Temporal variation in soil erodibility of typical land use types for purple soil of the Three Gorges Reservoir area

As a key variable in soil erosion models, soil erodibility is strongly linked to alterations in vegetation and soil properties driven by land use and climate change. Thus, accurate quantification of the temporal variation among land use types is highly important for optimizing vegetation selection to meet the demand for dynamic changes in soil erosion. This study was aimed at quantifying the temporal variation in soil erodibility among land use types and elucidating the climate-vegetation-soil interaction mechanisms attributed to these variations in the Three Gorges Reservoir area (TGRA). Six typical land use types of slope farmland (SF), broadleaf forestland (BF), coniferous forestland (CF), economic fruit forestland (EF), shrubland (S), and grassland (G) were selected, and a comprehensive soil erodibility index ( CSEI ) derived from eight soil erodibility indicators was applied to assess soil erodibility. The results demonstrated that the temporal variation in CSEI differed among land use types. The CSEI of the SF fluctuated over time, whereas that of the other land use types first decreased but then gradually increased. Overall, compared with the CSEI of SF, the mean CSEIs of EF, G, S, CF, and BF decreased by 4.81%, 18.97%, 37.83%, 51.25%, and 51.59%, respectively. Temporal variation in the CSEI was comprehensively affected by alterations in vegetation characteristics and soil properties driven by vegetation growth and agricultural activities, but their influencing mechanisms varied with land use types. For SF and EF, temporal variation in the CSEI was primarily controlled by agricultural activities, whereas for other land use types, it was governed by vegetation. Nevertheless, compared with the land use types of CF, S, and G, the temporal variation in the CSEI of BF was influenced not only by the indirect effect of vegetation on improving soil structure but also by its direct mechanical stabilization function. These findings advance our understanding of the mechanism through which climate-vegetation-soil interactions influence soil erodibility, and they provide a practical basis for selecting optimal land use types to prevent soil and water loss in the TGRA.