Ecological Vulnerability Assessment In Hengduan Mountain Area

The Hengduan Mountains spans Yunnan,Tibet and Sichuan provinces,and is located in the southeast of the Qinghai-Tibet Plateau.The region is rich in resources and diverse in species.It is an important barrier area and resource reserve area in China.However,due to the complex and changeable terrain of the Hengduan Mountains,tight mountain folds,obvious vertical differentiation of climate,severe traffic obstruction,high soil erosion and rocky desertification,the local ecological environment has deteriorated significantly.Therefore,the development of ecological vulnerability assessment research in the Hengduan Mountain area and the identification of areas with a high degree of vulnerability are of far-reaching significance for the development of ecological restoration and the construction of the prevention and control system in the region.This study selected 25 evaluation indicators such as vegetation index（NDVI）,population density,precipitation,elevation,GDP per capita,and information accessibility based on remote sensing,meteorological and social statistics data,and based on the VSD model to construct ecological vulnerability Evaluation system.Then use the Analytic Hierarchy Process（AHP）to calculate the index weights,and then conduct a comprehensive analysis of the temporal and spatial laws of ecological vulnerability in the Hengduan Mountains,and calculate and classify the ecological vulnerability of each county based on the county.Finally,based on the comprehensive analysis of ecological vulnerability,the spatial pattern characteristics and evolution trend of ecological vulnerability in Hengduan Mountain are further explored.The main conclusions obtained in this study are as follows:（1）The range of the ecological vulnerability index in Hengduan Mountains in 2000 was 0.219-0.554,with an average value of 0.346;the range of the ecological vulnerability index in 2018 was 0.217-0.565,with an average value of 0.352.The results of the two assessments are mainly based on slightly fragile and slightly fragile.The severely fragile areas are mainly located in the northeast,but the area of the severely fragile areas has increased in 2018,and its area growth rate reached 74.64%.The deteriorating area is also mainly located in the northeast,with an area of 137796km2,accounting for 30.87% of the total area.In short,the spatial distribution characteristics of ecological vulnerability in the Hengduan Mountains are mainly affected by exposure and sensitivity.High exposure is mainly distributed in areas with steep terrain to the north,and areas with high urbanization rates and high population densities in the south.High sensitivity is mainly distributed in the eastern part of the country where rainfall is large and the slope is relatively high.Compared with 2000,both exposure and sensitivity in 2018 have declined to a certain extent,but there is an increasing trend in some areas.Adaptability has a certain effect on the evolution of ecological fragility in the Hengduan Mountains.With the rapid development of social economy,adaptability has a significant trend of enhancement.Compared with 2000,the area of enhanced adaptability is 330203km2,accounting for the total area.Of 73.96%.（2）The average range of the ecological vulnerability index of counties in the Hengduan Mountains in 2000 was 0.296-0.406,and the number of counties in potentially to moderately vulnerable areas were 3,30,52,and 14,respectively.The average value of the ecological vulnerability index in 2018 was between 0.30598-0.422457.The number of counties in different vulnerable areas from potentially vulnerable to severely vulnerable were 4,30,47,17,and 3,respectively.Compared with 2000,the number of counties in 2018 was moderate.The fragile and severely fragile counties have obviously increased,and they are mainly distributed in the northeast,such as Jiuzhaigou County,Songpan County,Mao County,Li County and other counties.This is mainly due to factors such as frequent seismic activity,increased precipitation,and significant intensity of human activities in the region in recent years.（3）Through the analysis of the spatial pattern,the ecological vulnerability of the Hengduan Mountain area presents a relatively significant agglomeration feature,and this agglomeration feature is mainly high-value agglomeration the most significant.In addition,the high-value clusters and low-value clusters of vulnerability have obvious spatial differences.The high-value clusters and hot spots are mainly located in the northeast,and there is a tendency of further deterioration and spread on the time scale;while low-value clusters and cold spots the district is mainly located in the northwest and south areas with flat terrain and less human activities,and compared to 2000,it has improved to a certain extent.For areas with a high degree of vulnerability,it should be regarded as the core area of ecological restoration,and overall planning,strengthening supervision,and prevention and control continue to deteriorate.