Ecosystem Services Flow and Its Coupling Evaluate of Supply and Demand — A Case Study of Yihe River Basin

Ecosystem services flows (ESF) is an important contributor to the delivery, transformation, utilization, and maintenance of ecosystem services (ES). It provides linkages between the provision of ecosystem services and human demands. The landscape area and dynamic changes in Yihe River Basin were explored through ArcGIS, and the regional ecosystem services value evaluation matrix were also developed through the expert experience, based on which supply rate (SR) and supply-demand ratio (SDR) were constructed. The ecological balance and sustainable development of the Yihe River Basin were discussed based on the potential supply of ecosystem services, and variations in actual human demand at different temporal-spatial scales. The state of ecological balance and sustainable development was also identified based on the spatially explicit model. The result shows: (1) the speed of single land use change dynamics of construction land in the Yihe River Basin was the fastest in the past 30 years. The largest variation of comprehensive land use change dynamics was occurred during 1987 ~ 1995, while the smallest was in 1995 ~ 2005; (2) the minimum and maximum values of the overall ecosystem services SR were 0.500 and 0.916 over the Yihe River Basin in the past 30 years, respectively. There is a noticeable spatial differentiation in the balance of supply and demand in the river basin, the upper reaches were in an ecological surplus area, while the middle and lower reaches were in an ecological deficit; (3) the actual ES delivered by the flows to humans account for a large proportion of potential ES in the Yihe River Basin. However, the services flow and the balance of the ecosystem in the Yihe River Basin were decreased during 1987 ~ 2015. Although the ecological deficit area in the basin was increased significantly, the Yihe River Basin was still in a sustainable state in 2015. The climate regulation service produced by the forest was the most essential contributor to the sustainable development of the Yihe River Basin, including the service of local climate regulation and air quality regulation. The results were expected to provide valuable information for ecosystem management and formulate desired ecological compensation policies.