The Study On The Construction And Optimization Of Ecological Network Based On MSPA And MCR Models

With the accelerating process of urbanization and the expansion of urban scale,natural resources such as forests and farmland are constantly replaced by buildings and impervious ground.All kinds of landscape patches are isolated and separated from each other,and the ecological service function is constantly reduced.Taking Yanqing District of Beijing as the research object,this paper uses the quantitative analysis software fragstats4.2 to study the landscape pattern and changes of woodland in2008 and 2018 in Yanqing District,and takes the forest resources in 2018 as the prospect analysis data,uses morphological spatial pattern analysis(MSPA)and landscape importance index analysis method to identify ecological source areas,and based on geography Information system software(arcgis10.2)minimum cost distance model(MCR)was used to construct the potential ecological corridor in Yanqing District.The potential corridor network in Yanqing District is graded and its connectivity is evaluated.Based on the evaluation,the optimization is proposed and the spatial connectivity evaluation method is used to compare the network before and after optimization.The main research results are as follows:(1)From 2008 to 2018,the landscape pattern of Yanqing District was more fragmented and unevenly distributed.The density(PD),average fractal dimension(FRAC-MN)and aggregation index(AI)of woodland landscape patches decreased,and the overall dispersion index(IJI)and landscape segmentation index(vision)increased,and the landscape pattern of woodland was broken;the landscape shape index(LSI)increased in the landscape level index,and the degree of disturbance and irregularity of the patches in the study area increased;the spread index(CONTAG)presented The Shannon diversity index(SHDI)decreased,the landscape heterogeneity decreased,and the patch distribution was unbalanced.(2)Through MSPA method and MCR model,a total of 15 ecological source areas and 105 potential corridors were selected,including 19 important corridors and 86 general corridors.However,the spatial distribution of potential ecological corridors in Yanqing District was unbalanced and the connectivity of ecological network was insufficient.The important corridors are mainly distributed in the South and Middle East of Yanqing District,and the typical corridors running through the East and west regions are few in number,which have good connection effect with the surrounding source points,but lack of important woodland corridors in the south to connect ecological nodes;the general corridors are mainly distributed in the northeast of Yanqing District,lack of ecological stepping stones to provide effective connection,and the overall corridor distribution is strong in the East and weak in the West characteristic.Generally speaking,the spatial distribution of ecological corridors in Yanqing District is unbalanced,and the connection degree between them is relatively weak,which needs to be optimized and strengthened(3)After the optimization of the ecological corridor in Yanqing District,the degree of connection was significantly improved.Based on the actual situation of Yanqing District,this paper adds 5 planning corridors,11 stepping stone patches,and optimizes 19 important corridors.The comprehensive index of ecological corridor,α.β.γ index,α index and β index,increased from 0.79,0.66 and 1.9 before optimization to 0.83,0.73 and 2.08.After optimization,the network connection uniformity and connectivity improved.The ecological network presents a multi corridor and multi-point composite network framework.