Research On The Optimization Of Ecosystem Services From The Perspective Of Urban Green Space Equity

With the continuous migration of rural population to the city,people pay more attention to the value of ecosystem services to the quality of life.With the ever accelerating pace of urbanization,the urban ecological environment is facing greater challenges.The maintenance of urban ecological environment mainly depends on urban green space.As an important guarantee of the ecological needs of urban residents,urban green space can provide many types of ecosystem services for surrounding urban residents,which is of great significance for the maintenance of urban ecological balance.According to the current situation of Xi'an and combined with the specific geographical conditions,the current study selected four ecosystem services:carbon sequestration,biodiversity,improving air quality and alleviating urban heat island effect,by using InVEST model,diversity index model,dry deposition flux model,and land surface temperature inversion and other research methods,and carried out research on the actual urban ecological problems in Xi'an,such as serious haze in winter and hot urban areas in summer.Meanwhile,the research of AcrGIS Addin plug-in based on C#language was carried out on the four services of carbon sequestration,environmental quality improvement,alleviating urban heat island effect and biodiversity,the field survey data is used to verify the study made before,and finally combined with the benefits of ecosystem services provided by green space to guide the planning of Xi'an green space from the perspective of fairness.The main results of the study are as follows:(1)The purpose of current study is to measure and evaluate the ecosystem services of green space,such as biodiversity,improving air quality,carbon sequestration and mitigating urban heat island effect.The distribution range of urban green space diversity index in the main urban area of Xi'an is from 0.694 to 1.725.The complexity of green space community structure is low,and the level of biodiversity could be improved;The highest value of carbon sequestration per unit area in the study area is 12.8 t/hm2.Compared with other regions,the carbon sequestration capacity of Weiyang District,Yanta District and Baqiao District is stronger,and the carbon sequestration capacity of the south is higher than that of the north,and that of the east is higher than that of the west;The dry deposition flux of PM2.5 decreases from north to south,the results show that plants have a certain adsorption capability on PM2.5,the highest daily reduction is 0.0145g/hm3 and the lowest is 0.0058 g/hm3.By extracting the land surface temperature of the green space,it can be seen that the land surface temperature range of the green space area is between 27.1 and 49.8 degrees,which is lower than the average surface temperature of the whole study area,indicating that urban green space can alleviate the urban heat island effect to a certain extent.(2)According to the field survey data,there are great differences in carbon storage distribution among Yanta District,Xincheng District,Beilin District,Baqiao District,Lianhu District and Weiyang District,in which scenic spots and university campuses contribute a large proportion to regional carbon sequestration.The six regional parks make a greater contribution to the regional biodiversity index,while the diversity near residential areas and roads is relatively low.(3)The survey data show that there are obvious differences in the spatial distribution of biodiversity and carbon sequestration among different regional units in the study area,but they have common characteristics.The Gini coefficient value corresponding to the area distribution of urban green space is 0.4752,The Gini coefficient value corresponding to the service of carbon sequestration is 0.4104,the Gini coefficient value of improving air quality,biodiversity and heat island effect are 0.4873,0.2314 and 0.4074 respectively.The results of location entropy classification show that there are obvious differences in the spatial distribution of ecosystem services among different administrative units in the study area.(4)The result of fairness evaluation shows that the ecosystem services of public green space resources in the main urban area of Xi'an generally show a relatively unreasonable distribution.The optimization pattern of green space in Xi'an is analyzed based on location entropy and gini coefficient,the results show that there are differences in ecosystem services to be improved in different regions.According to the differences in services to be improved in different regions,the optimization pattern of each region is analyzed and optimization suggestions are put forward.(5)The plug-ins of four ecosystem service models are developed by using ArcGIS Engine technology.Research and development of AcrGIS Engine plug-in is based on C#language,three modules of biodiversity,carbon sequestration and air purification are developed.The developed plug-in can be embedded in ArcMap to present visual interface operation,and the input data includes vector data,raster data,table and other types of data,and outputs spatial visualization raster data.Plug-in development makes the research and analysis process of ecosystem services of green space in the study area more convenient,and can provide auxiliary reference for the research of others.