Scenario-based simulation of ecosystem service supply and demand in China's Yangtze River Economic Belt.

Balancing the supply and demand of ecosystem services is essential for achieving regional sustainable development. A key scientific challenge lies in identifying and improving areas with ecosystem service supply-demand ratio (ESR) imbalances across different spatial scales. Aiming to promote the coordinated development of the economy and ecology in China's Yangtze River Economic Belt (YREB), this study employed a simulated annealing algorithm coupled with the FLUS model to simulate five future land use scenarios for the year 2030. Based on the optimal scenario, ESRs for 2030 were calculated and compared with those in 2010 and 2020. Furthermore, self-organizing mapping (SOM) and Bayesian belief networks (BBNs) were applied to propose optimization pathways from macro and micro perspectives, respectively. The main conclusions are as follows: (1) Over the 30-year period, all four types of ecosystem services exhibited notable changes, with supply states increasing by approximately 4 %-6 % for all services except Carbon Sequestration. In terms of carbon sequestration and soil conservation, Jiangsu and Shanghai remained predominantly in a demand state, with proportions exceeding 90 %. (2) From a macro perspective, CLASS1 areas prioritize economic development, with average ESR values of 0.45, 0.25, 0.15, and 0.30, in contrast to CLASS3 areas, which emphasize ecological conservation. (3) From a micro perspective, the achieved areas for Carbon Sequestration services accounted for the largest share (99.20 %), while the pending optimization area for Water Conservation services accounted for the largest share (92.90 %). To achieve economic and ecological synergistic development in the YREB, differentiated and targeted regulatory strategies should be adopted based on the ESR supply-demand characteristics at multiple spatial scales.