Study On Landscape Connectivity Optimization Of Urban Parks In Central And Core Areas Of Beijing

With the improvement of productivity and the expansion of scale in the process of urbanization,the natural landscape pattern has undergone tremendous changes,and a large number of green spaces have been squeezed out,resulting in the decline of urban ecological environment quality.The ecological space is constantly divided by urban built-up areas,which leads to the phenomena of habitat patch damage,landscape fragmentation and unstable network structure in cities.How to solve the contradiction between urban construction and ecological environment protection is a challenge for future urban construction.As an important part of urban ecosystem,green space is inseparable from people’s life.Park,as an important part of urban green space system,has complex function of spatial characteristics,and plays important ecological and social benefits in the high-density central city,which not only provides important ecological spaces for improving the living environment,but also provides a good habitat for urban creatures.Research has shown that landscape connectivity is one of the important research contents in landscape ecology,in which the index of functional connectivity can be used to analyze patches without actual structural connection by means of the maximum diffusion distance of species,and this index has been used for many times to solve the landscape fragmentation in urban central areas.Improving functional connectivity can strengthen the interoperability between regional ecosystems and resource flows,ensure the diffusion movement of urban species among various habitat patches,alleviate the problems of habitat disappearance caused by landscape fragmentation,optimize the status of urban network structure,and have important value and significance for the protection and improvement of urban ecological environment.Therefore,this paper chose the high-density urban area-the central area and the core area of Beijing as the study area,and took 102 park patches in the area as the study objects.Firstly,the urban parks were counted and analyzed in this range,and the vector database of Beijing urban parks was established by using Arc GIS platform.This paper analyzed and summarized the number,shape and spatial distribution characteristics of urban parks in Beijing,and analyzed the coupling between urban green space and urban parks in the study area,so as to clarify the basis and practical significance of urban parks as research objects,and found out the problems of urban park network structure.Secondly,according to the principle of target species and the actual situation in Beijing,the distance threshold was determined.The functional connectivity index and network connectivity index of graph theory were used to analyze the overall connectivity level of urban parks,identify the importance of maintaining connectivity and the network structure of park patches,then promoted the research of the relationship between the importance of connectivity and the area and shape of patch.Finally,the stepping stone patch theory was used to optimize the patch connectivity of urban parks,and the optimization scheme and implementation strategy were put forward.The main achievements were as follows:(1)In the central area and core area of Beijing,large-scale urban parks were the main ones,with many small and medium-sized patches interspersed among them.The fragmentation degree of patches in large parks was the smallest,while the fragmentation degree of patches in small parks was large and the number of patches was great.It was coupled with urban green space,it was distributed along the southeast-northwest direction,and included the center of urban park distribution.(2)The park network structure formed a Trident network structure,which forms a ring network inside,showing the core regional gathering,uneven spatial distribution in the edge areas,weak connectivity,and the central area parks were not all connected.(3)Twelve parks,including Tiantan Park,Greenway around the Second Ring Road,Yuyuantan park,Taoranting Park,Beijing Zoo and Yuandadu Ruins Park,were identified as important park patches,which can significantly affect the overall network connectivity level in the central area and the core area.(4)The important value of patch connectivity in parks was positively correlated with patch area,and the finger connectivity of patches was better than that of banded or clumpy patches,and the spatial location also affected the important value of patch connectivity.(5)It was considered that increasing stepping stone patches is the key way to optimize the urban network.By adding seven stepping stone park patches,the park patches in the whole study area formed a complete network structure,and the optimized park patch structure landscape has been significantly improved compared with the current green space landscape level.The research on landscape connectivity of urban parks can provide practical reference for future planning of urban green space system,evaluation of park ecological suitability grade,park planning and layout,etc.The index of functional connectivity to urban green space system planning can be tried to application,put forward specific park planning methods and optimization implementation strategies,build an ecological and biodiversity-friendly urban environment,improve the quality of urban parks and improve the biodiversity within cities.It provided ideas and methods of green space planning for high-density central city under the background of stock planning in the future.