Global Climate Change 483 23.4 Ecological Research and Policy Decisions 485 23.5 Providing Policy-Relevant Research Results 486 23.6 Conclusions 492 References 492 Conclusion 24 Ecosystem Function of Biodiversity: A Summary E.-D. Schulze and H.A. Mooney 497 24.1 Introduction 497 24.2 What Is an Ecosystem? 497 24.3 The Regulation of Ecosystem Processes 499 24.4 Are There Functional Groups? 501 24.5 Determinants of Species Numbers 503 24.6 Ecosystem Integrity 506 24.7 Effects of Global Change on Land Use and Climate. 506 24.8 Conclusions 507 References ;, 509 Species Index 511 Subject Index 521