Spatial distribution and influencing factors of urban soil organic carbon stocks in Xi'an City, China

Urban soil organic carbon (SOC) plays an important role in urban ecosystem services. Rapid urbanization and anthropogenic disturbances have created complex and dynamic land-use patterns and heterogeneous urban landscapes, however, the impact of these patterns on the spatial distribution of soil organic carbon density (DSOC) remains unclear. This study investigated SOC using a spatial sampling method from 213 sites in Xi'an City Ring Expressway, China. The results showed that the DSOC ranged from 1.79 to 4.93 kg m(-2), with a mean of 3.31 kg m(-2), and the value of Dsoc was decreased from city center toward suburb with a significant spatial heterogeneity. The DSOC varied with land-use types, being higher in parks, transportation, commercial, and public lands than in industrial, agricultural, parking, and construction lands. The Dsoc was positively related to population density, normalized difference impervious surface index, road density, and landscape shape index, while negatively to aggregation index and patch richness density. Overall, the urbanization of Xi'an City has strongly affected the soil C stocks, and the capacity of urban soils to store C was sustainable. These findings lays a scientific foundation for future soil carbon management in urban development.