Soil Organic Carbon Sequestration Potential, Storage, and Influencing Mechanisms in China

The soil organic carbon sequestration potential (SOCsp) has important implications for the global carbon cycle and responses to climate change. However, there is a dearth of spatial information specifically for China within this field, and our knowledge regarding the factors influencing SOCsp remains somewhat limited. To solve this problem, this study utilized legacy soil data collected in the 1980s (1979-1984s), combined with climatic landscape zoning, and adopted digital soil mapping techniques to produce spatial prediction models of the density of soil carbon sequestration potential for five designated depths. The results showed that the accuracy of the top soil (0-30 cm) model was higher than that of the subsoil (30-100 cm) model. SOCsp was highest in northwestern, northern, and eastern China and lowest in the southeastern Tibetan Plateau and northeastern China. Scale- and location-specific effects of environmental factors on SOCs were observed, with two-factor effects being stronger than those of their one-factor counterparts. Spatial differentiation characteristics of drivers between topsoil and subsoil layers show significant climatic zonal differences. In the topsoil layer, climate and vegetation are the dominant factors in the arid zone, while the semi-arid zone is mainly regulated by vegetation and land use; in the subsoil layer, climate and land use together dominate SOCsp in the arid and semi-arid zones. In this study, we provide data support for the SOCsp pathway for climate change mitigation processes, while emphasizing the importance of in-depth studies on the mechanisms of SOCsp dynamics through its driving mechanisms.