Construction and optimization of watershed-scale ecological network based on complex network method: A case study of Erhai Lake Basin in China

The ecological network construction and optimization are of great significance in ensuring regional ecological security and optimizing the ecological space of the national territory, therefore constructing the ecological spatial network and proposing optimization countermeasures are conducive to enhancing regional ecological stability. However, current research on ecological networks ignores the ecospatial community structure and the topology characteristics of ecological networks, and lacks a systematic optimization framework. The research scope of the ecological network primarily concentrates on urban administrative units, with less emphasis on the geographic scale of watersheds. This approach is not conducive to the comprehensive management of all elements of ecosystems. Therefore, this research took Erhai Lake Basin as an object, adopted Morphological Spatial Pattern Analysis (MSPA) and landscape connectivity to extract ecological sources, simulate corridors and identify the weak points through the model of Minimum Cumulative Resistance (MCR) and gravity model, constructed the ecological network of Erhai Lake Basin, topologized the ecological network by using the Gephi platform. Based on the results of the analysis of complex network indicators, the optimization strategy of increasing edges was proposed. Priority conservation areas were further identified, an ecological security pattern was designed, and an ecological restoration strategy was planned. Results show that 28 ecological sources, 378 potential ecological corridors, 48 important ecological corridors and 86 ecological weak points formed the complex ecological network in Erhai Lake Basin. The network had clear clustering characteristics and instability, with a high degree concentration in the northeast and uneven betweenness centrality, especially higher in the east. Through topology analysis, 12 increased edge nodes were identified, 9 increased edges were simulated, and 26 weak points were added, significantly improving the network robustness. Based on the ecological security pattern, the restoration strategy with strict control around the lake, conservation of barrier belts and management of priority areas were designed. This study implemented increased edge optimization based on complex network analysis to enhance the stability of the network, which provides a theoretical basis for the optimization of the spatial pattern of Erhai Lake Basin, and is a useful exploration of the ecologically fragile watersheds to protect the environment and achieve high-quality sustainable development.