Integrating regional and telecoupled flows into the assessment of ecosystem service supply–demand risks: A case study of carbon sequestration services

Accurate simulation of ecosystem service (ES) supply–demand risks is essential for informing regional spatial planning and supporting sustainable development goals. However, existing studies have largely overlooked the trans-regional flow of ES, highlighting the need for integrated models that account for ES supply, flow, and demand. Ecosystem carbon sequestration service (ECSS), a key metric in achieving China's “dual carbon goals”, exhibits a complex nonlinear association with population carrying capacity, economic development, and ecological conservation. This study focuses on cities along the Yellow River in Henan Province, modeling ECSS as an omni-directional flow. Using ArcGIS and Python, we quantify regional ECSS flows under multiple scenarios by assessing the difference between supply and demand to obtain the actual supply and spatial match. To incorporate external flows, we construct a supply–demand risk indicator system for ECSS. The results indicate that: 1) ECSS supply–demand mismatches are prominent across the region, with high supply–low demand in the southwest and low supply–high demand in central areas. In a static scenario, the area of the deficit zone increased from 2.30 km2 to 4.28 km2 from 2003 to 2023. 2) Under the internal flow scenario, the area of the deficit zone decreased by 1.09, 0.69, and 0.78 km2 in 2003, 2013 and 2023, respectively. ECSS flow partially mitigates deficits, with areas proximal to supply zones receiving more replenishment. 3) As the spatial extent of ECSS flow increases beyond regional boundaries, the total in-region ECSS decreases, yet the extent of deficit areas is reduced compared with static conditions. Most telecoupled flows of ECSS occurred within a 100 km buffer zone. 4) Low ECSS risk zones are primarily located in the southwest (e.g., Luoyang, Sanmenxia) and in northwestern mountainous areas along the Yellow River, whereas critically endangered zones concentrate in urban centers and eastern developed agricultural areas, accounting for 17.3% of the total area. Zhengzhou, Kaifeng, and Puyang are the three cities with the highest ECSS supply–demand risk due to the expansion of central cities and the absence of effective carbon sink land types. These findings highlight the need for localized, flow-informed regulatory measures to manage ECSS supply–demand risk and promote regional sustainability.