The Universal Soil Loss Equation model is often used to improve soil resource conservation by monitoring and forecasting soil erosion. This study tested a novel method to determine the cover and management factor (C) of this model by coupling the leaf area index (LAI) and soil basal respiration (SBR) to more accurately estimate a soil erosion map for a typical region with red soil in Hetian, Fujian Province, China. The spatial distribution of the LAI was obtained using the normalized difference vegetation index and was consistent with the LAI observed in the field (R² = 0.66). The spatial distribution of the SBR was obtained using the Carnegie–Ames–Stanford Approach model and verified by soil respiration field observations (R² = 0.51). Correlation analyses and regression models suggested that the LAI and SBR could reasonably reflect the structure of the forest canopy and understory vegetation, respectively. Finally, the C-factor was reconstructed using the proposed forest vegetation structure factor (C_s), which considers the effect of the forest canopy and shrub and litter layers on reducing rainfall erosion. The feasibility of this new method was thoroughly verified using runoff plots (R² = 0.55). The results demonstrated that C_s may help local governments understand the vital role of the structure of the vegetation layer in limiting soil erosion and provide a more accurate large-scale quantification of the C-factor for soil erosion.