[Ecosystem Services Assessment and Network Optimization Under Multiple Scenario Simulations in the Karst Area of Southeast Yunnan].

Global climate change and economic growth have altered land use structures， impacting ecosystem services and spatial distributions. The Southeast Yunnan karst region， with its fragile ecological environment and diverse land use types， has become a focal area of research. Utilizing multi-scenario simulations， this study evaluates the impacts of future land use changes on ecosystem services and optimizes the ecological network， aiming to provide scientific guidance for regional ecological protection and sustainable development. Taking the Southeast Yunnan karst regions as the study area， land use data from 2000 to 2020 was analyzed. The Patch-generating Land Use Simulation （PLUS） model was employed to simulate land use patterns under three future scenarios for 2035： SSP126 （sustainable development）， SSP245 （natural growth）， and SSP585 （urban expansion）. The Integrated Valuation of Ecosystem Services and Trade-offs （InVEST） model was used to assess typical regional ecosystem services， and the spatial and temporal dynamics of ecological networks under different scenarios were analyzed. The results indicated that： ① The primary land use types in the Southeast Yunnan karst region were forests， croplands， and grasslands. From 2000 to 2020， the land use transfer area was 6 002.55 km²， with significant transfers among forests， grasslands， and croplands. By 2035， land use changes were projected to exhibit significant differences in intensity and pattern under the different scenarios. ② Compared with 2020， water yield and soil retention were projected to increase by 20 135 under all three scenarios， whereas habitat quality and carbon storage were expected to decline. The SSP126 scenario showed the highest gains in water yield and soil retention， with the least losses in habitat quality and carbon storage compared to those in the SSP245 and SSP585 scenarios. ③ Ecological source areas were mainly concentrated in the eastern and southern regions of Southeast Yunnan， with ecological networks predominantly oriented east-west. By 2035， the area of ecological source regions is expected to increase across all scenarios， enhancing the complexity and connectivity of the ecological network. ④ Future strategies should be based on the "one screen， three belts， and multiple nodes" optimization approach， implementing targeted ecological engineering projects to strengthen east-west corridors and develop north-south corridors. These findings provide scientific recommendations for ecological protection optimization and territorial spatial governance in the karst area of Southeast Yunnan.