Ecological Security Pattern Construction Of Lanzhou Based On The Supply And Demand Matching Of Ecosystem Services

With the rapid development of social and economy in China,the intervention of human activities on natural ecosystems is gradually increased,and the function of regional ecosystem services is gradually reduced.However,the demand of people for ecosystem services is increasing.The imbalance and mismatch between supply and demand of ecosystem services are becoming increasingly prominent.Therefore,constructing the regional ecological security pattern based on the characteristics of supply and demand of ecosystem services is of great significance to safeguard regional ecological security and enhance human well-being.However,at present,the study of ecological security pattern from the perspective of supply-demand matching of integrated ecosystem services is seldom involved.Therefore,from the perspective of supply-demand,this paper analyses the matching situation between supply and demand,identifies the problems existing in the matching between supply and demand,and then constructs the pattern of ecological security,and puts forward corresponding optimization strategies to ensure regional ecological security.Lanzhou is located in the transition zone between the Loess Plateau,Inner Mongolia Plateau and the Qinghai-Tibet Plateau,where the climate is dry,vegetation is sparse,the terrain is fragmented,and the ecological environment is fragile.In recent years,the social and economic development of this region is rapid,as a consequence,the contradiction between economic development and ecological protection has become increasingly prominent.The establishment of the ecological security pattern has been proved to be one of the most important ways to ensure regional ecological security,coordinate social and economic development and ecological protection.This paper takes Lanzhou as a case study,calculates the supply amount,demand amount and supply-demand matching of soil conservation,water conservation,carbon sequestration and food supply,and then by identifying the supply-demand mismatch areas,the core production areas and key supply areas of various ecosystem services in the region were identified,and then based on the matching characteristics,the regional ecological security pattern is constructed,so as to provide a scientific reference for ecological protection in Lanzhou.The main conclusions are as follows:?1?Supply and demand of ecosystem services.The average annual soil conservation,water conservation,carbon sequestration and food supply in Lanzhou are24.32 t.hm^-2,124.97 t.km^-2,32.12 t.km^-2 and 3.73 t.hm^-2,respectively.The spatial distribution of various ecosystem services supply in Lanzhou has a high consistency.Soil conservation,water conservation and carbon sequestration are generally decreasing from south to north,and the food supply shows that high in the flat valley plain area,and lower in the Loess Hilly Region with fragmented terrain.The annual average soil conservation demand index,water resource demand,carbon sequestration demand and food demand of Lanzhou City are 13.39,56.67 t.km^-2,1226.97 t.km^-2 and92.02 t.km^-2,respectively.The spatial distribution of ecosystem services demand is significant.The demand for carbon sequestration and food is the largest in main urban of Lanzhou,followed by the urban areas of three counties;the water demand is high in the main urban areas of Lanzhou,and the valley basin areas with more concentrated irrigation agriculture are also high,while the other areas are low.The demand for soil conservation is generally increasing from south to north.?2?Supply-demand matching degrees of ecosystem services.The annual average supply-demand matching degrees of soil conservation,water conservation,carbon sequestration and food in Lanzhou are-0.0064,-0.0479,-0.0944 and-0.0280,respectively,indicating that the overall matching degree of ecosystem services in Lanzhou is low.In terms of spatial distribution,the surplus areas of water resources are mainly located in the southeast and northwest of the city,while the deficit areas are mainly located in the main urban areas and the northern Loess Hilly Region;the surplus areas of soil conservation are mainly located in the southeast and northwest mountain areas of the city,while the deficit areas are mainly located in the northern Loess Hilly Region of the city;the surplus areas of carbon sequestration services are mainly located in the northwest areas,the area where supply is less than demand is mainly located in the main urban area of Lanzhou;the surplus area where food supply exceeds demand is mainly located in the valley basin in the southeastern part of the city,while the area where supply is less than demand is mainly located in the main urban area of Lanzhou and its surrounding areas.?3?Construction and optimization of ecological security pattern.The key ecological conservation areas?ecological sources?are mainly located in the southeastern and western mountainous areas of the city,with a total area of 1108 km²,accounting for 8.40%of the total area.These areas are the core areas of soil and water conservation and carbon sequestration,and mainly serve the main urban areas of Lanzhou,Yuzhong County and Honggu District.The supply of soil and water conservation and carbon sequestration services can be focused on by setting up protected areas and delimiting ecological red lines in the future.The total area of food supply key conservation areas is 2086 km²,accounting for 15.81%of the city's area,mainly distributed in the eastern part of the city.In the future,the key areas of food supply can be protected by delimiting cultivated land red lines and promoting high-standard farmland.The recharge areas are mainly located in the main urban area of Lanzhou City and Lanzhou New District,with a total area of 413 km²,accounting for3.13%of the total area.In the future,these areas should strengthen greening construction,increase vegetation cover to enhance their soil and water conservation and carbon sequestration capacity;the key recharge areas of food supply are mainly located in the main urban area of Lanzhou,with a total area of 387 km²,and more should be established in the future.Perfect food supply channels to ensure food supply;the key construction areas of soil conservation services is 1830 km²,accounting for 13.87%of the total area,mainly located in the central and northern regions,can improve their soil and water conservation capacity by implementing measures such as returning farmland to forests and grasslands and ecological migration.In order to improve the circulation of services in core production areas and recharge areas,the construction of corridors such as forest belts,water systems and roads should be strengthened between the southeastern and western mountainous areas and the main urban areas in order to enhance the scale and efficiency of ecosystem services flow.