Exploring the trade-offs and synergies among ecosystem services to support ecological management in the Yangtze River Delta Urban Agglomeration.

Understanding the interactions among ecosystem services (ESs) is essential for effective ecological management. However, comprehensive investigations into the scale effects, socio-ecological drivers, and bundles of these interactions remain limited, thereby constraining our ability to apply trade-offs and synergies (TOSs) knowledge in ecological management. This study introduced a framework for exploring TOSs among ESs and tested it in the Yangtze River Delta Urban Agglomeration (YRDUA). First, the Integrated Valuation of Ecosystem Services model was employed to map four typical ESs: carbon sequestration (CS), water yield (WY), soil conservation (SC), and habitat quality (HQ). Second, the Pearson correlation coefficient and the geographically weighted regression model were utilized to analyze the relationships between ESs. The optimal parameters-based geographical detector model was then employed to identify socio-ecological drivers, and the self-organizing map was used to delineate the TOS bundles. Finally, ecological management strategies were formulated at both county and city scales. The results showed that: (1) The four ESs demonstrated spatial clustering at both county and city scales, with stable spatial patterns, although their quantities varied over time. From 2000 to 2020, the total values of CS and HQ declined by 1.19 % and 5.14 %, respectively, while WY and SC increased by 23.97 % and 41.58 %, respectively. (2) All ES pairs presented synergies, though their spatial patterns varied according to changes in spatial scale. The synergistic strengths of CS-WY, WY-SC, and WY-HQ decreased from 2000 to 2020, while those of CS-SC, CS-HQ, and SC-HQ increased. (3) Natural drivers exhibited stronger explanatory power than land use and socio-economic drivers, with precipitation being the most influential driver. Precipitation accounted for 38.89 % of the dominant drivers for ES interactions at the county scale and 44.44 % at the city scale. (4) Four TOS bundles were identified at the county scale and three at the city scale. (5) Knowledge of TOSs aids in ecological management decisions, particularly in zoning and strategic planning. These findings can optimize ecological management to minimize trade-offs and maximize the synergies among ESs in the YRDUA and other similar regions worldwide.