Impact of Soil Erosion on the Temporal and Spatial Dynamics of Organic Carbon in the Typical Black Soil Region of Northeast China

[Objective] To investigate the response mechanism of temporal and spatial distribution of soil organic carbon (SOC) loss to soil erosion intensity, in order to provide basic data for the study of soil carbon cycling mechanism under erosion environment, and provide scientific basis for solving the problem of “thinning and thinning” of black soil. [Methods] This study selected 14 cities (districts or counties) such as Bei'an, Keshan, Kedong and Baiquan counties in the typical black soil area of Songnen Plain as the research objects, and employed the RUSLE model in conjunction with the spatial analysis techniques of GIS to explore the characteristics of temporal and spatial variations in soil erosion and SOC loss in the typical black soil region of Northeast China from 2000 to 2019. [Results] Soil erosion intensity in the study area exhibits a high-north and low-south distribution pattern, predominantly characterized by slight erosion. From 2000 to 2019, the proportion of slight erosion area in typical black soil area showed a inapparent upward trend, while the proportion of slight erosion area and above showed a decreasing trend. Notably, 87.91% of the area did not undergo significant changes in the degree of erosion intensity, with only 3.74% of the are experiencing an escalation in erosion severity. SOC loss exhibited significant spatial distribution differences, generally following a high-north and low-south distribution pattern, with an average annual loss intensity of SOC at 4.74 t/(km2·a). From 2010 to 2019, the total SOC loss showed an increasing trend, with the highest loss occurring in Bei'an, accounting for 37.00% of the total loss in the study area. Between 2015 and 2019, the proportion of areas with soil organic carbon loss intensity less than 5 t/(km2·a) has decreased, while the proportion of areas with loss intensity greater than 5 t/(km2·a) has increased, leading to an increase in the annual average loss intensity. In the northern part of the study area, where soil erosion intensity is high, the abundant SOC content resulted in relatively larger total organic carbon loss upon erosion, giving rise to a distinct regional variation in SOC loss totals. [Conclusion] The temporal and spatial characteristics of SOC loss under the action of erosion, indicating that severe soil erosion is an important driving factor of SOC loss on slope.