Investigation of the long-term supply–demand relationships of ecosystem services at multiple scales under SSP–RCP scenarios to promote ecological sustainability in China's largest city cluster.

• Demand simulation of ecosystem services (ES) was refined using a system dynamics model. • Supply-demand bundles were established to identify mismatches in ES supply-demand (ESSD). • Imbalances and mismatches of the ESSD were analyzed at the grid, city, and sub-city cluster scales. • Eight, six, and three regulatory zones were identified via the supply-demand bundles at three scales. • Multi-tier regulatory strategies were proposed to improve ES management. Ensuring ecological sustainability in urbanizing mega-regions like the Yangtze River Middle Reaches (YRMR) city cluster is crucial. Distinct dynamics in ecosystem service supply and demand (ESSD) have emerged due to land use changes, climate shifts, and policy drivers. Addressing potential imbalances and mismatches necessitates strategic ESSD regulation. However, it remains unclear how the future ESSD relationship will evolve under the combined impact of climate change and rapid urbanization. To improve demand simulation, this study examined causal links between socio-economic factors, land use, and ES demands from 2000 to 2018 using a system dynamics model. Six ES supplies and demands were simulated under the SSP-RCP scenarios in 2018–2050. Imbalances and mismatches in ESSD were assessed at grid, city, and sub-city cluster scales. The results showed sizable deficits in crop production (CP) and nature access (NA) services at three scales. A synergistic relationship between CP supply and water yield (WY) demand suggested that increased agricultural production could strain water resources. Growing demand for carbon storage (CS) and WY would worsen ESSD imbalance. To maintain long-term ESSD balance, strict carbon policies, land-use restrictions, cross-scale collaboration are needed. A tiered zoning approach based on supply-demand bundles can enhance ecosystem management in a socio-ecological context. [ABSTRACT FROM AUTHOR]