A study on spatial network construction and ecological governance of the Bohai Rim coastal zone from a land-sea coordination perspective

The scientifically grounded construction of ecological networks constitutes a strategic and evidence-based approach to achieving functional connectivity between terrestrial and marine habitat patches in coastal zones. Such connectivity is indispensable for conserving coastal biodiversity and sustaining regional ecological security. Focusing on the Bohai Rim Economic Zone—a rapidly developing coastal megaregion facing intensifying land–sea interface pressures—this study develops and refines an integrated land–sea ecological network through spatially explicit, process-informed analysis. We employed morphological spatial pattern analysis (MSPA) to enhance the spatial resolution and ecological realism of existing ecological red line delineations. Ecological sources were systematically identified using a multi-criteria assessment integrating habitat quality (derived from land cover, vegetation indices, and ecosystem service capacity), landscape connectivity (quantified via graph-theoretic metrics), and ecological sensitivity (based on geomorphology, hydrology, and conservation priority designations). A land–sea coupled resistance surface was constructed by weighting both natural constraints (e.g., slope, wetland distribution, marine bathymetry) and anthropogenic pressures (e.g., urban imperviousness, port infrastructure density, fishing intensity). Ecological corridors were then modeled using circuit theory (via Circuitscape), which accounts for multiple pathways and directional flow dynamics across heterogeneous landscapes and seascapes. Finally, targeted optimization strategies—including corridor reinforcement, pinch-point mitigation, and cross-boundary governance recommendations—were formulated based on structural and functional vulnerability assessments. Ecological sources were predominantly concentrated within nationally designated ecological function zones and high-sensitivity areas, including the Taihang Mountains, Yanshan Mountain range, Liaodong Hills, and Shuangtaizi River Estuary National Nature Reserve—regions characterized by high habitat integrity and low anthropogenic disturbance. Ecological corridors exhibited three dominant spatial configurations: (1) the inland–coastal Liaoxi Corridor, linking the Songliao Plain to the Bohai Sea; (2) the mountain–plain transition zone between the Taihang Mountains and the North China Plain; and (3) the fluvial–deltaic corridors along the lower Yellow River. Coastal corridors were most pronounced at the estuaries of the Liao River, Yellow River, and Yalu River—key biogeographic gateways where freshwater, sediment, and nutrient fluxes converge. Critically, these corridors consistently aligned parallel to the coastline and demonstrated high current density and low effective resistance, indicating strong potential for ecological flow and species movement. This study reveals a spatially coherent yet structurally vulnerable ecological network in the Bohai Rim, wherein core sources remain relatively intact but connecting corridors are increasingly fragmented by linear infrastructure, port expansion, and intensive aquaculture. The observed corridor alignment with major estuaries and geomorphic gradients underscores their role as natural conduits for biotic and abiotic exchange across the land–sea interface. However, our circuit-theory–based assessment highlights acute pinch points—particularly near Dalian, Tianjin, and the Yellow River Delta—where cumulative human pressures severely constrain ecological flow. These findings advance coastal ecological network science by explicitly coupling terrestrial and marine resistance processes, and provide actionable, spatially explicit guidance for transboundary ecological planning, ecological red line refinement, and integrated land–sea environmental governance.