[Simulation of Urban Expansion and Spatial Response of Ecosystem Services in the Yangtze River Economic Belt]

Under the dual context of global climate change and rapid urbanization， investigating the multi-scenario urban expansion processes of the Yangtze River Economic Belt and the spatial response of ecosystem services， while revealing the interaction mechanisms， holds significant importance for coordinating economic growth with ecological environmental protection in the region's future urban development. By integrating coupled model intercomparison project phase 6 （CMIP6） climate models with the PLUS model to simulate sustainable development scenarios （SSP1-2.6）， medium emissions with medium intensity development scenarios （SSP2-4.5）， and high emissions with high intensity development scenarios （SSP5-8.5）， we analyze the urban expansion paths of the Yangtze River Economic Belt in 2050 from multiple perspectives. The research analyzes urban expansion characteristics through multi-dimensional indicators including the urban expansion discrepancy index （UEDI）， urban expansion speed index （UESI）， urban expansion intensity index （UEII）， and landscape expansion index （LEI）. The InVEST model is employed to quantify ecosystem services， while the comprehensive ecosystem services index （CESI） is adopted to calculate integrated ecosystem service values. The geographically weighted regression model is used to reveal the spatial response relationship between urban expansion and ecosystem services. The results show that： ① From 2000 to 2020， the urban expansion of the Yangtze River Economic Belt showed a transition from "low-speed equilibrium to high-speed differentiation，" with the "T-shaped" core area spreading in the downstream and the "point-axis" diffusion in the upstream， and the east-west gradient difference was significant. The spatiotemporal differentiation of ecosystem services was obvious， and the comprehensive ecosystem service index （CESI） increased. ② In 2050， the scale of urban expansion in the Yangtze River Economic Belt will gradually enter a steady state， with the best ecosystem service function under SSP1-2.6， and the ecological degradation will be aggravated by SSP5-8.5， especially in the middle and lower reaches of the ecological corridor. ③ There was significant spatial heterogeneity in the impact of urban expansion on the change of ecosystem service functions， with UEDI and UEII leading ecological degradation and the Yangtze River Delta being inhibited by high-intensity development， and the middle and upper reaches were driven by inefficient expansion. The action directions of UESI and LEI diverged with the evolution of scenarios. In the future， the polycentric network development model should be optimized based on the SSP1-2.6 scenario， and the rigid control of the middle and lower reaches of the ecological corridor and the construction of the upstream ecological conservation area should be strengthened. The results of this study can provide a theoretical basis and policy recommendations for the construction of ecological civilization and high-quality urbanization in watershed-scale cities.