Abstract: The maintenance and synergy of ecosystem services within a river basin are fundamental to regional ecological security and high-quality development. Under the context of rapid urbanization, the trade-offs among these services have become increasingly complex. Based on the InVEST model and recreational service index calculations, we quantified the spatiotemporal variations of five types of ecosystem services (water yield, carbon storage, soil conservation, habitat quality, and recreational service) in the Minjiang River Basin from 2010 to 2023. By integrating correlation analysis, hotspot analysis, geographically weighted regression, geographical detector, PLUS model, and the DPSIR model, we analyzed the trade-offs and synergies among these services and elucidated their underlying mechanisms. Through multi-scenario prediction, we further proposed governance paths for optimization. The results showed that ecosystem services exhibited a spatial pattern of “high in the northwest and low in the southeast”. Temporally, carbon storage (generally remaining stable around 145 t·hm^-2), habitat quality (consis-tently above 0.81) and recreational services (fluctuated around 0.76) were generally stable but showed a slight declining trend, while both of water yield and soil conservation showed significant fluctuation.The trade-offs and synergies of ecosystem services exhibited a trend of “strengthened synergy in ecological protection areas and intensified trade-offs in urban expansion zones”.The correlations among services exhibited minimal interannual variation. There was a strong and stable synergy between carbon storage and both habitat quality and recreational service (Spearman correlation coefficient r reaching 0.607-0.786). Water yield showed weak correlations with most other services except for soil conservation (|r| mostly less than 0.3). The geographical detector results identified GDP (with a maximum explanatory capacity q-value of 0.285) and precipitation (with a maximum q-value of 0.400) as the primary driving factors of water yield-habitat quality. The interaction of these two factors with distance to protected areas drove the evolution of the recreational service-habitat quality relationship, while ecological policies had a positive effect on enhancing synergies among services. Scenario simulation revealed that the ecological conservation scenario would promote synergistic enhancement of ecosystem services by 2030, whereas the nature and economic development scenarios would intensify trade-offs and conflicts between ecological and recreational services. This highlighted the importance of proactive ecological regulation for achieving sustainable watershed development. This study would provide a scientific basis for ecological resource allocation and high-quality development in the basin.

Key words: ecosystem service, trade-offs and synergies, driving mechanism, spatial governance, Minjiang River Basin