Spatiotemporal Dynamics and Optimization Management of Ecosystem Service Flows in the Yangtze River Delta Urban Agglomeration, China

Ecosystem service flow (ESF) provides a new perspective for understanding the spatial transfer of ecosystem services across urban administrative boundaries, which is of significant importance for optimizing the regional ecological resource allocation. Taking the Yangtze River Delta (YRD) urban agglomeration as a case study, this study analyzed the spatiotemporal evolution characteristics of the ecosystem service value (ESV) and ESF in 41 cities of the region from 2000 to 2020, combining the modified equivalence factor method and the breaking-point model. It also revealed the regional division and evolution patterns of per area ESV and per capita GDP based on ESF in the YRD. The results showed that from 2000 to 2020, the overall ESV in the YRD exhibited a declining trend, with a spatial distribution showing higher values in the south and lower values in the north. Forest contributed over 50% of total ESV, while the value of hydrological regulation services consistently held the largest proportion and contributed the most significant growth. The overall decline in ESF was only 0.6%, with more than 70% of the flow occurring within provincial boundaries. Hangzhou, Taizhou (Zhejiang), and Chuzhou had the highest net outflows, while Jinhua, Changzhou, and Taizhou (Jiangsu) led in net inflows. The number of service-providing areas (SPAs) and service beneficiary areas (SBAs) remained relatively stable. Furthermore, a four-quadrant framework based on ESF, per area ESV, and per capita GDP was constructed, showing that the cities in the YRD mainly shifted between Quadrants I, II, and IV, with several cities transitioning from Quadrant III to II. Based on these findings, optimized management strategies for the coordinated economic-ecological development of the YRD are proposed.