Matching Supply and Demand of Ecosystem Services in the Pinglu Canal Economic Zone from the Perspective of the Water–Energy–Food Nexus

Global climate change and rapid socio-economic development have increasingly exacerbated the imbalance between ecosystem service (ES) supply and demand. Taking the Pinglu Canal Economic Zone as a case study and employing a water–energy–food (WEF) nexus perspective, this study selected three key ESs—water yield, carbon sequestration, and food supply. The InVEST model, supply–demand index (SDI), Pearson correlation analysis, and four-quadrant model were integrated to systematically reveal the spatiotemporal patterns, correlation characteristics, and spatial matching of ES supply and demand from 2005 to 2020. Scale effects and appropriate management scales were clarified through municipal, county, and grid scale comparisons, and a comprehensive management zoning scheme was constructed using a “zoning–classification–grading” framework. The results show that water yield and food supply exhibited an overall increasing trend, while carbon sequestration supply remained stable. Demand for all three services showed continuous growth, with a spatial pattern of “high in the central area and low in the surrounding areas”, consistent with population and economic agglomerations. The county scale was the most effective at capturing local supply–demand characteristics. A “zoning–classification–grading” spatial governance system was constructed based on dominant functions, supply–demand status, and control priority. This study can provide a scientific basis for territorial spatial planning and integrated ecosystem management in the Pinglu Canal Economic Zone and similar regions.