Relative forces of anthropogenic and natural factors on the evolution of "ecological cancer"-rocky desertification under different man-land relationships

Rocky desertification (RD) is a severe phenomenon in karst areas, often referred to as "ecological cancer." However, studies on RD rarely include comparative analysis of different man-land relationship areas. This lack of analysis leads to difficulties in preventing and controlling RD in local areas with complex man-land relationships. To address this issue, we selected two typical karst areas, Guangnan County (with subtropical humid and agricultural peak-valley area) and Yulong County (with temperate semi-arid and ecological tourism alpine-canyon area), as comparative research areas. We analyzed the evolution of RD in these two typical areas and revealed the relative forces of anthropogenic and natural factors on RD at both a single and comprehensive level by using the geographical detector and the coupled principal component-structural equation model. The study found that (1) the RD in Yulong County was more severe than that in Guangnan County. From 2010 to 2020, RD in both counties showed a positive succession trends. The RD has a high degree of spatial fragmentation, and spatial evolution usually occurs in areas where the man-land relationship is complex. (2) In terms of single factor, the RD in the two counties was mainly affected by anthropogenic factors such as control, farming, behavioral disturbance, and social economy, and natural factors such as geology, soil, topography, and surface state. (3) Comprehensive effects show that forces of anthropogenic vs natural factors on formation/evolution of RD are different between Guangnan County (0.36 for anthropogenic factor vs -0.64 for natural factor) and Yulong County (higher with anthropogenic: 0.44 vs natural: 0.89). (4) Differentiated strategies should be adopted due to role played by anthropogenic and natural factors across different man-land relationship areas to explore suitable control measures for RD. The research creates a scientific basis for the control of RD, ecological restoration, and sustainable development in various regions. It can also be utilized as a valuable reference for comparative analysis of similar geographical phenomena.