Research On The Ecological Security Pattern Of Beijing’s Shallow Mountain Area Based On The Evaluation Of The Supply Side Of Ecosystem Service Flow

With the rapid development of cities,the various types of ecosystem services provided within the city can no longer meet the needs of urban development.When the periphery of the city is shallow mountain area,the difference between the supply and demand of ecosystem services between the city and the surrounding shallow mountain area also increases.The mismatch between the supply and demand area distribution has led to the flow of ecosystem services in space.Various types of ecosystem services flow from areas with potential supply to areas with potential demand,forming an ecosystem service flow.Therefore,due to the good ecological environment and the ability to provide a large number of ecosystem service flows,the shallow mountain area around some cities have become the main supply areas for providing various types of ecosystem service flows to cities,playing an important role in supporting human survival and urban development.Therefore,the ecosystem service flow connects the ecosystem and the social system,where the ecosystem is the supply side of the ecosystem service flow,and the social system is the demand side.The evaluation of the ecosystem service flow from the perspective of the supply side aims to explore whether the various ecosystem services provided by the ecosystem on the supply side meet the needs of the social system for ecosystem services on the demand side.This paper takes the shallow mountain area of Beijing as the supply side of the ecosystem service flow and the plain area where the urban area is located as the demand side of the ecosystem service flow.It evaluates how carbon sequestration services,air pollution reduction services,freshwater supply services and stormwater regulation services provided by shallow mountainous areas meet the demand for such ecosystem services in plain areas.Based on the evaluation results of the supply side of the ecosystem service flow,construct the ecological security pattern of Beijing’s shallow mountain areas,aiming to maintain and improve the ability of Beijing’s shallow mountain areas to provide various ecosystem services through ecological security pattern planning,and to better safeguard human well-being.First of all,this paper selects four evaluation indicators,including the service flow of carbon sequestration and air pollution reduction under the omnidirectional spatial flow type,and the service flow of fresh water supply and rainwater regulation service flow under the directional spatial flow type,and constructs an ecosystem service flow supply-side evaluation process that includes three steps:quantification of the potential supply and demand of the ecosystem service flow,identification of the ecosystem service flow composition area and flow direction drawing,and evaluation standard construction and evaluation element calculation.By comparing the flow of carbon sequestration services,air pollution reduction services,fresh water supply services,and rainwater regulation services provided on the supply side,with the demand for the four ecosystem services on the demand side,it is judged whether the flow provided by the shallow mountain areas meets the needs of the plain areas.The evaluation results show that only all supply areas in the air pollution reduction service flow meet the demand of the plain demand area.In the carbon sequestration service flow,the fresh water supply service flow and the rainwater regulation service flow,the area of the shallow mountain supply area that meets the needs of the plain area accounted for 75.8%,67.2% and 55.5% of each indicator supply area,and the flow provided by the unsatisfied area only accounted for 0.15%-37% of the demand.Secondly,based on the evaluation results of the supply side of the ecosystem service flow,the ecological security pattern of the shallow mountainous area in Beijing was constructed and optimized.In the ecological security pattern of Beijing’s shallow mountain area,the total area of the supply key area,the promotion area and the potential area is 4608.9 km2,accounting for 95.4% of the total area of the shallow mountain area,and the three areas account for 52.8%,31.4% and 11.2% of the total area of the shallow mountain area respectively.There are 14 ecological corridors in four categories,including atmospheric regulation guarantee type,hydrological regulation guarantee type,atmospheric regulation improvement type and hydrological regulation improvement type,with a total length of 323.9km.The optimized ecological security pattern in the shallow mountain area of Beijing has formed a spatial structure of "three districts,four plates,and six corridors",and reasonable implementation strategies are proposed for each part.This study introduces the ecosystem service flow as the basis for constructing the ecological security pattern,evaluates how the service flow provided by the supply side satisfies the demand existing on the demand side,and based on the evaluation results of the supply side of the ecosystem service flow,an ecological security pattern is constructed to improve the ecosystem service capacity of the shallow mountain area to the plain area of Beijing.Therefore,this research not only explores the spatial flow of ecosystem service flows in certain areas between the shallow mountainous areas around some cities and the cities themselves,but the ecological security pattern constructed on this basis will also enhance the supporting role of shallow mountain areas in urban development,and make the shallow mountain areas on the supply side more scientific and reasonable to safeguard human well-being.