Identification of Priority Optimization Areas and Determination of Optimal Supply Intervals for Ecosystem Services Based on BBN and PPF-MRT

Urban fringe areas are the core zones where urbanisation conflicts with ecological protection. Current optimisation strategies often overlook the dynamic trade-offs and land-use specificity of ecosystem services (ES). Taking Henan Province as a case study, we first identified urban fringe areas using the Iso Cluster method. We then evaluated four ecosystem services—grain production (GP), carbon storage (CS), soil retention (SR), and water yield (WY)—using the InVEST model. On this basis, (1) We introduced the concept of low-low synergy areas as priority targets for ecological governance. The low-low synergy areas of CS-SR and CS-WY accounted for 28.5% and 26.2% of the total synergy areas, respectively.(2) A Bayesian belief network (BBN) was combined with land-use scenarios to identify optimisation zones for cropland and forest land. For example, in the cropland scenario, priority zones were concentrated in suburban and transitional areas. The CS-SR priority zone covered 1.73% of the total urban fringe area, while the CS-WY priority zone covered 10.23%.(3)The PPF-MRT threshold research method was constructed to overcome the limitations of traditional fixed thresholds, which cannot reflect multi-segment and dynamic changes. For example, in the cropland scenario, CS-WY exhibited multiple synergy intervals, with CS in the ranges of 442.76-451.03 t/ha and CS > 479.17 t/ha.This study presents a systematic framework for "spatial shortfall identification-land-use scenario optimisation-dynamic threshold determination" in ecological governance of urban fringe areas. The framework offers practical guidance for the sustainable management of similar regions worldwide.