Enhancing ecological networks through the integration of structural connectivity and habitat suitability: a multi-scenario simulation under divergent governance scales

Rapid urban growth has intensified habitat fragmentation in metropolitan regions, threatening biodiversity and weakening ecosystem services. Ecological network (EN) planning in cities still often relies on landscape structure alone, while species requirements and cross-jurisdictional governance are rarely assessed together. We developed an integrated framework for the Chang-Zhu-Tan Metropolitan Area (CZTMA), China. Structurally connected ecological space was first delineated with MSPA and Conefor. Habitat suitability for 20 representative bird species was then modeled with MaxEnt, and species-level logistic outputs were averaged to build a transparent composite suitability surface. Ecological sources were defined where highly suitable habitat overlapped structurally connected patches. We compared this habitat network with a structure-only network and evaluated six optimization scenarios under provincial and municipal governance scales. The integrated approach identified 48 avian habitat sources concentrated in urban blue-green spaces, riparian zones, and key forest patches. These sources overlapped only 2.32% of the structure-based source area, indicating that structural extent alone overestimates functionally usable habitat. The habitat network also required much longer corridors than the structure-only network, reflecting the fragmented distribution of suitable bird habitat. Among the six governance scenarios, provincial-scale quantity-oriented aggregation (S1-QA) performed best, increasing average node degree, clustering coefficient, and global efficiency while reducing average path length. These topology metrics are interpreted here as indicators of spatial coordination among habitat sources rather than as direct measures of social equity. The results show that EN planning in urban agglomerations should combine structural connectivity with species-specific habitat suitability and should be coordinated across jurisdictions. This framework offers practical support for biodiversity planning in rapidly urbanizing regions and for implementing ecological protection redlines in China.