Policy-Guided Nationwide Ecological Recovery: Soil Carbon Sequestration Changes Associated With the Grain-to-Green Program in China

Land use change is widely considered as a major factor that affects soil organic carbon (SOC) sequestration. Conversion of sloped croplands to perennial vegetation could increase SOC accumulation. The Grain-to-Green Program (GTGP) implemented in 1999, which converts low-yield sloped croplands into forest, shrub, and grassland, is not only a nationwide ecological recovery project but also the largest payment-for-ecosystem-service program in China. Based on data concerning carbon change in GTGP-related zones collected from published literature, this report (i) provides an estimate of the SOC sequestration potential and the rate of SOC sequestration caused by the GTGP in China; (ii) illustrates the differences in SOC sequestration in zones with different land use types (i.e., forest, shrub, and grassland), different precipitation rates, and restoration ages. Soil organic carbon sequestration caused by the GTGP was estimated to be 14.46 TG C year(-1) (a rate of 0.54 Mg C ha(-1) year(-1)). The SOC sequestration significantly increased in forest lands (P < 0.05), which was greater than 18.7% and 42.9% in shrublands and grasslands, respectively. However, the average rate of SOC accretion was greater in grassland, followed by forest lands. Annual average precipitation and restoration age greatly affected the SOC sequestration. The average SOC sequestration increased with restoration age, whereas the average rates of SOC sequestration decreased. The GTGP resulted in increased SOC storage, making significant contribution to carbon sequestration in China.