The relationship between ecosystem service supply and demand in plain areas undergoing urbanization: A case study of China's Baiyangdian Basin.

Urbanization is an inevitable trend associated with social development that occurs preferentially in plain areas. Ecosystem services (ES) refer to the various benefits that human beings obtain from ecosystems. Competing priorities of economic development and ecological protection lead to conflicts in land use under conditions of urbanization, the root cause of which is an imbalance in the ES supply and demand. Whereas existing studies have mainly focused on the decline of ES supply capacities, an exploration of the extent to which the supply and demand of ES are matched and of their changing trends would be instructive and have practical implications. In this study, we examined changes in the temporal and spatial characteristics of the relationship between ES supply and demand in the Baiyangdian Basin in the North China Plain. We found that ES supply and demand were spatially distinctive. ES supply areas were concentrated in the western mountainous region, whereas ES demand areas were predominantly located in the eastern plain area. The main sources of ES surplus in the study area were woodland and grassland in mountainous areas, comprising 12% of the study region. Strict protection on these lands during the period 1980-2015 ensured a consistently high level of ES supply. In recent years, urbanization has been a major driver of increasing ES demand and decreasing ES surplus and is projected to accentuate the trend of declining ES surplus in the future. However, current policies remain focused on the protection of forests and grassland that predominate in mountainous areas, where urban expansion poses a lower threat compared with plain areas. We therefore recommend a policy emphasis on sustainable urban planning to mitigate ES degradation.