Interactions between the structure of forest-grassland ecological spatial networks and water conservation functions at a national scale

Amid worsening global ecological issues, China’s ecosystems are significantly degrading, with water conservation functions (WCFs) declining, threatening ecological security. Enhancing forest-grassland ecological space governance and WCFs is crucial for ecological civilization. Ecological spatial networks reflect connectivity, and analyzing the relationship between their structure and WCFs reveals intrinsic links. Changes in the topological structure affect the regional water cycle, thereby influencing WCFs. This study constructed forest-grassland ecological spatial networks (FGESNs) using remote sensing (RS) and geographic information system (GIS) and analyzed their topology. WCFs calculated via the water balance equation shows a positive correlation with six topological indicators: degree, weight, unit weight, coreness, PageRank, and betweenness. Key WCF areas are located in the Northeast Forest Belt, Tibetan Plateau, Yunnan-Guizhou Plateau, and southern hills. Ecological corridors in the Northeast Forest Belt and southern hills have high energy transmission efficiency. From 2000 to 2020, 6290 stable ecological source sites were identified, consistent with China’s “Three Regions and Four Belts” strategy. This study analyzes the correlation characteristics of water conservation services and spatial structure in forest and grass ecological space at national scale, improves water conservation services by improving the network structure of ecological space, and has important theoretical significance for promoting the optimization and adjustment of “structure-function” of forest and grass ecological space and promoting sustainable development.