Soil Carbon Dynamics: An Integrated Methodology

Half-title......Page 3
Title......Page 5
Copyright......Page 6
Contents......Page 7
Contributors......Page 8
Preface......Page 11
1.2 SOIL CARBON RELATIONS: A BASIC CONCEPT......Page 13
1.3.1 Soil chemistry......Page 14
1.3.3 The physiological research line......Page 15
1.3.4 The ecological research line......Page 16
1.4.1 Experimental design of flux measurements and stock taking: limitations at the plot scale......Page 17
1.4.2 Litter and soil organic matter: a meaningful separation and characterization of carbon pools......Page 18
1.4.3 Measuring autotrophic versus heterotrophic fluxes: available methods and their meaning......Page 19
1.4.5 Temperature sensitivity and acclimation: application and shortfalls of different concepts......Page 20
1.4.6 Modelling soil carbon dynamics: current and future model validation and structures......Page 21
REFERENCES......Page 23
2.2 MEASUREMENT PRINCIPLES AND HISTORY OF TECHNICAL DEVELOPMENTS......Page 28
2.3 DISTURBANCES INTRODUCED BY THE MEASUREMENT SYSTEM......Page 33
2.3.1 Vertical pressure gradient......Page 34
2.3.2 Vertical CO2 concentration gradient......Page 35
2.3.4 Other effects......Page 37
2.4 COMPARISON OF THE EXISTING SYSTEMS AND RECOMMENDATIONS......Page 38
2.5 EXPERIMENTAL DESIGN......Page 41
REFERENCES......Page 42
3.1 INTRODUCTION......Page 46
3.2.1 Sources of variability......Page 47
3.2.2.1 Spatial variability......Page 49
3.2.2.2 Temporal variability......Page 50
3.2.3 Laboratory measurements......Page 52
3.2.5 Site variation: random, stratified or systematic design, and avoiding bias......Page 53
3.3 FORMULATING AND TESTING HYPOTHESES......Page 55
3.3.3 Draw the graph......Page 56
3.3.5 Evaluate the data with the appropriate statistical design......Page 57
REFERENCES......Page 58
4.1.1 Soil carbon pools and the global carbon cycle......Page 61
4.1.3 The soil carbon balance......Page 63
4.1.4 Effects of fire in altering the reservoirs of soil carbon......Page 66
4.1.5 Factors determining soil organic carbon turnover......Page 67
4.1.6 Soil organic carbon stocks and climate change......Page 68
4.2.1 The flux approach......Page 69
4.2.2 The repeated inventory approach......Page 70
4.2.3 Examining changes in specific fractions of carbon......Page 71
4.2.4.1 Soil sampling......Page 73
4.2.4.3 Soil carbon analyses......Page 75
4.2.4.4 Bulk density and stone content......Page 77
4.3 CONSIDERATIONS FOR SOIL CARBON MONITORING SCHEMES......Page 78
4.4 UP-SCALING AND THE ROLE OF MODELS FOR DETECTING SOIL ORGANIC CARBON CHANGES......Page 79
4.5 SOIL CARBON STOCK CHANGES: SOME PRACTICAL EXAMPLES......Page 80
4.6 CONCLUSIONS......Page 81
REFERENCES......Page 82
5.2 KNOWLEDGE OF LITTER DECOMPOSITION AND ITS CONTROLLING FACTORS......Page 88
5.3 MEASURING LITTER DECAY......Page 90
5.4 LITTER BAG STUDIES TO QUANTIFY STANDING LITTER TURNOVER TIMES: HOW DO WE DEAL WITH THE ASYMPTOTIC VALUE?......Page 92
5.5 MODELLING LITTER DECAY......Page 93
5.6.2 Incorporation of above-ground litter-derived carbon to SOM......Page 95
5.7 CUTTING-EDGE METHODOLOGIES......Page 96
REFERENCES......Page 97
6.1 INTRODUCTION......Page 103
6.2.1.1 Biological fractionation......Page 104
6.2.1.2 Physical fractionation......Page 105
6.2.1.3 Chemical fractionation......Page 108
6.2.1.4 Black carbon fractionation and quantification......Page 110
6.2.2.1 Compound-specific characterization......Page 111
6.2.2.2 Whole-soil SOM characterization......Page 113
6.3 SHORTCOMINGS......Page 115
6.3.1 The remaining gap between SOM fractionation and characterization......Page 116
6.3.3 Biochemical characteristics of SOM have seldom been directly linked to microbial functioning and resulting SOM dynamics......Page 117
6.4.1 Quantification of the turnover of different SOM fractions by isotope analysis......Page 118
6.4.3 Exploration of new avenues to characterize whole-soil and fraction SOM quality......Page 120
6.5 CONCLUSIONS......Page 122
REFERENCES......Page 123
7.1 INTRODUCTION......Page 139
7.2.1 Eco-physiology of root respiration......Page 140
7.2.2.1 Temperature......Page 141
7.2.2.4 Insolation and carbohydrate supply......Page 143
7.2.2.6 Root morphology and plant age......Page 144
7.2.3.2 Mycorrhizal respiration......Page 145
