Advancing Karst Soil Conservation Evaluation via the Soil Conservation Ratio

ABSTRACT Soil conservation is a key criterion for evaluating ecological restoration processes and governance effectiveness and is of great significance for socioeconomic development and regional sustainability. However, in karst regions, slow soil formation, poor soil fertility, and rapid soil loss lead to a marked deviation between theoretical potential erosion and actual soil loss. Therefore, traditional evaluation methods based on absolute erosion amounts cannot accurately characterize the actual effectiveness of soil and water conservation. In this study, the Revised Universal Soil Loss Equation (RUSLE) model was modified based on the rock exposure rate, and the soil conservation ratio was introduced to evaluate soil conservation effectiveness in the karst trough valley region of southern China from 2000 to 2023. The results showed that the soil erosion modulus in the karst trough valley region exhibited a continuous decreasing trend during the study period, with a change rate of −2.36 t ha −1 yr −1 , whereas the potential soil erosion modulus and soil conservation modulus increased at rates of 10.93 and 13.47 t ha −1 yr −1 , respectively. Compared with that in 2000, the soil conservation ratio increased by 4.83%. In terms of driving mechanisms, the contribution rates of the normalized difference vegetation index (NDVI) and precipitation to the soil conservation ratio were 72.27% and 6.48%, respectively. This study can provide a scientific basis for evaluating soil and water conservation effectiveness and optimizing rocky desertification control in karst.