Optimizing the spatial layout of terrestrial ecosystem monitoring stations in the Guangdong-Hong Kong-Macao Greater Bay Area

Modernizing ecological and environmental governance systems and capacities necessitates a comprehensive, systematic, and adaptive monitoring station network. The Guangdong-Hong Kong-Macao Greater Bay Area (GBA), a highly urbanized region, faces complex ecological challenges, yet its ecosystem monitoring network remains underdeveloped. Therefore, optimizing the deployment design of terrestrial ecosystem monitoring stations (EMSs) in the GBA is essential for cost-effectiveness. This study employs the Remote Sensing Ecological Index (RSEI) to assess the ecological quality of the GBA, integrating Geodetector analysis, geographic similarity law, and a spatial simulated annealing algorithm to optimize the monitoring station layout. Results indicate that: (1) areas with higher ecological quality are primarily located in the GBA's peripheral regions, with a general decline in average RSEI values from 2000 to 2020. Ecological improvements are largely confined to peripheral areas and regions with favorable natural conditions, while high-density urban zones continue to face challenges. (2) A network of 100 EMSs was identified as the optimal layout for the GBA, effectively covering major ecotypes and prefecture-level cities. The decrease in Mean Squared Error (MSE) slows down as more than 100 stations are added, suggesting that further increases in the number of sites will have little effect on improving accuracy. (3) The theoretical EMSs layout primarily encompasses forest, farmland, and urban ecosystems. Compared with the actual layout, the theoretical EMSs layout has a wider coverage of ecosystem types and area coverage. The optimized layouts proposed in this study offer valuable technical guidance for building an ecosystem monitoring network in the GBA and provide a reference for similar efforts in other regions.