Identification of ecosystem services supply and demand areas and simulation of ecosystem service flows in Shanghai

In this paper, ecosystem service flow was defined as a dynamic process in which the supply of ecosystem services in a certain region compensates for the demand in other regions with the remaining ecosystem services after meeting its own demand. This process follows the principle of minimum distance. We selected four typical ecosystem services: food supply (supply services), carbon absorption and oxygen release (regulation services), leisure and entertainment (cultural services) and biological habitat preservation (support services). According to the characteristics of the various ecological services, we adopted different methods and indicators to quantitatively evaluate the supply and demand situation and to identify the supply and demand areas of ecosystem services at the level of towns and streets. The Exploratory Spatial Data Analysis Method (ESDA) was used to reveal the spatial clustering models of the supplies and demands of various ecosystem services. A linear programming model was used to simulate the flow direction and flow rate of ecosystem service flow. The results showed the following: (1) All ecosystem services in Shanghai were in short supply and depended heavily on the supply of ecological services outside the city. (2) The supply of various ecosystem services presented the spatial characteristic of "central city-inner suburbs-outer suburbs" corresponding to "low-value clustering-discrete distribution-high-value clustering". (3) The ecosystem services transferred to compensate Shanghai formed flow of the ecosystem service from the outer suburbs to the central urban area, which were dominated by carbon sequestration and oxygen release and the preservation of biological habitats. (4) Within the scope of Shanghai, the priority areas for ecological space conservation, restoration and expansion should be the central city and the inner suburbs, not just the outer suburbs.