Spatiotemporal Dynamics and Multi-Scenario Projections of Habitat Quality in a Karst Cascade-Hydropower Basin: An Integrated InVEST–IntPLUS–OPGD Framework

Southwest China’s karst region has developed a dam- and reservoir-dense pattern in which cascaded hydropower on mainstem rivers coexists with small hydropower on tributaries, forming a foundation for the region’s low-carbon energy supply. Under China’s “dual-carbon” targets and a strengthening ecological civilization agenda, it is urgent to clarify the mechanisms driving habitat quality (HQ) change under compound disturbances from cascaded hydropower, urbanization, and related pressures—especially the nonlinear pathway through which engineering disturbance propagates to ecological responses via land-use restructuring. To address this need, we develop a Cascade disturbance–Land restructuring–Habitat response chain framework and integrate an InVEST–IntPLUS–OPGD modeling approach to capture HQ dynamics in the Wujiang River Basin (1980–2020), attribute the interactive effects of coupled natural–social drivers, and project ecological responses under alternative 2035 scenarios. Results show that: (1) The basin maintained a stable ecological matrix, with forest land and cropland consistently >82.5% and forest cover near 50%, while construction land increased by 972.15 km2 and water bodies by 354.23 km2 (2) Mean HQ stayed high and declined by only 1.42%, with high and medium–high HQ dominating (>65%). HQ degradation is concentrated in urban expansion areas and reservoir shorelines, whereas most mountainous/forested regions remain stable; and (3) HQ spatial differentiation is mainly shaped by the synergy between forest structure and NDVI, while nonlinear urbanization edge effects impose stronger stress than hydropower development itself. Scenario simulations further indicate that a water protection pathway can enhance HQ by building integrated “water–forest” corridors that promote blue–green synergy. Overall, this study supports improved trade-off design between energy supply and ecological protection in vulnerable karst regions.