Evaluation Of Island City's Ecological Vulnerability Based On GIS And RS

In recent years,with the continuous construction and development of islands,the corresponding ecological problems have gradually obtained more and more attention.Located in the southeast coast of China,Pingtan Island is the fifth largest island in China and the largest island in Fujian Province.Since the establishment of the Pingtan Comprehensive Experimentation Zone in 2010,the large-scale urbanization has posed a severe challenge to the fragile ecology of the island.Therefore,after the analysis of the island ecological vulnerability,a comprehensive experimentation area in Pingtan was established and a number of ecological protection measures were put forward to provide a scientific basis for the orderly development of the Pingtan Comprehensive Experimentation Zone in the next stage,which is of great significance to the ecological construction and ecological protection.This paper was based on the multitemporal remote sensing images.The ecological vulnerability assessment model of islands was constructed by coupling multiple ecological indicators,the analysis of ecological vulnerability and its dynamic changes after the initial construction of the comprehensive experimentation area in Pingtan.It showed the ecological vulnerability change trend of Pingtan experimentation area from 2009 to 2017,and explored the driving factors of the change.On this basis,the landscape pattern was further analyzed,the relationship between ecological vulnerability and land use change was studied and the targeted ecological protection countermeasures was put forward during island city construction.The main research contents and results are presented as follows:(1)Based on the DEM data and remote sensing data,the nine ecological vulnerability indices of the Pingtan Island could be obtained.The weights of indexes were calculated by analytic hierarchy process(AHP),and the ecological vulnerability assessment results of the three research phases in Pingtan Island were obtained by coupling index.According to the results,from 2009 to 2017,the ecological fragility of Pingtan Island showed an upward trend,and its average value increased from 0.406 in 2009 to 0.458 in 2017,with a change rate of 12.81%.This shows that after the establishment of the comprehensive experimentation area in Pingtan,a large area of development and construction exacerbated the ecological fragility of Pingtan Island,as well as weakened its ability to resist the interference of the external environment.(2)The ecological fragility images of the 3 phases were classified,and the results showed that the ecological vulnerability of Pingtan Island in the 3 phases was mainly mild vulnerability,followed by the severe vulnerability and extreme vulnerability.In 2009,2015 and 2017,the proportion of the moderate and above fragile area to the total area is 51.34%,57.54%,62.27%respectively.The ecological vulnerability of Pingtan Island in the 3 phases is in the middle level,and the degree of vulnerability has increased on yearly basis.The difference operation changed the fragile zoology,and the results showed that from 2009 to 2017,ecological vulnerability level increased by 116.69km2,accounting for 41.49%of the total area.The level of total area decreased to 59.34km2,taking up 21.10%of the total area,which indicates that the construction and development of the comprehensive experimental zone has intensified the ecological vulnerability of the island.(3)To further explore the relationship between land use and landscape pattern change in Pingtan Island,the fragile ecological land of Pingtan Island expanded year by year.The occupation of arable land resources,and the change of land use increased the degree of landscape fragmentation.The change of land use was caused by the ecological vulnerability of the Pingtan Island.Also,the landscape fragmentation was the main cause of the deepening of the ecological vulnerability degree.Through the analysis of ecological vulnerability in Pingtan Island,a series of reasonable countermeasures regarding the subsequent development and construction of the experimentation area,especially in windbreak planting,city planning and land reclamation planning as well as the protection of the cultivated land,land use area and ecological environment have been put forward to improve the island of Pingtan,and to reduce the ecological vulnerability.