Effects of vegetation types on hillslope runoff and soil erosion on the Loess Plateau

Hillslope runoff and dynamic erosion processes are fundamentally governed by the interaction between vegetation types and environmental conditions. A total of 941 runoff and 1001 soil erosion observations under five vegetation types (grass, tree, shrub, crop, and shrub&grass) were synthesized, and a meta-analysis approach was employed to systematically evaluate the effects of vegetation types and their interactions with environmental factors on hillslope runoff and soil erosion on the Loess Plateau. The results indicated that all vegetation types significantly reduced (p < 0.05) hillslope runoff and soil erosion, with trees demonstrating the most pronounced suppressive effect (p < 0.001). Mean annual precipitation (MAP) was identified as the most influential factor in explaining hillslope runoff, accounting for 61.3 % of the variance, while slope was found to be the dominant factor influencing soil erosion (33.6 %). Threshold analysis revealed that the effectiveness of vegetation in reducing runoff and soil erosion varies significantly under different environmental conditions, such as MAP, topography and soil properties. The most favorable environmental settings for mitigating runoff and soil erosion on hillslopes varied depending on vegetation types. Among them, trees exhibited the most pronounced effect in reducing hillslope runoff under conditions of slope between 10 and 15°, bulk density (BD) of 1.4–1.5 g/cm³, clay content (CC) exceeding 20 %, and soil erodibility factor (K) values ranging from 0.03 to 0.04. With respect to soil erosion, the greatest reduction was observed under slope length (SL) of 2–4 m and CC values ranging from 5 % to 10 %. This study provides quantitative evidence and scientific support for vegetation configuration aimed at ecological restoration and soil and water conservation in the Loess Plateau region.