Effects Of The Construction Of Qinghai-Tibet Railway On The Vegetation Cover And Eco-Resilience

The Qinghai-Tibet Plateau is known as the "Third Pole of The World",is an important geographical unit in China,is considered an important "indicator" of global change.Plateau vegetation in the hypoxia,low temperature and other environment constraints,formed unique adaptation strategies.As one of' the most complex engineering projects in the plateau area,the influence of Qinghai-Tibet Railway on the vegetation ecosystems in the plateau area,has attracted much attention.Since 2001,How dose the Qinghai-Tibet Railway impacted the vegetation and enviroment?Does it cause the surrounding vegetation to degrade?There's still some doubt.Based on these situations,this paper selected the 10km buffer along the Qinghai-Tibet Railway as the study area,using the Landsat NDVI time series data from 1995 to 2014 to analyze the relationship between the distribution and variation of the vegetation along the railway,and the trend with railway constructing.The temporal and spatial characteristics of regime shift and the eoc-resilience in the study area were analyzed.The causes of vegetation change in the study area were analyzed by means of temperature and precipitation and socio-economic factors(1)The area of meadow ecosystem is the largest in the area of 10km along the Qinghai-Tibet Railway,and the average NDVI of each vegetation type is:wetland>farmland>meadow>shrub>alpine>Grassland>desert>bare land;NDVI in the study area is low,the vegetation growth condition is poor,NDVI is higher in south than north,NDVI high and low value shows aggregation distribution.(2)In order to analyze the influence of railway construction on the study area,buffers were created 0?100m,100?250m,250?500m,500?100m,1000?2000m,2000?5000m,5000?10000m,and the type of vegetation ecosystems in the study area showed an upward trend,which was consistent with the rising rate of the Qinghai-Tibet Plateau.In the period from 1995 to 2014,the NDVI of the study area showed an upward trend,the railway construction has no obvious effect on the vegetation in 10km buffer along the railway.From the NDVI time curves of each buffer,it can be seen that the average NDVI of each buffer in the study area be different from 2001.The farther away from the railway,the average NDVI higher,indicating that the railway construction has inhibitory effect on the growth of vegetation along the area,the scope of action is concentrated within 1km along the line,the most serious damage to the area within 100m.(3)From 1995 to 2014,the area of vegetation growth improvement area in the study area is more than deterioration area 3 times.The area of NDVI is mainly distributed in Golmud and its surrounding area,Mountainous areas,Dangxiong-Lhasa on both sides of the foothills,reducing the area mainly for the railway construction area,along the residential area and Nagqu-Dangxiong section of the pastoral areas;different ecosystems,desert and bare land 20 years NDVI changes the slightest,wetland and farmland ecosystem NDVI increased most significantly.(4)Through the sequential T test and the ecological resilience calculation,it is found that the area of NDVI along the Qinghai-Tibet Railway is mainly distributed in the residential area,the northern Tibet pastoral area and the part of the valley area,which is the concentrated area of human activity.It can be seen that the change of vegetation along the railway line is mainly due to the activation of human activities along the line.The vegetation change concentrate in urban and the pastoral area,and is larger than that on the railway side.The wetland ecosystem due to the low resilience and high NDVI should be used as ecological protection and monitoring,While the desert ecosystem is due to its low NDVI,high resilience,it is difficult to restore.(5)Most of the areas of the study area are "the warmmer and wetter,vegetation expansion;the warmer and drier,vegetation degeneration";railway construction sphere of influence is not as wide as climate change,and in human activity area,vegetation is dominated by human,there are three different type of human impact vegetation:the promotion,maintenance and destruction.