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

Abstract

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.