“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 (ΔC(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 ΔC(s) potential of the Loess Plateau could reach 0.59 Tg yr(−1) based on an estimated annual average ΔC(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 ΔC(s) 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 ΔC(s) while the effect of land-use conversion type, rainfall zone, and average annual precipitation were minimal.