Changes in soil inorganic carbon following vegetation restoration in the cropland on the Loess Plateau in China: A meta-analysis.

Vegetation restoration in the cropland has been widely implemented to protect the ecological environment of the Loess Plateau, China. However, a quantitative and comprehensive understanding of the changes in soil inorganic carbon (SIC) after vegetation restoration is lacking. Based on 637 pieces of data from 35 studies on the Loess Plateau, we performed a meta-analysis to quantify the variations in SIC after vegetation restoration in the cropland and analyze the influences of environment factors on the variations in SIC. Overall, SIC significantly increased by 6.73% after vegetation restoration. The conversions of cropland to broadleaf forestland, coniferous forestland and grassland significantly increased the SIC contents by 3.16, 14.77 and 6.32%, respectively. The response ratio of SIC (RR-SIC) to vegetation restoration was positively related with restoration age, the response ratio of soil organic carbon and the soil pH respectively, but was significantly negatively correlated with mean annual precipitation and mean annual temperature. The results demonstrated that vegetation restoration in cropland has a high potential to SIC sequestration on the Loess Plateau. The relationship of RR-SIC with environmental factors indicated that the production of pedogenic inorganic carbon plays a crucial role in SIC sequestration after vegetation restoration in the cropland on the Loess Plateau. Our findings highlight that SIC is as vital to soil carbon sequestration as soil organic carbon after vegetation restoration, and SIC should not be neglected for assessing carbon sequestration capacity of vegetation restoration on the Loess Plateau.