Effects of land-use change on soil inorganic carbon: A meta-analysis

Understanding the changes in soil inorganic carbon (SIC) resulting from land-use change is vital for evaluating terrestrial soil C stocks and predicting global change. However, a comprehensive and quantitative understanding of the impacts of land-use change (LUC) on SIC is lacking. We conducted a meta-analysis to assess the effects of land-use change on SIC based on 576 data points obtained from 29 studies. There were limited studies in humid region, thus our findings only provides insight into the response of SIC to land-use change in arid and semiarid regions. Overall, SIC significantly increased by 5.5% after land-use change. However, not all land-use change types experienced an increase in SIC. SIC was enhanced after land-use change from grassland to farmland (land cultivation, + 30.6%), and declined after land-use change from farmland to grassland (grassland restoration, - 14.4%). The changes in SIC after afforestation were influenced by prior land-use. SIC accumulated after the conversion of sand land to forest (afforestation of sand land), but decreased after the conversion of grassland and farmland to forest (afforestation of grassland, farmland). The subsoil accumulated more SIC than the topsoil after the conversion of sand land to forest and grassland to farmland or forest. Changes in SIC were affected by soil pH and mean annual temperature (MAT). Our findings indicate that SIC increased across all studied land-use change types (grassland to farmland, grassland to forest, farmland to grassland, farmland to forest, sand land to forest), while the magnitude and direction of SIC change varied greatly with different land-use change type.