Assessing synergies and trade-offs among water yield, sediment retention, and carbon storage in Yunnan Province, China.

Understanding the spatiotemporal dynamics and interactions of ecosystem services (ES) is critical for regional ecological governance. Taking Yunnan Province, a key ecological barrier in southwestern China, this study quantified water yield (WY), sediment retention (SR), and carbon storage (CS) from 1980 to 2022 using the InVEST model, analyzed their trade-offs and synergies, identified driving factors, and developed ES functional zoning. Results showed that CS and SR exhibited fluctuating upward trends, while WY declined after an early 1980s peak. High-value zones of all three services concentrated in western alpine valleys and southern border regions. In terms of total service volume, the Southwest International Rivers Basin contributed over 68% of WY and 71% of SR, and forests supplied approximately 80% of CS and 84% of SR. Synergies dominated among services, except for the trade-off relationship between WY and SR. Driving factor analysis revealed that precipitation and land cover jointly explained WY variation (both q = 0.28), land cover showed dominant explanatory power for CS (q = 0.67), and the interaction between precipitation and soil type strongly explained SR variation (q = 0.54). In terms of spatial area, the All-high synergy zone covered 22.5% of the province, while the High CS zone represented the most dominant type (36.3%). These findings provide scientific references for local ecological conservation and sustainable development, while offering a methodological framework for similar studies.