Remote Sensing Evaluation Of Ecological Vulnerability In Qilian Mountains From 2005 To 2018

Global natural environment changes and increasing human activities have greatly affected the ecological environment,leading to the emergence of many ecological problems,making research on ecological vulnerability a hot topic.Ecological vulnerability evaluation is a kind of evaluation of ecosystem conditions from the perspective of vulnerability.Ecological vulnerability is a response degree of ecosystem structure beyond its normal anti-interference ability under the influence of natural factors or human activities.It is an inherent attribute of ecosystem itself.Ecological vulnerability evaluation is a evaluation of ecosystem status from the perspective of vulnerability.Qilian mountain region is an important part of the ecological security barrier of Qinghai-Tibet Plateau in China,which guarantees the ecological security of Northwest China.With the development of social economy and frequent human activities,the impact on the ecological environment is becoming more and more serious,and fragile ecological environment.The goverment has clearly issued relevant plans for ecological management and restoration of the Qilian Mountains,and ecological environment evaluation is the basic work of ecological environmental protection management and restoration.Therefore,it is great significance to conduct comprehensive evaluation of remote sensing and analyze the driving factors of ecological vulnerability of the Qilian Mountains from2005 to 2018.This article takes the Qilian Mountains as the research object,according to the characteristics of its ecological environment and the time series integrity,objectivity,and large spatial span of MODIS sensing data,based on the remote sensing ecological index,four evaluations of fractional vegetation cover,dryness index,ground humidity and land surface temperature are selected.Constructing the ecological vulnerability evaluation system of Qilian Mountains,Using remote sensing and GIS technology,the spatial principal component analysis method is used to obtain weights,calculate the ecological vulnerability index of Qilian Mountains,and systematically and quantitatively evaluate the ecological vulnerability of Qilian Mountains from 2005 to 2018.It aims to reveal the distribution characteristics,spatiotemporal changes and evolution trend of ecological vulnerability in Qilian Mountains,and use the factor detection and interactive detection in the geographic detector to analyze the driving force of the regional ecological vulnerability index and four evaluation indicators,so as to provide reference for regional ecological protection,resource utilization and sustainable development.The results showed that:(1)From 2005 to 2018,the ecological vulnerability of Qilian Mountains were mainly mild,moderate and severe.The high vulnerability area was mainly located in the alpine region,and the low vulnerability area was mainly located in the low altitude and near the urban areas.The annual average of ecological vulnerability index is 0.565,which is in a moderate vulnerability.The spatial distribution of ecological vulnerability index is significantly different,with the characteristics of high in Northwest and low in Southeast.The degree of vulnerability gradually weakens from northwest to Southeast.The low vegetation coverage,high altitude and poor ecological environment in Northwest are the reasons for the high degree of vulnerability.(2)From the change of ecological vulnerability in four time periods,the ecological vulnerability of Qilian Mountains changed from low-level vulnerability to high-level vulnerability in 2005-2010,and the ecological vulnerability increased,mainly with the increase of moderate and severe vulnerable area and the decrease of extremely vulnerable area;the ecological vulnerability changed from high-level vulnerability in 2010-2015,2015-2018 and 2005-2018 The trend of turning to low-level vulnerability is mainly the decrease of extremely vulnerable area and the increase of micro,mild and moderate vulnerable area.In general,the ecological vulnerability of Qilian Mountains has a trend of improvement.(3)In the past 14 years,the ecological vulnerability of Qilian Mountains mainly showed a decreasing trend,The areas with decreased vulnerability accounting for 80.30%and the maximum decreasing rate of 0.04/a.The ecological environment of these regions tended to improve.The areas with increased vulnerability accounted for 19.70%,and the maximum increase rate was 0.05/a.The ecological environment tended to degrade.The improved areas were much larger than the degraded areas.The areas with increased vulnerability were mainly distributed in the middle and east of Qilian Mountains near Qinghai Lake,Daban mountain,Laji mountain and Lenglongling partial area.(4)The average Hurst index of ecological vulnerability in Qilian Mountains from2005 to 2018 was 0.5602,and the positive characteristics were stronger than the negative characteristics.The area of ecological vulnerability continued to decrease accounted for a maximum of 60.22%,and the Qilian Mountains ecological changed to a good direction in the future change.The area of ecological vulnerability decreased to increase accounted for 9.58%.These areas need to be paid more attention and protected by the government departments in the subsequent development.(5)The four indexes all have significant effects on the ecological vulnerability of Qilian Mountains,but the degree of impact is different in different time.In the data of 14 periods from 2005 to 2018,fractional vegetation cover had the greatest impact on ecological vulnerability,followed by dryness index.Ground humidity and land surface temperature fluctuated,indicating that fractional vegetation cover and dryness index were the main driving factors for ecological vulnerability in Qilian Mountains.The q value of any two factors interacting with each other is greater than that of the single factor,which indicates that the multi-factor interaction causes the ecological vulnerability in Qilian Mountains.In general,the ecological vulnerability of the Qilian Mountains has been reduced from 2005 to 2018,the ecological environment protection and comprehensive governance has some progress,but still need to strengthen the protection and constructing ecological security barrier,maintenance of ecological safety and realize the Qilian Mountains region ecosystem benign circulation,promoting the ecological environment sustainable development,the harmonious coexistence between human and nature.