7.3.1.2 Expressing respiration rates......Page 148
7.3.2.1 Excision methods......Page 149
7.3.2.2 Intact-root chamber methods......Page 150
7.3.2.3 Measurement techniques for respiration of large coarse roots......Page 151
7.3.2.4 Mesh exclusion method......Page 153
7.3.3.1 O2 consumption and CO2 release methods......Page 154
7.3.4 Calculating the Q10......Page 155
7.3.4.1 Fitting curves to measured data......Page 156
7.3.5.1 Set temperature method......Page 157
7.3.5.2 Homeostasis-based methods......Page 158
7.4 MYCORRHIZOSPHERE RESPIRATION AT THE ECOSYSTEM SCALE......Page 159
7.5 CONCLUDING REMARKS......Page 160
REFERENCES......Page 161
8.1 INTRODUCTION......Page 169
8.2 ROOT EXCLUSION: THE TRENCHING APPROACH......Page 170
8.2.2 Limitations and shortcomings......Page 173
8.3.1 Artificial gaps......Page 174
8.4.1 Seasonal variation in partitioning......Page 175
8.4.3 Age effects on partitioning......Page 176
REFERENCES......Page 177
9.1 INTRODUCTION......Page 181
9.2.1 Biomass......Page 182
9.2.2 Ratios of different microbial biomass estimates......Page 183
9.2.3 Basal respiration and metabolic quotients......Page 184
9.2.4 Community oriented approaches......Page 185
9.2.6 Specific substrate use......Page 186
9.2.8 Stable isotope probing......Page 187
9.3 MICROBIAL ACCLIMATION AND STRESS RESPONSE......Page 188
9.3.2 Microbial acclimation to chemical soil properties......Page 189
9.4.2 Modelling......Page 190
9.5 CONCLUSIONS......Page 191
REFERENCES......Page 193
10.2.1.1 Animal waste products and soil carbon dynamics......Page 199
10.2.1.2 Herbivore-induced changes in litter chemistry and soil carbon dynamics......Page 200
10.2.1.3 Herbivore-induced changes in roots and soil carbon dynamics......Page 201
10.2.2 Long-term responses to herbivores......Page 202
10.2.3 Impacts of herbivores on food webs......Page 203
10.3 TROPHIC INTERACTIONS IN SOILS AND DECOMPOSITION......Page 204
10.4.1 Trophic interactions and carbon fluxes through soil food webs......Page 207
10.4.2 Biodiversity and ecosystem function......Page 208
10.5 CONCLUSION......Page 209
REFERENCES......Page 211
11.2.1 General modelling approaches......Page 219
11.2.2 Biotic factors......Page 220
11.2.3 Abiotic factors......Page 223
11.3 EXTRACTING THE RESPONSE OF SOIL RESPIRATION TO ENVIRONMENTAL FACTORS......Page 225
11.3.1 Analyzing soil respiration at the laboratory scale......Page 226
11.3.2 Analyzing soil respiration at the plot scale......Page 227
REFERENCES......Page 229
12.2 SOIL ORGANIC MATTER MODELS......Page 233
12.2.3 Food web models......Page 234
12.2.5 Soil organic matter model evaluation......Page 235
12.2.6 Soil organic matter model application......Page 240
12.2.7 Model weaknesses......Page 241
12.3.1 Carbon inputs to the SOM models......Page 242
12.3.2 Water budget models......Page 243
12.3.4 Model SOM pools, exchanges and turnover rates......Page 244
12.3.5 Other model processes......Page 246
12.3.7 Examples of RothC and CENTURY evaluation and application: short term and small scale......Page 247
12.3.9 Examples of RothC and CENTURY evaluation and application: large scale......Page 249
REFERENCES......Page 251
13.1 INTRODUCTION......Page 257
13.2 HOW MUCH COULD AGRICULTURAL SOILS CONTRIBUTE TO COMBATING CLIMATE CHANGE?......Page 258
13.3 THE FUTURE FOR SOIL CARBON SEQUESTRATION......Page 260
13.4 THE ROLE OF SOILS IN THE KYOTO PROTOCOL......Page 261
13.4.1 The AFOLU guidelines......Page 262
13.4.2.1 Field measurements......Page 263
13.4.2.2 Modelling......Page 264
13.4.3 Multiple benefits from greenhouse gas mitigation by agricultural soils......Page 265
13.5 SUMMARY AND CONCLUSIONS......Page 266
REFERENCES......Page 267
14.2 PARTITIONING SOIL RESPIRATION......Page 269
14.3 SOIL ORGANIC MATTER QUALITY......Page 272
14.4 THE ROLE OF BIOTA AND THEIR INTERACTIONS......Page 273
14.5 SOIL CARBON MODELS......Page 274
14.6 TOWARDS MORE INTEGRATED EXPERIMENTAL APPROACHES......Page 275
14.8 GLOBAL DATABASE......Page 276
REFERENCES......Page 277
15.2.1 Initial site survey......Page 284
15.2.2 Chamber design......Page 285
15.2.5 Profiles of soil CO2 concentration......Page 286
15.2.6.1 Minimum requirements......Page 287
15.3 QUALITY ASSESSMENT AND QUALITY CONTROL......Page 289
REFERENCES......Page 290
Index......Page 293