Research On The Construction Of Ecological Network In Danjiangkou Reservoir Area Based On Landscape Ecological Risk Assessment

Danjiangkou reservoir is the water source of the middle route project of south-to-north water diversion project in China,and danjiangkou reservoir area is also a sensitive area of ecological environment in China.From the launch of the south-to-north water diversion project,to the elevation of the main dam,and then to the official transfer of water in the middle route project,the landscape ecological pattern of the danjiangkou reservoir area has been greatly affected.The ecological risk of the landscape in the reservoir area is the result of multi-source factors,the identification of the ecological risk of the landscape in the reservoir area is the basis of ecological management,and the construction of ecological network is an effective measure to reduce the ecological risk.Taking danjiangkou reservoir area as the research area,the comprehensive landscape ecological risk assessment of danjiangkou reservoir area in 2000,2005,2010 and 2015 was conducted from three perspectives of natural environment,human environment and landscape pattern through spatial principal component analysis.Based on the evaluation results in 2015,the landscape ecological resistance surface was constructed,and then the least cumulative resistance model was used to construct the ecological network,finally realizing the optimization of landscape pattern in the research area.The main conclusions are as follows:(1)By comparing the danjiangkou reservoir area in 2000,2005,2010 and 2015 comprehensive landscape ecological risk classification figure,is between 2000 and 2015,danjiangkou reservoir area comprehensive basic present similar spatial distribution of landscape ecological risk:high landscape ecological risk area is mainly distributed in the northeast of the study area in xixia county,the main landscape types for the forest landscape;The mild landscape ecological risk area is mainly distributed in the middle of the research area,which has a good ecological environment,strong landscape connectivity and low ecological risk.The comprehensive landscape ecological risk in danjiangkou reservoir area is the result of multiple factors balancing each other in space according to certain priorities.The impact of natural environment factors,especially topographic factors,on landscape ecological risk in danjiangkou reservoir area is greater than that of human society factors and landscape pattern factors.(2)The landscape type map of danjiangkou reservoir area in 2015 was analyzed,and the forestland and water area were selected as the foreground data of the research area.Based on the morphological spatial pattern analysis method,the foreground data were analyzed,and the core patches were extracted.According to the area size and importance index of the patches,10 core patches were selected as ecological sources.The 10 ecological sources,accounting for 45.56%of the total area of the study area,basically cover the core reservoir area,but the spatial distribution of the whole study area is uneven.The most important ecological sources are mainly distributed in the edge of the danjiangkou reservoir area,northeast,west and southwest.The connectivity within the research area is poor,especially there is no ecological source for communication between the northeast and the central part,and there are faults.(3)The 2015 landscape ecological risk assessment results were selected as the resistance surface,and 16 potential ecological corridors between the sources were identified according to the least resistance model.There is a large gap in the length of potential ecological corridors,and the longer corridors are mainly concentrated in the danjiang river basin with poor landscape connectivity in the danjiang estuary reservoir area.The short corridors are abundant and mainly distributed in the west and south of the ecological foci with dense patches.The change of landscape structure of ecological corridor in different widths was analyzed,and it was found that when the width of ecological corridor increased to 1000m,the area proportion of landscape types with high ecological service value,such as forest land and water area,increased,and ecological corridor had higher quality.(4)Based on the principle of hydrological analysis and the potential ecological corridor,14 ecological nodes were identified.The ecological nodes in the study area are relatively evenly distributed and mostly belong to the nodes of cultivated land and forest grass.The area of woodland landscape accounts for more than 30%,which always occupies a dominant position in the ecological nodes.With the increase of the node range,the proportion of ecological elements in the node decreases,while the proportion of rural residents' land and industrial and mining land increases.(5)After the construction of ecological network,the overall connectivity index(?C)and the landscape consistency probability(LCP)of the study area increased by about 25%and 75%respectively,indicating that the construction of ecological network plays a positive role in maintaining the stability of the landscape pattern in danjiangkou reservoir area and can reduce the landscape ecological risks in the reservoir area to some extent.