Quantifying ecological spillover contributions to mitigate supply–demand spatial mismatch: An integrated ecosystem service flow framework

Rapid urbanization has intensified the spatial mismatch between ecosystem service (ES) supply and demand, posing critical challenges for sustainable regional development. Existing assessments, largely based on static supply–demand patterns, often fail to capture the redistributive role of ecosystem service flows (ESFs) in regulating spatial ecological imbalances. To address this limitation, we propose an integrated ecosystem service flow framework that explicitly simulates ESF pathways, magnitudes, and spillover contributions, thereby linking static mismatch assessment with dynamic flow processes. Using multi-source geospatial datasets and process-based models, we quantified the spillover effects of water yield (WY), food production (FP), and carbon sequestration (CS) across the Urban Agglomeration in the Middle Reaches of the Yangtze River (UA-MRYR). Results show that ESFs substantially alleviated ecological deficits, with compensation rates of 79.68% (FP), 74.79% (WY), and 61.94% (CS). The three ESFs demonstrated distinct flow mechanisms—unidirectional hydrological routing for WY, market-regulated multi-source networks for FP, and diffusion-driven processes for CS. Integrating flow intensity, total volume, and conflict patterns, we developed a multi-dimensional zoning scheme that delineates Key Functional Zones, Scale Advantage Zones, Potential Cultivation Zones, and Efficiency Focal Zones. By translating ESF spillovers into actionable spatial governance tools, this study offers a scalable pathway for correcting ecological imbalances and guiding adaptive ecological planning in rapidly urbanizing regions.