How Ecological Compensation Reshapes Ecosystem Service Trade-Offs and Synergies: A Multi-Scale Analysis of the Miyun Reservoir Basin (2010–2023)

Understanding how ecological compensation policies reshape ecosystem service (ES) interactions is critical for sustainable watershed management. Using the Miyun Reservoir Basin in northern China as a case study, we examined the dynamic changes in land use, provision of ES, and their trade-offs and synergies (TOS) from 2010 to 2023. Four ES—food production (FP), water yield (WY), nutrient retention (nitrogen and phosphorus, NR and PR), and soil retention (SR)—were quantified using the InVEST model. Spearman’s rank correlation was employed to assess TOS at 1 km, 3 km, and township-level administrative units, and geographically weighted regression (GWR) was applied to explore spatial heterogeneity of ES TOS. Results show: (1) Land use change reflected ecological restoration efforts, with cropland decreasing by 1.69% and forest expanding by 2.16%. (2) ES exhibited spatial heterogeneity; regulating services (WY, NR, PR, SR) improved substantially after 2018, while the FP centroid shifted from downstream to upstream areas. (3) Before 2018, FP showed strong trade-offs with regulating services; following intensified policy implementation, these relationships transformed into synergies. (4) Scale effects were evident: grid-scale TOS were stable, while township-level interactions weakened due to administrative aggregation. Overall, ecological compensation reduced ES trade-offs and enhanced synergies, supporting ecological protection in key water source areas while highlighting the need for performance-based policy refinement.