Study On Ecological Network Construction And Accessibility Of Green Space In Pu’er City

With the acceleration of urbanization rate and the improvement of living standard,a large number of urban construction activities are carried out rapidly,the urban landscape pattern is constantly changed in the process,the green space is squeezed out,and the contradiction with the living space and the production space is becoming more and more prominent.In order to deal with these contradictions in urban construction,in2018,our country put forward the concept of park city,which aims to lead the development of the city through the construction of parks,meet the people’s yearning for a better life in the city,build a modern city with a high degree of harmony and unity of people,city,territory and industry,and let the people share the beautiful environment of the city fairly.Based on the concept of park city,this paper focuses on the ecological function and recreation service function of urban green space,studies the urban green space of Pu’er city from two aspects: ecological network construction and accessibility optimization,and discusses the ecological network construction and accessibility optimization strategy of urban green space to ensure urban ecological security and meet the increasing demand of recreational activities of residents.This paper takes the guidostool box、pajek、ENVI and Arc GIS platform as the technical support,first,through the guidostool box software to carry on the morphological spatial pattern analysis(MSPA),identifies the structural landscape elements;calculates the core area energy factor through the ENVI software,extracts the core area with high energy factor as the ecological source;establishes the landscape resistance evaluation system,constructs the landscape resistance surface,extracts the ecological corridor based on the minimum cumulative resistance model(MCR),constructs the Pu’er city green space ecological network.Based on this,the connectivity and complexity of green space ecological network are measured by the network measurement index of graph theory,and the degree and medium of green space ecological network are calculated by using complex network analysis method by pajek software,and the structure of green space ecological network is quantitatively analyzed.At the same time,based on the Arc GIS network analysis function,using the urban road network data of Pu’er city,creating the urban road network data set of Pu’ er city,establishing the accessibility evaluation index of a kind of green space with recreation as its main function.The research methods and results of this paper can provide reference for the construction of green space in park city,and provide basis for the construction of green space ecological network in Pu’er city and the optimization of the accessibility of recreation green space.The main findings are as follows:(1)The present situation of Pu’er city urban green space covers an area of about42% of the planned area.From the point of view of land use type,the green space land type is mainly agricultural and forestry land,park green space and water area,and the proportion of ancillary green space and protected green space is relatively small.The green space is further divided into seven landscape elements with different connectivity through morphological spatial pattern analysis.Through the statistics of patch number of landscape elements,there are 169 core areas,352 islet areas,62 perforation areas,117 edge areas,160 bridge areas,118 loop areas and 717 branch areas.Through the area statistics,the core area accounts for 71.12% of the green space area,the isolated island area accounts for 3.14% of the green space area,and the void area accounts for 2.20%of the green space area.In general,the green space in the study area has the phenomenon of serious islanding,low spatial connectivity and uneven distribution.(2)On the basis of morphological spatial pattern analysis,the ecological source land is identified and the ecological source land grade is divided;the landscape resistance surface is constructed to extract the ecological corridor;and the complex network analysis of green space is carried out.The results show that there are 8 primary ecological source plots,26 secondary ecological source plots,12 primary ecological corridors and 21 secondary ecological corridors.The structure of green space ecological network is relatively simple,showing the basic pattern of "one ring,one vertical and three horizontal ".The α index,β index and γ index of green space ecological network are 0.51,0.97,0.34,respectively,with low closure and poor connectivity.Most of the ecological sources are single-line connections,and the stability of ecological network and the ability to resist risks are low.The green space ecological network is a heterogeneous network,and the ecological source of large degree is inclined to connect with the ecological source of small degree.The primary ecological source plays a pivotal role in energy flow and material exchange in the green space ecological network.The primary ecological corridor has strong control and influence on the green space ecological network.(3)From the point of view of the distribution of recreational green space,the layout of urban recreational green space in Pu’er city is generally reasonable,and the supply meets the needs of residents in general;however,there are still a few residential areas with poor accessibility and a few recreational green spaces with transitional use.The results show that the urban level recreation green space service range is the largest,the regional level is the second,the community level recreation green space service range is the smallest;the recreation green space service coverage has covered most residential areas in the planning area,and there are only a few service blind areas at present.Calculating the accessibility index of residential area to recreational green space,the results show that the distribution of accessibility index is not balanced,the residential area accessibility index in the middle of the planning area is higher,the residential area accessibility index on the edge is lower,and there is still some unbalanced distribution of recreational green space.(4)According to the actual distribution of urban residents and the habit of using recreation green space nearby,the supply of recreation green space and the demand of residents are calculated,and the overall supply level of recreation green space and the service intensity of each recreation green space are evaluated.The results show that the supply of recreation green space meets the needs of residents in general,and the total amount of resources is reasonable,but due to the difference of population distribution,the intensity of recreation green space service is polarized,and there is a situation of transition and less use.Among them,the recreation green space with too large service intensity is mainly distributed in the middle part of the planning area with large population density and more population distribution,and the recreation green space with too small service intensity is mainly distributed in the marginal areas with small population density and less population distribution in the planning area.