Quantitatively identify the factors driving loess erodibility variations after ecological restoration

Abstract

AbstractThe soil erodibility factor is the key index to evaluate regional potential erosion degree and predict soil erosion. Therefore, it is very meaningful to explore the response mechanism of soil erodibility to external environmental factors on the Loess Plateau after ecological restoration. In this study, three soil erodibility factors (K‐USLE, K‐shira, and K‐torri), a comprehensive soil erodibility index (CSEI), different vegetation indices, and five topographic parameters (Topo) in two typical watersheds were selected to achieve this goal. The results revealed that vegetation indices (VI), soil properties (SP), and Topo were significantly affected by regional location and land use types. Vegetation restoration can reduce soil erodibility factors, but the reduction capacity of different land use types varies greatly. SP, VI, and Topo can explain more than 70% of variances in soil erodibility. The partial least squares‐structural equation modelling (PLS‐SEM) illustrated that SP had the largest and significant direct impact on soil erodibility (standard path coefficients (SPC) were −0.935 and −0.895, respectively). Vegetation indirectly inhibited the soil erodibility of the two watersheds by improving SP (SPC were 0.228 and 0.437, respectively), while the indirect impact of Topo mainly interferes with soil erodibility by adjusting vegetation type and spatial distribution (SPC were −0.566 and −0.292, respectively). Furthermore, CSEI was significantly affected by land use, and significantly associated with soil texture, soil organic carbon (SOC), mean weight diameter (MWD), normalized green‐red difference index (NGRDI), and vegetative index (VEG) in both watersheds. The soil in the Xinshui River watershed was more vulnerable to erosion than that in the Zhujiachuan watershed. It is of great significance to explore the response mechanism of soil erodibility to multi‐scale factors to understand the impact of external environmental evolution on soil erosion and sediment yield on the Loess Plateau.