Landscape Pattern Analysis And Ecological Security Evaluation Of Zhalong Wetland

The sustainable development of society is influenced by the ecological environment,and the security of the ecological environment is closely related to human society.In recent years,with the development and utilization of wetlands and the rapid development of tourism industry,wetlands have been interfered by both natural and human factors to a certain extent.Grasping the ecological security degree of wetlands can provide early warning for human disturbance and provide basis for scientific management and protection of wetlands.In this paper,Zhalong wetland is taken as the study area,and Landsat remote sensing images in 1981,1990,2000,2010 and 2020 are taken as data sources.Seven landscapes of Zhalong wetland are extracted by supervised classification and unsupervised classification.Finally,these landscapes are combined into four categories:open water,wetland with surface water,wetland without surface water and dry land for research.With the support of GIS technology,based on the analysis of landscape dynamic changes in Zhalong wetland,the ecological security evaluation model was constructed by using the vulnerability index of loss degree and disturbance degree,and the ecological security of Zhalong wetland was quantitatively evaluated.The safety degree of the study area was divided into five levels:high ecological security,high ecological security,medium ecological security,low ecological security and low ecological security.The results show that:From 1981 to 2020,the areas of open water,wetlands with surface water and wetlands without surface water decreased,while the areas of dry land increased.The wetland with surface water decreased the most,with a total decrease of 269.19km~2,a decrease of 34.06%.In the area transfer-out of landscape types,the transferred-out areas are wetland with surface water,wetland without surface water,dry land and open water.In the area transfer of landscape types,the transfer areas from more to less are dry land,wetlands without surface water,wetlands with surface water and open water.On the scale of type and landscape,the index calculation of the landscape in the study area is carried out.The analysis shows that the maximum patch index has a trend of first decreasing and then increasing,and the number of patches has a trend of first increasing and then decreasing,which indicates that the wetland landscape tends to be integrated after being gradually fragmented.Shannon diversity index and Shannon evenness index are decreasing,which indicates that the landscape diversity in the study area is decreasing and the landscape distribution tends to be unbalanced.From the distribution of ecological security from 1981 to 2020,the degree of security in the central part of the study area is far greater than that in the northern and southern parts of the study area.The high ecological security areas are distributed in the center of the study area,surrounded by higher ecological security areas,medium ecological security areas and lower ecological security areas are around the periphery of the study area in turn,and the low ecological security areas are in the outermost part of the study area,scattered among the lower ecological security areas;The areas with high ecological security and high ecological security decreased,while those with low ecological security and low ecological security increased.The overall landscape ecological security degree in the study area showed a downward trend in the past 40years.