Wetland requisition-compensation balance based on ecological product value accounting in Yancheng

The wetland requisition-compensation balance policy, an important ecological conservation strategy in China, mandates equivalent-area compensation for development-occupied wetlands to maintain regional wetland inventory. However, widespread functional heterogeneity exists among wetland types. Since China formally institutionalized the concept of ecological products in 2006, scholarly focus has shifted toward quantifying wetland ecological product values encompassing provisioning services, regulating services, and cultural services to comprehensively reflect intrinsic wetland functions. In order to investigate the effects of current wetland requisition-compensation balance policy on ecological profit and loss of regional wetland functions, this study calculated and evaluated the values of wetland ecological product in Yancheng in 2022 based on gross ecosystem product (GEP) accounting model. The results demonstrated that the wetland in Yancheng was classified into 5 types, including coastal wetland , marshy wetland , riverine wetland, lacustrine wetland, and human-made wetland, of which the total area was 5 678.36 km². The total value of wetland ecological product in Yancheng reached 140.094 billion yuan, comprising provisioning services (26.632 billion yuan) , regulating services (107.576 billion yuan) , cultural services (5.886 billion yuan). The mean value of unit-area wetland ecological products averaged 22.30 yuan/(m²·a). In terms of different types of wetland, their values from high to low were: coastal wetland 32.65 yuan/(m²·a), lacustrine wetland 24.57 yuan/(m²·a), riverine wetland 19.97 yuan/(m²·a), human-made wetland 19.22 yuan/(m²·a), and marshy wetland 15.08 yuan/(m²·a). Different wetland types exhibit divergent functional orientations and ecological function values. Coastal wetland provided unique coastal protection 3.66 yuan/(m²·a). As to different types of wetland ecological function, value for flood regulation was highest 14.13 yuan/(m²·a), while value for carbon sequestration was lowest 0.01 yuan/(m²·a). Functional equivalence analysis reveals that uniform ecological value can be achieved when the area ratios of coastal wetland: lacustrine wetland: riverine wetland: human-made wetland reach 1.00 : 1.33 : 1.63 : 1.70 : 2.17. Consequently, it is suggested that when implementing the requisition-compensation balance mechanism across different wetland types, the equivalent value conversion from requisitioned area to ecological compensation can be calculated based on the unit-area wetland ecological product value. This approach can ensure zero net loss of regional ecological product value.