Abstract: The rapid urbanization has posed a serious threat to the ecological security of river basins. Exploring the trade-offs, synergies, driving factors, and ecological management zoning of regional ecosystem services is of great significance for achieving the sustainable utilization of ecosystems in the Yangtze River Basin. We employed the InVEST model to quantitatively assess the spatial patterns of five major ecosystem services (soil conservation, water yield, habitat quality, and carbon sequestration and food supply) from 2000 to 2023, and used the Spearman correlation coefficient to examine the trade-off and synergy relationships among different ecosystem services and their scale effects. We then applied the Geodetector model and random forest method to identify the dominant driving factors, interactive effects and nonlinear response characteristics, while used the K-means clustering method to identify ecosystem service bundles. Based on these analyses, we proposed ecological management zones and their optimization pathways for the Yangtze River Basin. The results showed that carbon sequestration, habitat quality, and soil conservation exhibited a slight declining trend from 2000 to 2023 by 0.5%, 2.0%, and 10.2%, respectively, whereas water yield and food supply increased by 1.0% and 14.6%. The trade-offs and synergies among ecosystem services displayed significant scale effects. As the spatial scale expanded from grid to county and city levels, the weak synergistic relationships gradually strengthened and became dominant, while the trade-off intensity weakened and the spatial distribution became more clustered. The key driving factors of the five ecosystem services varied significantly. There was also a distinct nonlinear response and a threshold effect: vegetation coverage (explanatory power q=0.45) dominated carbon sequestration, population density (q=0.71) mainly affected habitat quality, precipitation determined (q=0.93) water yield, and slope (q=0.60) affected soil conservation, population density (q=0.56) affected food supply. Based on the clustering of ecosystem services, we classified the study area into three ecological management zones, namely ecological protection zones, ecological conservation zones, and provisioning service zones. We proposed differentiated optimization strategies for each zone.

Key words: ecosystem service, trade-off and synergy, scale effect, ecological management zoning, Yangtze River Basin