Understanding habitat isolation under urban dynamic growth based on ecological networks: Evidence from the Wuhan metropolitan area, China

Understanding habitat isolation and ecological connectivity from the perspective of heterogeneous landscape interactions constitutes a critical scientific foundation for addressing habitat fragmentation under urbanization and achieving a balance between urban growth and ecological conservation. This study developed a novel two-metric framework consisting of the Urban Growth Isolation Index (UGII) and the Ecological Patch Isolation Degree (EPID), integrated with ecological network (EN) analysis, to quantify the spatiotemporal dynamics of habitat isolation under urban expansion. The results revealed that the Wuhan Metropolitan Area (WMA) underwent intense urban land expansion along a “dispersed–coalesced–dispersed” trajectory from 1990 to 2020. As a consequence, disturbances to ecological sources and ecological corridors gradually increased. The connectivity between ecological sources was impeded, and the isolation level of ecological sources continued to rise. Spatially, the degree of isolation exhibited a distinct pattern, being higher in ecological sources near built-up urban areas and lower in densely clustered ecological sources. In addition, divergent characteristics were observed among urban growth patterns (UGPs). Outlying growth contributed the most to habitat isolation, with a steadily increasing share over time. In contrast, edge-expansion and infilling growth showed relatively smaller and gradually declining contributions. These findings provided practical support for ecological conservation and urban planning. Moreover, the proposed assessment framework, which integrated UGPs with EN, offered a methodological foundation for understanding the interactions between spatial patterns and ecological processes.