[Relationship between Benggang erosion and landscape pattern in the southern red soil zone based on path analysis]

Benggang (collapsing hill) erosion is one of the most serious ecological problems in the south of China. Understanding the relationship between Benggang erosion and landscape pattern is conducive to the study of Benggang occurrence and development from the perspective of landscape ecology, with great significance for Benggang prevention and ecological protection. We classified the Lanxi River Basin in Anxi County, Fujian Province into 32 small watersheds. 16 landscape pattern indices were selected from five aspects, including landscape shape, fragmentation, connectivity, diversity, and quantitative structure. We analyzed the relationship between Benggang erosion and landscape pattern and its mutual influence by dividing the types of landscape in the sub-watersheds. The results showed that the maximum patch index, aggregation index, spreading index, and patch combination index were representative for characterizing the regional landscape pattern. Based on those characteristics, the sub-watersheds in the study area were classified into two categories, i.e. high-disturbance and low-disturbance. In the high-disturbance sub-watersheds, the correlation between Benggang erosion and landscape shape, fragmentation, and connectivity was significant (Moran's I of 0.595, 0.605, and -0.545, respectively), indicating that the more irregular and fragmented the landscape shape, the lower the connectivity between the landscapes, the more prone to Benggang erosion. In the low-disturbance sub-watersheds, the correlation between Benggang erosion and fragmentation, connectivity, and diversity were significant (Moran's I of -0.482, -0.322, and 0.498, respectively), indicating that the higher the degree of aggregation and connectivity between landscapes, and the lower the degree of fragmentation, the less prone to Benggang erosion. For the effect of landscape pattern on Benggang erosion, regardless of high and low-disturbance sub-watersheds, the more complex the landscape shape, the more dispersed and fragmented the distribution was, the more likely it was to promote Benggang erosion. For the effect of Benggang erosion on landscape pattern, the high-disturbance sub-watersheds were more susceptible to the effect of Benggang erosion than the low-disturbance sub-watersheds, which would make the landscape shape more complex, the fragmentation degree increase, and the connectivity degree decrease. Our results can not only provide reference for the prevention and control of erosion, but also provide new ideas for the ecological management of small watersheds in southern China.