The Impacts Of Expressway On Landscape Pattern And Ecological Risk

In the process of urbanization,the development of expressway has a great influence on the regional economy and ecological environment while strengthening local economy communication.By virtue of powerful spatial analysis and visualization functions of geographic information system(GIS),combined with the latest data of land-use,The study used spatial analysis,statistical analysis and other analysis methods to investigate impacts of expressway networks on landscape pattern and ecological risk in the process of construction and improvement,exploring the landscape ecology effects by expressways generating in the process of the development.The main conclusions are as follows:(1)Above time series,Beijing expressway has experienced four important change stages—"initial establishment","steady development","rapid development" and "slow development",and the differences of expressway mileages in each stage closely correlated to urban development policies and population density.Above the space,due to the effect of terrain,the highway network distributed densely in the center and east of city,sparsely in west and north-west mountains.(2)In study period,the main land-use type of highway surrounding always was cultivated land,forest land and construction land,but the spatial distribution of land-use changed obviously.In this process,the influence scope of the expressway on land-use extended to 6km from 4km.above the space,the land-use changes around expressways which woodland,arable land,construction land transferred each other was the most significant,and with the increasing distance from the expressway,the main land-use types gradually changed into woodland and arable land from arable land and construction.(3)On the different stages of development,the effects of expressways on the surrounding landscape were different.Based on land-use changes,the scope of the highway network impacting on the surrounding landscape was about 6km,in which the mutual conversion of cultivated land and construction land,the mutual conversion of forest land and construction land,and construction land transferring into the water land were the main factors causing the differences of highway landscape index.(4)Overall,the ecological risks of the expressway surrounding in Beijing showed a descending trend,mainly in reducing the risk level.The distribution of ecological risk index was not homogeneity,lowly in the urban center and highly in near suburban and mountains.The high value of risk index highly aggregated in waters patches and the high aggregation area of high value had the transferring trend toward the urban eastern area.The highly aggregated area of low value mainly distributed edge of 10km buffer.The 8km around the expressway was the inflection point for the impacts of expressways on surrounding ecological risk.