Carbon sequestration in temperate grassland ecosystems and the influence of management, climate and elevated CO2

Summary The substantial stocks of carbon sequestered in temperate grassland ecosystems are located largely below ground in roots and soil. Organic C in the soil is located in discrete pools, but the characteristics of these pools are still uncertain. Carbon sequestration can be determined directly by measuring changes in C pools, indirectly by using 13 C as a tracer, or by simulation modelling. All these methods have their limitations, but long‐term estimates rely almost exclusively on modelling. Measured and modelled rates of C sequestration range from 0 to > 8 Mg C ha −1 yr −1 . Management practices, climate and elevated CO 2 strongly influence C sequestration rates and their influence on future C stocks in grassland soils is considered. Currently there is significant potential to increase C sequestration in temperate grassland systems by changes in management, but climate change and increasing CO 2 concentrations in future will also have significant impacts. Global warming may negate any storage stimulated by changed management and elevated CO 2 , although there is increasing evidence that the reverse could be the case. Contents I. Introduction 2 II. Carbon in temperate grasslands 2 III. The process of carbon sequestration in soils 4 IV. Tracking carbon movement 9 V. Models of soil carbon dynamics 10 VI. Management effects on carbon sequestration 11 VII. Climate‐change effects on carbon sequestration 12 VIII. Response to elevated CO 2 13 IX. Conclusions 14 References 14