Grain for Green'' driven land use change and carbon sequestration on the Loess Plateau, China

Land-use change is widely considered to be a major factor affecting soil carbon (C) sequestration (Delta C-s). This paper studied changes to soil C stocks (C-s) following the conversion of farmland to forest, shrub and grassland across the key area for implementing China's Grain for Green'' - the Loess Plateau. The results are based on a synthesis of 44 recent publications (including 424 observations at 70 sites) which has allowed us to further refine our understanding of the mechanisms driving the increase in C-s following farmland conversion. This synthesis suggests that the Delta C-s potential of the Loess Plateau could reach 0.59 Tg yr(-1) based on an estimated annual average Delta C-s rate of 0.29 Mg ha(-1) yr(-1). In the region's different rainfall zones both the main contributing factors and C-s dynamics varied. Across the entire Loess Plateau, C-s showed first an increasing (<5 yr) then a decreasing (6-10 yr) tendency only to increase (>10 yr) yet again. In addition, the Delta Cs rates depended primarily on restoration age. This synthesis demonstrates that both the initial s C-s and the average annual temperature have a significant effect on Delta C-s while the effect of land-use conversion type, rainfall zone, and average annual precipitation were minimal.