4. Discussion
Taking Miyun County in Beijing as an example, ecosystem products’ supply (potential GEP) and use (actual GEP) were calculated. The results show that in 2020, the potential GEP of Miyun County was 254.32 billion yuan, and the actual GEP was 53.28 billion yuan, approximately 21% of the potential GEP. Water retention services had a higher supply capacity among all the ecosystem products, whereas climate regulation services brought more welfare to human beings. Among all types of ecosystems, wetlands had the highest supply capacity for ecosystem products, which reflects the importance of wetland ecosystems in Miyun County, especially reservoirs, in the supply of ecosystem products. Therefore, when formulating policies, local governments should focus on strengthening the protection of the wetland ecological environment and maintaining its advantages. The actual GEP accounted for only 21% of the potential GEP, indicating that the overall intensity of the local use of ecosystem products is relatively low compared with the potential service supply. Therefore, local governments can consider further rational development and utilisation of ecological resources, promote local economic development under a sustainable model, and achieve a ”win-win situation” between the social economy and the ecological environment. The potential GEP in the Miyun area positively correlated with the actual GEP concerning natural ecosystems, which means the greater the supply intensity of ecosystem products, the higher the use intensity. This correlation also suggested that the availability of ecological products was one of the factors promoting their use. Thus, increasing the supply of ecosystem goods through increased investment in protecting and maintaining ecosystems will directly benefit people. This finding was consistent with Aziz’s study (Tariq Aziz, 2023).
The potential GEP depicts the background condition of the ecosystem, whereas the actual GEP reflects the human demand for ecosystem products. In previous assessments of ecosystem products, most did not distinguish between supply and use but only chose one for accounting (European Union 2020, García-Llamas et al. 2018, McDonald 2009, van Jaarsveld et al. 2005). In our study, the supply and use of ecosystem products were distinguished and compared to fully understand the interdependence between the ecosystem and economic society in Miyun County. Simultaneously, value indicators were selected to compare potential and actual GEPs horizontally to understand the overall supply potential of ecosystem products and the relative situation of human use in the study area, providing a reference for decision-making.
This study has some limitations. From the perspective of ecosystem service flow, three components–supply, flow path, and demand–must be considered. Research on the framework of ecosystem products is still in its initial and conceptual stages, and the feedback mechanism between spatial attribute characteristics and location, such as the spatial flow path, flow, and degree of ecosystem product use, is still poorly understood. Although the total value of the supply and use of ecosystem products in Miyun County was calculated in this study, the spatial flow path of ecosystem products has not been determined. Therefore, we could not determine the flow direction of their supply and use and, thus, could not establish their spatial distribution or connection. Future studies could further explore the flow paths and ranges of ecosystem products between regions. Importance should be provided to applied research on ecosystem service flow, exploring the coupled relationship between ecosystems and human welfare, and promoting the continuous improvement of human welfare.