Water erosion control through vegetation restoration: Mechanisms and contributions of vegetation components in Robinia Pseudoacacia forests

Abstract

Soil erosion represents a critical environmental challenge, with vegetation restoration recognized as an effective biological strategy for mitigating water erosion. However, much research has examined how vegetation components regulate water erosion in grassland ecosystems, but these conclusions may not apply to more complex forest ecosystems. This study investigated 42 typical Robinia pseudoacacia forest plots, assessing water erosion characteristics under four scenarios: full vegetation components including grass canopy, litter layer and shallow roots (GLR), retention of litter layer and shallow roots (LR), retention of shallow roots only (R), and no vegetation components (N). These characteristics involved average flow velocity (V), Reynolds number (R_e), Froude number (F_r), Weisbacher-Darcy resistance coefficient (f), sediment concentration (C), soil loss rate (SLR), runoff shear stress (τ), runoff power (W), and critical runoff shear stress (τ_c). Contributions of the grass canopy, the litter layer, and the shallow roots in mitigating water erosion were quantified. The aim of this study is to analyze the influence of each vegetation component separately on soil erosion. The results indicated that the grass canopy significantly increased f and τ_c. The litter layer substantially reduced V, R_e, F_r, C, SLR, and W, while increasing F, τ, and τ_c. The shallow roots significantly reduced V, R_e, F_r, C, and SLR, while increasing τ and τ_c. Litter layer exerted a more pronounced impact than shallow roots and grass canopy, possibly attributed to the substantial litter biomass. Promoting the formation and accumulation of litter layer, along with shallow roots supporting, helps to optimize the soil and water conservation functions of forest ecosystems. These findings enhance understanding of the mechanisms and contributions of vegetation components in controlling water erosion on the Loess Plateau, particularly within complex forest ecosystems.