Urban ecosystem services supply-demand assessment from the perspective of the water-energy-food nexus

To facilitate sustainable urban development, a pressing issue is how to integrate the water-energy-food nexus (WEF-Nexus) into the assessment of supply and demand of urban ecosystem services (UESs). This study proposed a conceptual framework for the supply-demand assessment of UESs from the WEF-Nexus perspective. Taking the city of Suzhou, China, as an example, the relationships between UESs and WEF-Nexus were identified by the correlation and regression analyses based on the total supply of each urban ecosystem service and evaluation value of each subsystem of WEF-Nexus. Then the supply-demand matching of UESs was evaluated by the supply-demand matching degree and z-score standardization. The results indicated that the water and energy subsystems were positively correlated with water yield/soil retention, and negatively correlated with carbon storage/food production. The food subsystem showed significant positive correlations with carbon storage/food production. Three UESs related to WEF-Nexus, carbon storage, soil retention and food production, were always in short supply, while water yield has shifted to oversupply. The supply-demand spatial mismatches of carbon storage/food production became more pronounced, showing a trend of spreading from urban central areas to the periphery. Therefore, this study provides a scientific basis for proposing supply-demand management strategies of UESs from the WEF-Nexus perspective.