Research on the spatiotemporal distribution differences of land resources ecological security in Southwest China

Land ecological security is a core element of ecological civilization construction. The southwest China features a fragile ecological background and prominent human-land conflicts, making the dynamic evaluation of land ecological security in this region of great significance for territorial spatial ecological restoration. Taking the five provinces in southwest China as the research object, this study developed the DPSRM Model by expanding the traditional PSR Model, and selected 22 indicators from five criterion layers including driving force, pressure, state, response and management. The Entropy Weight-TOPSIS Model, grey correlation analysis and GIS were combined to analyze the spatiotemporal evolution characteristics and core influencing factors of land ecological security in this region from 2012 to 2021. The results showed: (1) the comprehensive index of land ecological security in southwest China increased by 148.06% during the study period, showing a phased characteristic of rapid rise followed by slight fluctuations and stability, with the security grade rising to relatively safe while the overall level remained medium-low. (2) The DPSRM subsystems exhibited significant evolutionary differences, with the management and driving force subsystems showing remarkable improvement. Obvious provincial differentiation was observed: Sichuan and Yunnan were the leading regions, Xizang the potential region, and Guizhou and Chongqing the key improvement regions, with the spatial development gap among regions gradually narrowing. (3) The influencing indicators had both common and heterogeneous characteristics across the region.the sewage centralized treatment rate and other indicators were the common core factors, while each province was dominated by differentiated indicators such as urban construction and agricultural production.