Multiscale perspective research on the evolution characteristics of the ecosystem services supply-demand relationship in the chongqing section of the three gorges reservoir area

Grasping the interrelationship between the supply and demand of ecosystem services and the spatial and temporal characteristics of the spatial scale is the foundation of sustainable ecosystem management. This paper uses the Chongqing section of the Three Gorges Reservoir area as the study area, based on the three scales of county, 10-km and 1-km grids; the value equivalent method, quantification of social and economic indicators, and the spatial overlap method are used to measure the supply, demand and supply-demand matching in ecosystem services in the study area during 2000, 2010 and 2018. The results are described as follows: (1) from 2000 to 2018, the ecosystem service supply value (ESSV) at all scales in the study area showed a spatial distribution pattern of "increasing from upstream to downstream" along the Yangtze River. Compared with the county scale, the distribution trend of the ESSV at the grid scale was more complex. (2) from 2000 to 2018, the ecosystem service demand (ESD) at each scale in the study area showed a spatial distribution pattern of "decreasing from upstream to downstream" along the Yangtze River. Compared with the county scale, the global equilibrium distribution at the grid scale was significant. (3) from 2000 to 2018, the supply and demand spatial matching of ecosystem services at all scales in the study area included four types: "high-high", "low-low", "high-low" and "low-high". The phenomenon of supply and demand mismatch in the overall spatial distribution was prominent. Compared with the county scale, the space of grid-scale ecosystem service supply and demand dislocation was shrinking, the spatial areas of high-high and low-low supply and demand were increasing, and the regional supply and demand pattern was more balanced. The coordinated development pattern of ecology and economy was even more remarkable. There are differences and correlations between the supply and demand of ecosystem services at different scales. We propose hierarchical and targeted suggestions and improvement measures for each scale to support the implementation of differentiated regional management, enhance the value of regional ecosystem services, and enrich the scale of ecosystem service supply and demand.