Ecological Risk Assessment Of Rural-urban Ecotone Based On Landscape Pattern

Along with the fast development of the urbanization and forced intervention of human interference, all these features have been arising and effected ecological risk in rural-urban ecotone like that acute changing of land use type, intensive with the supply-demand contradiction land,unreasonable ecological position of landscape,weak ecological environment. Landscape is the area which with the high spatial heterogeneity, and space form and structure influence on the function of regional ecological system, in addition, the landscape structure can accurately display the space distribution and feature of ecological risk,enabling to make spatial analysis. Therefore,we can assess regional ecological risk from the view of landscape structure and landscape type. Ecological risk assessment of rural-urban ecotone not only can provide the data support of ecological planning but promote the rational utilization of land in the development of the development of utilization,coming with important practical significance.This paper,taking Daiyue District as an example, regarding the interference of human as risk sources and seven kinds of landscape types as receptors,analyzes the trend of land use/cover change and landscape pattern in rural-urban ecotone from2000to2010by the way of the principles of landscape ecology,GIS technology and Fragstats software,based on the remote sensing images of Landsat in2000,2005and2010. Many landscape indexes were selected to build the ecological risk index.The spatial and temporal variation law ecological risk was mapped by the way of resampling and spatial interpolation based on the ecological risk index by GIS and geostatistics.The results indicat:(1) The percentage of cultivated land, orchard land, forest land,water land,construction land and unused land are42.15%,18.22%,18.28%,3.886%,14.42%and3.05%respectively.The areas of cultivated land, orchard land, water land and unused land decreased while those of residential land and traffic land increased from2000to2010.The trend of land use is that natural landscape shifte to landscape shift.The slewing rate of construction land is the biggest than orthers land used types from2000to2010,while it was comparatively decreased from2005to2010. Land use general index has slightly raised2.73from265.21to267.93in Rural-urban ecotone from2000to2010. The slewing rate of land use general index is greater than zero,and the actuality of land use is still at an development stage. (2) At landscape level, number of patch,patch densiry,landscape shape index,shannon’s diversity index and Shannon’s evenness index are increased, while the largest patch index are declined.It shows that the intensity of human disturbance and fragmentation of landscape increases, spatial distribution tends to be uniform. At class level, the intensity of human disturbance is the largest to cultivated land, and the largest patch index are declined causedd by the fragmentation of large patch; orchard land and water land were under the smaller human disturbance.It shows that Landscape Fragmentation and Landscape Isolation are increased causedd by the fragmentation and disappearence of large patch,while those of water land changed slightly under the smaller human disturbance.(3) Losing degrees of the ecosystem is diverse in different land use types,it was declined on cultivated land and water land,construction land had a blance,while other types showed a rising trend. In the regional ecological risk level, cultivated land has the biggest contribution rate to55%,while construction land has the least contribution rate to5%.The onstruction to ecological risk is,in order, cultivated land,garden land,forest land,water land,unused land and construction land for construction from largest to smallest.It shows that cultivated land occupied and divided have a maximum potential impact on the region ecological environment and the development of social economy in the progress of urbanization in urban and rural area.(4) In time series, ecological risk distribution was the most discreted in2010,while it was the least centralized distribution in2005.The tendency of ecological risk about each ecological risk sample was increasing from2000to2005contra those from2005to2010. In spacial distribution, the moderate ecological risk level covered the biggest area of the study area.It appears a diffusion increase taking forest land as the center.In the area of each ecological risk level,the area of low ecological risk had no obviously change;the area of high ecological risk increased significantly;the area of extremely high ecological risk decreased caused by the reduction of unused land with high ecological vulnerability.