ECOSYSTEM DYNAMICS OF THE BOREAL FOREST The Kluane Project

Transcription

1 ECOSYSTEM DYNAMICS OF THE BOREAL FOREST The Kluane Project Edited by Charles J. Krebs Stan Boutin Rudy Boonstra OXFORD UNIVERSITY PRESS 2001

2 Contents Contributors xxi PART I INTRODUCTION 1 General Introduction CHARLES J. KREBS 3 2 The Kluane Region CHARLES J. KREBS & RUDY BOONSTRA Geography and Geology, Weather and Climate, Temperature, Precipitation, Study Area and Vegetation, Vertebrate Food Web, History of Hare Cycles, Large Mammals, Human Impacts, 23 3 Trophic Interactions, Community Organization, and the Kluane Ecosystem A. R. E. SINCLAIR & CHARLES J. KREBS Trophic-level Theory,^/ Community Structure, Control of Trophic-level Biomass, Case Studies in Mammalian Communities, Interactions of Trophic Levels, Bottom-up Models, 36

3 xii CONTENTS Top-down Models, Herbivore-dominated Models, Vegetation-dominated Models, Dilution Models, Reciprocal Models, Experimental Perturbations in the Boreal Forest, Experiment 1: Application of Fertilizer, Experiment 2: Addition of Rabbit Chow, Experiment 3: Exclusion of Carnivores, Experiment 4: Exclusion of Carnivores and the Addition of Rabbit Chow, Experiment 5: Exclusion of Hares, Experiment 6: Exclusion of Hares and the Addition of Fertilizer, Experiment 7: Removal of Vegetation, Discussion, Limitations of the Models, Models of Trophic-level Interactions in Different Ecosystems, Summary, 43 Experimental Design and Practical Problems of Implementation STAN BOUTIN, CHARLES J. KREBS, VILIS O. NAMS, A. R. E. SINCLAIR, RUDY BOONSTRA, MARK O'DONOGHUE, & CATHY DOYLE Experimental Design, Choice of Treatments, Size and Spatial Location of Treatments, To Replicate or Not to Replicate, Practical Problems of Implementation, The Evolution of a Predator-proof Fence, Food Supplementation, Fertilizer, Hare Exclosures, Organization, Personnel, and Equipment, Organizational Structure, The Problem of Training and Protocols, Seen Sheets, Winter Work at Kluane, Equipment, Summary, 65 PART II PLANT DYNAMICS ' Herbs and Grasses. ROY TURKINGTON, ELIZABETH JOHN, & MARK R. T. DALE / Hypotheses Regarding Vegetation, Study Area, Tests of Predictions from Three Models, Donor Control Model, 72

4 CONTENTS xiii Herbivore Control Model, Combined Top-down Bottom-up Model, Which Model Best Describes Boreal Forest Herbs and Grasses? Transient Dynamics and Stability, Impacts of Climatic Warming, SI 5.5 Summary, Shrubs CHARLES J. KREBS, MARK R. T. DALE, VILIS 0. NAMS, A. R. E. SINCLAIR, & MARKO'DONOGHUE The Shrub Community at Kluane, Species Composition, Pattern Changes and Succession, 93., Secondary Chemicals in Kluane Shrubs, Biomass Dynamics, Methods of Estimation, Impacts of Treatments, Growth Rates of Shrubs, Methods of Estimation, Impacts of Treatments, Losses of Twigs to Browsing and Natural Mortality, Methods of Estimation, Impacts of Treatments, What Limits Primary Production of Shrubs? 110 X Succession in Boreal Forest Shrubs, Impact of Hare and Moose Browsing, Role of Secondary Chemicals, Summary, Trees MARK R. T. DALE, SHAWN FRANCIS, CHARLES J. KREBS, & VILIS O. NAMS Tree Community at Kluane, Tree Abundance on the Study A rea, Tree Growth, White Spruce Cone and Seed Production, Vegetation Mapping, Fire History of the Study Area, Other Forms of Disturbance, Succession in the Boreal Forest, Fertilizer Effects on Trees, Summary, 135 PART II! HERBIVORES 8 Snowshoe Hare Demography KAREN E. HODGES, CHARLES J. KREBS, DAVID S. HIK, CAROL I. STEFAN, ' ELIZABETH A. GILLIS, & CATHY E. DOYLE The Snowshoe Hare Cycle, 142

