Rhizosphere (eBook)

Front Cover 1
The Rhizosphere An Ecological Perspective 4
Copyright Page 5
Table of Contents 6
List of contributors 10
Acknowledgements 14
Introduction 16
Chapter 1 Root Interactions with Soil Microbial Communities and Processes 22
1.1 INTRODUCTION 22
1.2 THE COMPOSITION OF RHIZOSPHERE MICROBIAL COMMUNITIES 23
1.3 CHARACTERISTICS OF RHIZOSPHERE SOIL THAT IMPACT MICROBIAL COMMUNITY COMPOSITION 34
1.4 IMPORTANCE OF RHIZOSPHERE MICROBIAL COMMUNITIES AT LARGER SCALES 38
1.5 CLOSING OBSERVATIONS 45
ACKNOWLEDGEMENTS 45
REFERENCES 46
Chapter 2 Carbon Fluxes in the Rhizosphere 52
2.1 INTRODUCTION 52
2.2 QUANTITY AND QUALITY OF RHIZODEPOSITS 54
2.3 RHIZOSPHERE CARBON FLUXES UNDER ELEVATED CO2 57
2.4 FUNCTIONAL CONSIDERATIONS 59
2.5 MICROBIAL ASSIMILATION EFFICIENCY OF RHIZODEPOSITS 61
2.6 TEMPORAL DYNAMICS OF EXUDATION AND RESPIRATION 63
2.7 METHODS FOR STUDYING RHIZOSPHERE CARBON FLUXES 66
2.8 PROSPECTS FOR FUTURE RESEARCH 69
ACKNOWLEDGEMENTS 72
REFERENCES 73
Chapter 3 Microfaunal Interactions in the Rhizosphere, How Nematodes and Protozoa Link Above- and Belowground Processes 78
3.1 THE PLANT AS A BRIDGE BETWEEN ABOVE- AND BELOWGROUND POPULATIONS AND PROCESSES 78
3.2 RHIZOSPHERE MICROFAUNA – DIRECT EFFECTS ON CARBON AND NITROGEN FLOWS 79
3.3 RHIZOSPHERE MICROFAUNA – INDIRECT EFFECTS ON PLANT GROWTH 81
3.4 RHIZOSPHERE MICROFAUNA – INTERACTIONS WITH MYCORRHIZAL AND OTHER SYMBIONTS 84
3.5 PLANT RESPONSE TO ABOVE- AND BELOWGROUND HERBIVORY 87
3.6 CONCLUSIONS AND DIRECTIONS FOR FUTURE RESEARCH 88
ACKNOWLEDGEMENTS 88
REFERENCES 89
Chapter 4 Mycorrhizas: Symbiotic Mediators of Rhizosphere and Ecosystem Processes 94
4.1 INTRODUCTION 94
4.2 CONVERGENT EVOLUTION OF MYCORRHIZAS 95
4.3 MYCORRHIZAS AS NUTRITIONAL MUTUALISMS 99
4.4 COMMUNITY INTERACTIONS 102
4.5 ECOSYSTEM INTERACTIONS AND BIOGEOGRAPHY 106
4.6 MYCORRHIZAL FUNCTION IN A CHANGING WORLD 109
4.7 DIRECTIONS FOR FUTURE RESEARCH 115
ACKNOWLEDGEMENTS 117
REFERENCES 117
Chapter 5 Soil Rhizosphere Food Webs, Their Stability, and Implications for Soil Processes in Ecosystems 122
5.1 INTRODUCTION 122
5.2 THE STRATEGY UNDERLYING MATHEMATICALLY CAPTURING THE ESSENCE OF RHIZOSPHERE FUNCTION 123
5.3 RESOURCE FLOW IN THE RHIZOSPHERE 124
5.4 DISCUSSION AND CONCLUSIONS 140
ACKNOWLEDGEMENTS 142
REFERENCES 142
Chapter 6 Understanding and Managing the Rhizosphere in Agroecosystems 148
6.1 INTRODUCTION 148
6.2 INTENSIVE AGRICULTURE: DELIBERATE AND INADVERTENT CONSEQUENCES FOR THE RHIZOSPHERE 149
6.3 RHIZOSPHERE PROCESSES AND AGROECOSYSTEM FUNCTION 154
6.4 THE FUTURE OF THE RHIZOSPHERE IN ECOLOGICAL AGRICULTURE 166
CONCLUSIONS 169
REFERENCES 169
Chapter 7 The Contribution of Root – Rhizosphere Interactions to Biogeochemical Cycles in a Changing World 176
7.1 INTRODUCTION 176
7.2 A CONCEPTUAL OVERVIEW OF RHIZOSPHERE PROCESSES IN BIOGEOCHEMICAL CYCLES 178
7.3 EXAMPLES OF ECOSYSTEM FEEDBACK 186
7.4 SUMMARY: CASCADING CONSEQUENCES OF ALTERED PRIMARY PRODUCTIVITY 194
ACKNOWLEDGEMENTS 195
REFERENCES 195
Chapter 8 The Rhizosphere and Soil Formation 200
8.1 INTRODUCTION 200
8.2 A REVIEW OF CONCEPTS 201
8.3 RHIZOSPHERES: WHERE ECOSYSTEMS CONCENTRATE BIOLOGICAL INTERACTIONS WITH SOIL MINERALS 207
8.4 OVERVIEW OF THE RHIZOSPHERE’S WEATHERING ATTACK 217
ACKNOWLEDGEMENTS 219
REFERENCES 219
Index 222
Color Plates 234