Distribution and influencing factors of soil organic carbon in a revegetated small watershed in the Chinese Loess Plateau

Understanding the spatial distribution and controlling factors of soil organic carbon(SOC) at different scales is essential for an accurate estimation of soil organic carbon stocks. Furthermore, this understanding is vital for evaluating the impact of soil managemen to both soil quality and climate change. Our study were conducted in a Loess revegetated small watershed and the effects of topography, vegetation, soil properties factors on SOC distribution and redistribution at surface and different depths were evaluated, the results were as follows:

(1) The interactions between vegetation type and topography and soil depth significantly impacted SOC(P<0.05) in 0-200cm. The relative contribution of topographic factors to the SOC content exceeded that of vegetation type in entire soi lprofile, which implied that topography was the dominant factor controlling the spatial distribution of SOC in the studied small watershed.

(2) SOC stock in deep soil layer(200–500cm) was 7.62kgm⁻², accounting for 40% of the total carbon, soil factors(including soil clay, soil water content, and soil bulk density) were dominant in deep soil layers(200–500cm), averagely accounting for 44.3%.

(3) Vegetation restoration alleviated the redistribution and spatial heterogeneity of SOC by reducing the migration of soil active organic carbon and soil erosion. thus, our research presented some new insights for SOC evaluating in loess-gully regions with their complicated terrain and short recovery time, but with wide distribution in the Loess Plateau of China.