Decreasing magnitude of soil erosion along vegetation succession on sloping farmland in the Loess Plateau of China: 5 years field monitoring evidence

The impacts of vegetation restoration on the soil erosion have been widely elucidated in the semi-arid regions. However, the magnitude of soil erosion on abandoned sloping farmland still remained unclear and their responses to vegetation succession were rarely addressed. The main objective of this study is to determine the magnitude of soil erosion along vegetation succession and explore the impact of vegetation succession on soil erosion from abandoned sloping farmland. Field observations were employed to monitor the rainfall, runoff, and soil erosion of seven sloping farmland plots with different abandoned ages and bare land from 2015 to 2019. The results indicated that the annual runoff depth and soil erosion modulus of vegetation types were in the range of 0.46 to 5.49 mm·a −1 and 1.3 to 24.5 t·km −2 ·a −1 , respectively. The vegetation effectively reduced the annual surface runoff and soil erosion with reduction of 73.8% to 97.8% and 98.0% to 99.9% as opposed to bare land. However, there were no significant differences in runoff and soil erosion for different vegetation types along succession. The largest event of vegetation types contributed to 38.7%–44.1% of the annual runoff and 42.5%–66.3% of the annual soil erosion, respectively. Vegetation restoration considerably alleviated the contribution of largest erosive event to annual soil erosion. The relationships between soil erosion, runoff and rainfall factors could be fitted well by linear functions, and the performances of regression models in predicting runoff were more satisfactory compared to predicting soil erosion. The Artemisia gmelinii (Agm) + Stipa bungeana (Sb) optimized the trade-off between sediment reduction and runoff maintenance, which should be selected as the suitable vegetation types to achieve the sustainability of socio-ecological systems.