Abstract:

To accurately estimate the surface soil organic carbon (SOC) density and carbon storage in Fengning County, and to determine their spatial distribution and influencing factors, this study utilized 283 surface soil samples collected in 2022. Geostatistical methods and ArcGIS technology were employed to analyze the spatial distribution characteristics of surface SOC, and regional overlay analysis was conducted to identify key factors influencing SOC density. The results indicated that: (1) in 2022, the surface SOC density in Fengning County ranged from 1759.26 to 7810.87 t/km², with an average value of 3631.41 t/km², and a total carbon storage of 32.75 Mt; (2) among the townships, Wudaoying Township had the highest average surface SOC density at 5507.58 t/km², while Datanzhen had the largest surface SOC storage at 2.98 Mt; (3) surface SOC density showed an increasing trend with elevation, with higher densities observed in the western region and the northeastern edge of the plateau. Across different land use types, the order of surface SOC density from high to low was: grassland > forest land > tidal flats > dryland > bare land > construction land. In terms of soil types, purple soils and grey-brown soils exhibited significantly higher SOC densities compared to other soil types. The study concluded that surface SOC density was influenced by both natural and anthropogenic factors, and enhancing SOC content required a comprehensive consideration of topography, soil types, and land use practices.

Key words: soil organic carbon density, organic carbon storage, spatial distribution, influencing factors