5 xiv CONTENTS 8.2 Methods, Demographic Parameters, Density and Rates of Change, Sex and Age Structure, Reproduction, Survival Rates, Causes of Death, Immigration and Emigration, Impacts of Experimental Treatments, Impacts on Hare Demography, Causation of the Hare Cycle, 173 &4.j? Efficacy of the Experimental Treatments, Experimental Scale and Methodological Concerns, 174 &J Interactions with Other Species, Conclusions, The Role of Red Squirrels and Arctic Ground Squirrels RUDY BOONSTRA, STAN BOUTIN, ANDREA BYROM, TIM KARELS, ANNE HUBBS, KARI STUART-SMITH, MIKE BLOWER, & SUSAN ANTPOEHLER Natural History, Red Squirrels, Arctic Ground Squirrels, Community Interactions and Factors Affecting Population Dynamics, Methods, Red Squirrels, Arctic Ground Squirrels, Results, Red Squirrels, Arctic Ground Squirrels, Discussion, / /?o/e of Stochastic Events, Treatment Effects, /?o/e of Squirrels in the Boreal Forest Community, Conclusions, Voles and Mice RUDY BOONSTRA, CHARLES J. KREBS, SCOTT GILBERT, & SABINE SCHWEIGER Natural History and Food Web Links, Community Interactions and Factors Affecting Population Dynamics, Methods, Small Mammal Trapping, Data Analysis, Robustness of Data, Impacts of the Manipulations, Northern Red-Backed Vole, Microtus Voles, 224

6 CONTENTS XV 70.5 What Limits Mice and Vole Populations at Kluane? Northern Red-Backed Vole, Microtus Species, Summary, Forest Grouse and Ptarmigan KATHY MARTIN, CATHY DOYLE, SUSAN HANNON, & FRITZ MUELLER The Ecological Role of Forest and Alpine Grouse, Trophic Position, Life History, Habitats, Current Understanding of Population Dynamics, Predicted Responses to Experimental Treatments, Methods, Duration of Grouse Studies, Shakwak Valley Population Trends, Numerical and Reproductive Parameters on Treatment Grids, Data Robustness and Limitations, Demography of Grouse, Population Trends in the Shakwak Valley, Reproductive Parameters, Population Trends on Control Plots, Relationship of Changes to the Snowshoe Hare Cycle, Response of Forest Grouse to Experimental Treatments, Fertilizer Addition, Food Addition, Predator Exclosure, Predator Exclosure + Food, Discussion, Hypotheses Related to Grouse Population Trends, Did the Experiments Change the Dynamics for Grouse? Linkages on the Same Trophic Level, Linkages to Other Trophic Levels, Conclusions, Comparison with Other Studies, Unexpected Results, Unanswered Questions, Other Herbivores and Small Predators: Arthropods, Birds, and Mammals JAMES N. M. SMITH & NICHOLAS F. G. FOLKARD Methods, Arthropods, Songbirds and Woodpeckers, Other Herbivores, Predicted Responses to Experimental Treatments, Responses by Species Groups, J.7 Arthropods, 264

7 xvi CONTENTS Birds, Other Herbivores, Discussion, Links to the 10-Year Cycle, Effects of Fertilization, Other Patterns in the Food Web, Summary, 270 PART IV MAMMALIAN PREDATORS 13 Coyotes and Lynx MARK O'DONOGHUE, STAN BOUTIN, DENNIS L. MURRAY, CHARLES J. KREBS, ELIZABETH J. HOFER, URS BREITENMOSER, CHRISTINE BREITENMOSER-WUERSTEN, GUSTAVO ZULETA, CATHY DOYLE, & VILIS O. NAMS Methods, Population Monitoring, Foraging Behavior, Functional Responses, Numerical Responses, Density, Adult Survival, Emigration, Recruitment, Social Organization, Home Ranges, Social Groups, Foraging Behavior, Diets, Scavenging Behavior, Hunting Tactics, Group Hunting, Use of Trails, Habitat Use, Functional Responses, Components of Functional Responses, Prey Switching, Synthesis and Conclusions, Numerical Responses, Functional Responses, Total Impact of Predation by Coyotes and Lynx on Hares, Impact of Predation by Coyotes and Lynx on Alternative Prey, Coexistence of Coyotes and Lynx, The Specialist-Generalist Contrast, Other Mammalian Predators MARK O'DONOGHUE, STAN BOUTIN, ELIZABETH J. HOFER, & RUDY BOONSTRA Methods, 325

