Spatio-temporal Changes Of Ecological Vulnerability In Zhoushan Island And Its Adjacent Islands

Ecological vulnerability is a huge concern for current ecological environment management and ecological civilization construction.Island is also an important object for the development and utilization.Restricted by factors such as narrow area and isolation from the mainland,the stability of island ecosystem is poor and shows a vulnerable natural property.Entering the Holocene,the island ecosystem is affected by human activities and global changes,and the ecological vulnerability became more compliable.In this content,it is a great significance to study the island ecological vulnerability,analyzing the connection between the island ecological vulnerability and human activities,and to discuss the temporal and spatial changes of island ecological vulnerability under the action of multiple driving factors to guide the sustainable development and utilization of the island.Zhoushan is the first prefecture-level city in China to be established on islands,and islands play an irreplaceable role in its economic development.In the 21 st century,by the rapid development of Marine economy in Zhoushan and the rapid improvement of the urbanization level of the islands have brought severe challenges to protect the ecological environment of the islands.It is urgent to evaluate and study the changes of island ecological vulnerability in the stage of the rapid development,which has practical significance for protecting island ecology and exerting ecological advantages in island economy.Taking Zhoushan Island and its adjacent islands as the research object,this paper selected five years(2000,2005,2010,2015 and 2019)to study the change characteristics of regional ecological vulnerability during the 19 years from 2000 to 2019,and analyzed the change characteristics and driving factors of ecological vulnerability of Zhoushan Island and its adjacent islands.Thesis based on RS and GIS technology,spatial principal component analysis was used to construct the evaluation index system of ecological vulnerability,including Vegetation coverage degree,Slope,Topographic relief,Soil moisture,Shannon’s diversity index(SHDI),Contagion index(CONTAG),Landscape division index(DIVISION)and Shannon’s evenness index(SHEI)8 indexes,computing for Zhoushan Island and adjacent islands ecological vulnerability index(Ecological Vulnerability Index,EVI).Through the evaluation and dynamic analysis of the ecological vulnerability of Zhoushan Island and its adjacent islands during the research period,the temporal and spatial characteristics of the ecological vulnerability of Zhoushan Island and its adjacent islands in the past nearly 20 years were revealed.On this basis,the grey relation analysis method was used to analyze the correlation degree between social and economic factors and ecological vulnerability,and the dominant driving factors affecting ecological vulnerability in the study area.The main conclusions of this paper are as follows :(1)From 2000 to 2019,the ecological vulnerability index of Zhoushan Island and its adjacent islands changed within a range of 0.452-0.476.The degree of ecological vulnerability experienced a trend of rising first,then falling,and then stable,which was basically at the lower level of the medium,and the overall state of the regional ecosystem was good.The ecological vulnerability was the lowest in 2000,reached the highest in 2005,and then decreased and stabilized at a low level.(2)From 2000 to 2019,the ecological vulnerability of each grade from large to small was: light vulnerability > moderate vulnerability > severe vulnerability > potential vulnerability > extreme vulnerability.Light and moderate vulnerability were the main types of vulnerability in the study area.(3)From 2000 to 2019,the spatial distribution of ecological vulnerability was basically the same,and the potential and light vulnerability levels were mainly distributed in the mountainous areas of Zhoushan Island,Jintang Island,Zhujiajian Island,Putuo Mountain Island and other islands.The severe and extreme vulnerability levels were mainly distributed in the northern industrial park and the southern urban area of Zhoushan Island,the western seawall of Jintang Island,the western reclamation area of Zhujiajian Island,the central urban area of Changzhi Island,the southern industrial area of Aoshan Island,and the western seawall of Xiaogan Island,all of which belonged to the areas with high intensity of human activities.(4)The social and economic factors with the highest correlation degree with the ecological vulnerability of Zhoushan Island and its adjacent islands was the Resident population,Built-up area and Floor space of buildings under construction,and the correlation degree was 0.939,0.869 and 0.715,respectively.(5)Contagion index,Vegetation coverage degree,Shannon’s evenness index and Landscape division index are the main factors affecting ecological vulnerability of Zhoushan Island and its adjacent islands.Through the above analysis and research,this paper puts forward the corresponding regulation countermeasures for different levels of ecological vulnerability,the formulation of scientific and reasonable urban planning scheme and the improvement of public awareness of ecological environmental protection,so as to provide a scientific basis for Zhoushan city construction and protection of island ecology.