Spatiotemporal evolution and influencing factors of soil erosion sensitivity in the red soil region of Southern China

Establishing a robust evaluation model for the soil erosion sensitivity index (SESI) is a fundamental prerequisite for the scientific assessment of regional soil erosion. Furthermore, understanding its spatiotemporal evolution and underlying driving mechanisms is essential for developing differentiated and refined regional optimization strategies. This study takes Fujian Province—a typical red soil erosion-vulnerable area in southern China—as a case study. Using spatial principal component analysis (SPCA) and geographical detectors, we selected seven factors (slope, relief amplitude, soil type, annual precipitation, normalized difference vegetation index (NDVI), population density, and land use type) to construct an evaluation indicator system for SESI. The spatiotemporal dynamics and influencing factors of SESI in Fujian Province were then analyzed. The results show that: (1) The spatial distribution pattern of SESI levels in Fujian Province remained relatively stable over the study period and exhibited significant spatial autocorrelation, characterized by high–high and low–low clustering. (2) SESI in Fujian Province generally transitioned from improving sensitivity along the southeastern coast to worsening sensitivity in the northwestern inland areas. (3) SESI was primarily controlled by natural background conditions, particularly topography and landform, with secondary influences from human activities. The driving effects of different factors were mainly manifested through interactive effects, with interaction types evolving from weak interaction to strong interaction, and finally to balanced interaction.