Eco-vulnerability Assessment And Spatial Pattern Optimization

The island is an independent region,and its special location determines the special geographical environment.Compared with the land,the natural factors such as vegetation,soil,and climate are different.The social and economic conditions of the islands are more different from those of the land.The way of life and work of the people living on the island directly affect the ecosystem of the islands.With the rise of island tourism and the development of marine resources,the intensity of island development has increased in recent years,and then the island’s ecosystem has been threatened.It is urgent to assess the vulnerability of the island’s ecosystem.At the same time,many scholars have begun to pay attention to the protection of islands.More and more people pay attention to the special ecological significance of islands.Establishing a valuable island ecosystem assessment framework and conducting pilot assessment of the assessment framework is essential for island ecosystem vulnerability assessment.At present,our country is still at the stage of investigation on islands.The research on islands started late and the number was small.At present,there is no systematic theory and method for island ecological vulnerability assessment,and the evaluation is mostly qualitative analysis on macro level.In this paper,through the selection of exposure-sensitivity-adaptation model,referred to as ESA model,the index system is selected under this model to construct an index system for assessing the ecological vulnerability of highly developed islands.South Changshan Island and North Changshan Island in Shandong Province and their surrounding sea areas are the research areas,which have the typical characteristics of high-intensity island development.Through field investigation,field investigation,data collection and other related work,a pilot evaluation was carried out in this area using the index system to explore the rationality of the evaluation results.This paper also uses Bayesian network analysis model to carry out conditional probability analysis of each index affecting the ecological vulnerability of islands,and evaluates the impact degree of each index on the ecological vulnerability from the perspective of probability.The driving force of each index to ecological vulnerability was evaluated by the method of entropy difference.Finally,through the analysis of driving forces,the spatial expression of ecological vulnerability can be optimized.The results of this study are as follows:(1)By evaluating the exposures,sensitivities and adaptabilities of the islands,and combining with the characteristics of high-intensity developed islands,natural and human factors indicators were selected.Based on literature review,field investigation and previous studies,a assessment system for the ecological vulnerability of highintensity developed islands with 23 assessment indicators was constructed.(2)The pilot evaluation of Changdao island in Yantai City of Shandong Province is carried out by using the established assessment system.According to the results of ecological vulnerability assessment of Changshan Island,the ecological vulnerability of Changshan Island is low,which shows that there are not vulnerable,critical vulnerable and slightly vulnerable areas.Among them,there are no vulnerable areas in the sea area,and the adjacent sea areas are all non-vulnerable areas(1219 hectares)and critical vulnerable areas(2528 hectares).The island land area includes non-vulnerable area(412 hectares),critical vulnerable area(1445 hectares)and mild vulnerable area(368 hectares).Among them,the central and western part of North Changshan Island and the southeastern part of South Changshan Island are subject to more external interference,and their own attributes are vulnerable to external influences,which makes the ecological vulnerability of these areas relatively high,and the ecosystem is slightly fragile.The coastal areas of the island land are mostly in a non-fragile or critical condition.Although these areas are greatly disturbed by the outside world,due to their own attributes,these areas are extremely vulnerable to external influence and change,so the ecosystem vulnerability is low,and the ecosystem is not fragile or slightly fragile.Comparing North Changshan Island with South Changshan Island,the ecological fragile area of North Changshan Island accounts for 29.97% of the total area of North Changshan Island,while the ecological fragile area of South Changshan Island accounts for 8.79% of the total area of South Changshan Island.The ecological fragility of North Changshan Island is higher than that of South Changshan Island,and the ecological condition of North Changshan Island is more vulnerable to external influences and changes.(3)Using Bayesian network analysis model,the conditional probability of the combination of evaluation results and evaluation indicators is obtained.The entropy difference of NPP,steep slope ratio,groundwater,soil and island land development is 0.21,0.55,1.05,1.13 and 1.42,respectively.The entropy difference of NPP and steep slope ratio is the smallest and is less than 1,which indicates that the correlation between NPP and steep slope ratio and ecological vulnerability is the highest.(4)NPP and steep slope ratio are selected as the key indicators affecting ecological vulnerability assessment.According to the state subset of key indicators and combined with the results of ecological vulnerability assessment,the first-level optimization zones(which can be optimized to non-vulnerable areas)and the second-level optimization zones(which can be optimized to critical vulnerable areas)are selected to reduce the ecological vulnerability of the region.There are very few primary optimization areas for ecological vulnerability of Changshan Island,with only 4 hectares.Among them,there are 3 hectares in North Changshan Island and 1 hectare in South Changshan Island.There are 184 hectares in the area of the second-level optimum area,and the second-level optimum area is mostly distributed in North Changshan Island.North Changshan Island has 126 hectares of secondary optimum area,while South Changshan Island has 58 hectares of secondary optimum area.These areas should be the key areas of ecological protection.It is suggested that local governments strengthen the ecological protection of these areas,restrict the development,and guarantee the harmonious development of economy,society and ecological environment.