8 CONTENTS xvil 74.2 Red Fox, Wolf, Weasel, Wolverine, Marten, Mink and Otter, Synthesis and Conclusions, 332 PARTV AVIAN PREDATORS 15 Great Horned Owls CHRISTOPH ROHNER, FRANK I. DOYLE, & JAMES N. M. SMITH Methods, Population Census, Monitoring Diets, Radio Telemetry, Analysis of Telemetry Data, Statistical Analyses, Demography, Reproduction and Population Productivity, Survival and Emigration, Estimating Numerical Responses, Foraging Behavior, Djer, Prey Preferences, Estimating Functional Responses and Predation Impact, Social Organization, Social Status and Vocal Activity, Stability and Size of Home Ranges, Effect of Territoriality on Spacing of Owls, Territorial Behavior and Limitation of Population Increase, Social Behavior and the Time Lag in the Numerical Response, Responses to Large-Scale Experiments, Space Use in Territories with Experimental Hot Spots of Prey, Predator Movements from Poor Patches to Rich Patches, Discussion, Large Floating Population When Resources Are Abundant, Factors Affecting Functional Responses and Predation Impact, Limitation of Population Growth at Peaks of Cyclic Prey, Time Lag in the Numerical Response of a Predator of Cyclic Prey, Factors Limiting Spatial Aggregation of Predators, Raptors and Scavengers FRANK I. DOYLE & JAMES N. M. SMITH Methods, General Approach, 378

9 xviii CONTENTS Population Surveys: The Intensive Search Area, Reproductive Success, Diets, Data Analysis, Predicted Responses of Raptors and Corvids, Responses by Groups and Individual Species, Large Resident Raptors, Large Migratory Raptors, Small Migratory Raptors, Sma// CHW.S, Corvids, Other Raptors, Intraguild Predation, Discussion, Functional, Numerical, and Reproductive Responses to Hare Densities, Resource Partitioning and Diet Width, Intraguild Predation, Methodology and Limitations, Summary, 401 PART VI COMMUNITY AND ECOSYSTEM ORGANIZATION 17 Testing Hypotheses of Community Organization for the Kluane Ecosystem A. R. E. SINCLAIR, CHARLES J. KREBS, RUDY BOONSTRA, STAN BOUTIN, 6 ROY TURKINGTON Experimental Perturbations of the Boreal Forest, Direct and Indirect Effects, The Experiments, Methods, AW Soil Nitrogen, Vegetation, Plant Secondary Chemicals, Herbivore Biomass, Predator Activity, Direct Effects of Trophic-level Perturbations, Fertilizer Addition, Addition of Hare Food, Predator Exclosure, Predator Exclosure and Food Addition, Hare Exclosure, //are Exclosure Plus Fertilizer, Vegetation Removal, Indirect Effects of Trophic-level Perturbations, Fertilizer Addition, Food Addition, Predator Exclosure, 426

10 CONTENTS xix Food Addition and Predator Exclosure, All Hare Exclosure, All 17.5 Discussion, All Direct Effects, All Indirect Effects, Top-down versus Bottom-up, Productivity and Biomass Responses, Other Indirect Effects, A The Role of Secondary Chemicals, The Dominant Pathways in the Vertebrate Community, A Conclusion, Summary, Vertebrate Community Structure in the Boreal Forest: Modeling the Effects of Trophic Interaction DAVID CHOQUENOT, CHARLES J. KREBS, A. R. E. SINCLAIR, RUDY BOONSTRA, & STAN BOUTIN Trophic Interaction and Species Coexistence, Interaction between Vegetation and Herbivores, Interaction between Herbivores and Predators, Modeling, Interaction between Vegetation and Herbivores, Equilibrium Conditions for Snowshoe Hares and Ground Squirrels, Adding Predation to Models of Interaction between Herbivores and Vegetation, The Effect of Herbivore Cycles on Predators, Discussion, Unresolved Modeling Issues, Mechanisms of Coexistence, Top-down and Bottom-up Influences on Community Structure, Trophic Mass Flow Models of the Kluane Boreal Forest Ecosystem JENNIFER L. RUESINK & KAREN E. HODGES Questions about the Ecosystem Dynamics of the Boreal Forest, Modeling the Kluane System, Methods for Constructing Mass Balance Models, Parameterization of Mass Balance Models, Results from Mass Balance Models, Consumption of Plant Biomass by Herbivores, A1A Phase of Cycle Models, A SeasonalModels, Food Addition and Predator Reduction Models, Partial Food Web Models, Discussion, Do Predator-Prey Dynamics Structure the Boreal Forest Ecosystem? 485

11 XX CONTENTS Potential for Other Ecopath Models, Synthesis and Implications, Summary, Conclusions and Future Directions CHARLES J. KREBS, RUDY BOONSTRA, STAN BOUTIN, & A. R. E. SINCLAIR Primary Findings, Predator Trophic Level, Herbivore Trophic Level, Plant Trophic Level, Secondary Findings, Predator Trophic Level, Herbivore Trophic Level, Plant Trophic Level, Opportunities for Further Work, Unsolved Problems, Future Boreal Forest Research, 499 Appendix 1 How to Use the Enclosed Kluane CD-ROM 503 Appendix 2 Table of Contents for the Kluane CD-ROM 504 Index 505