How does land-use and climate change affect soil organic carbon stocks and processes in temperate grasslands?

Abstract

Climate and land use changes have significant consequences on the global carbon (C) cycle. Changes to the C cycle in soils of temperate grasslands are important to consider because they often comprise regions of human agriculture and they may significantly alter global C cycles for hundreds to thousands of years. Experiments in temperate grasslands around Western Europe, Northern China, and the United States have shown either slight increases in soil organic carbon (SOC) stocks or no net change over the 20th century, possibly due to increased CO2 stimulating plant growth, in turn offsetting increased SOC loss via soil respiration. There is little consensus in the scientific community over what causes these effects. Experiments testing hypothesis on some SOC factors, such as soil microbial communities, have yielded inconclusive or conflicting results. Uncertainties and lack of inclusion of certain SOC dynamics and experimental variables may explain why model simulations show widely varying predictions of future global and regional SOC stocks and dynamics.