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