Ecological Network Bottlenecks and Restoration Priorities in the Chengjiang Karst Basin, China

Karst river basins require restoration approaches that identify vulnerable connections while distinguishing ecological constraints from governance implementation conditions. This study developed a sequential Structure–Resistance–Connectivity–Governance (SRCG) framework for the Chengjiang River Basin, Guangxi, China. Ecological sources were identified from vegetation vitality, habitat quality, landscape integrity, and hydrological proximity. Natural landscape resistance and anthropogenic disturbance were integrated to delineate potential source-pair corridors. Bottleneck Intensity combined corridor load, minimum corridor width, and high-resistance overlap, and was integrated with ecological movement resistance to delineate Ecological Restoration Priority Zones (ERPZs). Governance Mismatch Index and Administrative Boundary Proximity Index values were applied only after ERPZ delineation. The analysis identified 28 ecological sources covering 312.4 km2, 76 potential connections, three principal bottleneck clusters, and six ERPZs covering 118.5 km2. The upper basin retained a relatively continuous network; whereas, the middle and lower reaches were increasingly constrained by roads, settlements, quarry disturbance, fragmented cropland, and discontinuous riparian vegetation. ERPZ-A, D, E, and F were resistance-dominated, ERPZ-B was bottleneck-dominated, and ERPZ-C was compound-priority. Governance assessment differentiated four implementation contexts. Overall land-cover accuracy was 0.896, Cohen’s kappa was 0.874, and 14 of 16 field sections were concordant with mapped landscape conditions; sensitivity tests retained the principal sources, bottlenecks, and ERPZ cores. The framework separates ecological restoration urgency from implementation difficulty, while its outputs represent potential structural rather than confirmed functional connectivity.