Does scale matter? Analysis and measurement of ecosystem service supply and demand status based on ecological unit

The measurement of the supply and demand status of ecosystem services is the foundation for understanding the differences between and within regional ecosystem service systems. Established that ecological units are crucial to the spatial scale, providing theoretical guidance and methodological support for unified natural resources management. In this study, a framework was constructed to analyze the supply and demand status of regional ecosystem services based on supply and demand coordination. Besides, the equilibrium coupling status of ecosystem supply and demand of 15 primary and 353 secondary ecological units of Jiangsu Province from 2000 to 2020 were quantitatively measured. The research results demonstrate that this analytical framework for the connotation of ecosystems' supply and demand status contributes to the clarification of the interaction between land-use patterns, ecological processes, and supply and demand services. From 2000 to 2020, the supply and demand of ecosystem services in Jiangsu province's ecological units have presented apparent spatial heterogeneity. The deficit quantity of ecosystem service supply and demand in the ecological units exhibited a downward trend from 301 to 233, while the equilibrium quantity and surplus quantity increased from 52 to 120. Specifically, the spatial supply and demand pattern tends to develop better, resulting in a gradually narrowed gap. Additionally, the coupling degree of ecosystem service supply and demand in the ecological units were centered on the drainage basin, which gradually expanded to the east. Thus, ecological units with supply-demand running-in and coordinated coupling stages increased progressively from 70.54% to 73.38%, which suggested prominent regional differentiation. Nonetheless, the coupling coordination degree of the ecological units had an overall upward trend, while the imbalance stage decreased from 44.48% to 37,2%; the coordination stage increased from 55.52% to 62.61%, and the relationship between supply and demand shifted from a spatial mismatch to benign and coordinated development. The research results reveal the temporal and spatial dynamics of the supply and demand of ecosystem services in ecological units and regional differences, laying a foundation for ecosystem management and policy formulation to promote regional sustainable development.