| With the rapid development of population and social economy,the regional ecological environment is changed with unprecedented scale and speed.The contradiction between people and the ecological environment has become increasingly prominent.The ecological environment generally becomes a problem that cannot be ignored and research on the ecological environment vulnerability has become a research hotspot.Based on a comprehensive analysis of the results of previous studies,this study take the Yangtze River Region in Northwest Sichuan,the main ecological barrier in the upper reaches of the Yangtze and Yellow Rivers,as a research prototype by using Remote Sensing and Geographic Information System and acquire many years of natural environmental conditions and socio-economic data in the study area.On the base of summarizing characteristics of the ecological environment vulnerability of study area,this study constructed a set of evaluation index system for ecological environment vulnerability in the study area.Combining the RUSLE model,information model,and NPP remote sensing estimation model,this study achieves the quantification of index data and evaluates the ecological vulnerability of the study area using DEMTAL-AHP weight determination method.Based on the results of quantitative evaluation,this study analyzes the spatial distribution characteristics,spatial evolution characteristics of the ecological environmental vulnerability assessment results in the study area and explores relationship between social economic factors and ecological environmental vulnerability.The research results have important theoretical and practical significance for ensuring the sustainable development of the natural resources and ecological environment of the Yangtze River Region in Northwest Sichuan and provide important scientific basis for the relevant departments to formulate ecological protection systems,ecological restoration measures and ecological development plans.The main research results obtained in this paper are as follows:(1)Starting from the two aspects of the natural environment and human factors,an evaluation index system for the ecological environment vulnerability of the source regions of rivers in the northwest of Sichuan Province was constructed and an ecological environment vulnerability evaluation model was built using DEMATEL-AHP method.(2)According to the spatial distribution of ecological environmental vulnerability,the extremely vulnerable areas are mainly distributed in the central Shiqu county,southern plateau pure animal husbandry and the semi-agricultural and semi-pastoral desertification areas in the valley,the Ganzi county and surrounding river agriculture valleys,plateau landscape to high altitude mountainous terrain area of the northeast of Ruoergai county,the Seda county and Rangtang county river valleys,the Aba county and the surrounding agricultural arable land.(3)A dynamic analysis of the evaluation results using mass transfer,coefficient of variation,and spatial autocorrelation found that from 2000 to 2015,the migration of the fragile nature of the ecological environment in the study area is 4.82 km,and the coefficient of spatial variation is mostly distributed between 0 and 0.17.It shows that the level of the overall ecological environment vulnerability in the study area is relatively stable,there is no large-scale change,and the overall ecological function is relatively complete.However,due to the influence of external factors,the fragility of the regional ecological environment has fluctuate.During 2005 to 2010 the vulnerability fluctuations was the most obvious,and the overall vulnerability of the ecological environment showed a upward trend.The ‘high-high’ and ‘low-low’ regions of the eco-environmental vulnerability index were positively correlated in space,and the spatial correlation was relatively obvious.The degree of differentiation is low.(4)According to the distribution of ecological environment vulnerability index in different types of land cover,the highest proportion of unexploited land in negligible vulnerable and light vulnerable areas is 81.49%.The moderately vulnerable areas are distributed in all types of land cover,and the forest land has the highest proportion of moderately vulnerable areas,among which woodland,shrubs and other forest lands account for 28.06%,26.28% and 23.09% respectively.Severely vulnerable areas and extremely vulnerable areas have strong regularity and are concentrated in areas where human activities are more concentrated.According to the proportion of changes in the ecological environment vulnerability at different levels in different types of land cover,the proportion of the increase in the eco-environmental vulnerability index of residential areas is 52.38%,which is the highest for all types of cover types.39.83% of the regional agricultural ecological vulnerability index showed an upward trend.The ratio of the ecological vulnerability index increased in the grassland and woodland ranged from 26.28% to 39.90%.(5)The determinable coefficient of population and the total output value of agriculture,forestry,animal husbandry,subsectoral fisheries,and eco-environmental vulnerability index are relatively high,0.4628 and 0.5045.Agricultural activities,excessive grazing,urban expansion,abusive use of forest and grass resources,road construction,mountain mining and other human activities will have a negative impact on the ecosystem.It can be concluded that with the increase of the population,the fragility of the ecological environment will continue to rise.However,with the increase in the total output value of agriculture,forestry,animal husbandry,and fishery,the rate of increase in ecological environmental vulnerability will gradually decrease. |
