| Under the background of global climate change,the temperature rise caused the influence of different degree to the natural ecosystem,natural disasters and frequent extreme weather events,for the source of Asia's major rivers of the QinghaiTibet Plateau,the change of the natural environment such as imbalance in the structure of solid liquid water constitutes a different degree of threat to the ecosystem,the expanding of human footprints and plateau and the increase of the intensity of human activities,the more aggravated the ecological risk of Qinghai-Tibet Plateau.This article is based on the natural ecological environment conditions of the QinghaiTibet Plateau,in combination with the effects of global climate change on ecosystems,and the negative impact of human activities on the natural landscape reconstruction and ecological environment restoration and protection of positive measures,the combination of 3 classes,a total of 30 selected evaluation index,create the Qinghai-Tibet Plateau ecological risk assessment index system,using high resolution remote sensing data with the official statistics,using the random forest law objectively to ecological risk source of the 13 indicators,10 indicators of the ecological vulnerability and ecological risk management ability of 7 indicators weights were given,ecological risk assessment of the optimization model is used to calculate,The spatial distribution of ecological risk levels on the Qinghai-Tibet Plateau was obtained,and the following conclusions were drawn:(1)Within the scope of the Qinghai-Tibet Plateau,the area of low ecological risk(35.54%),the largest high ecological risk of the smallest(7.19%),very low and low ecological risk area is the sum of the plateau area of more than half(55.84%),the Qinghai-Tibet Plateau as a whole is given priority to with low ecological risk situation,the area of the high value area of risk is relatively small,and relatively concentrated in the spatial distribution of the,is advantageous for the prevention and management of risk.(2)The overall range of human activities on the Qinghai-Tibet Plateau is relatively large,and it shows the characteristics of more southeast and less northwest.However,the areas with high intensity of human activities are very small and concentrated in the middle and low altitude areas,showing the characteristics of low altitude and high intensity,high altitude and low intensity.Under the limitation of natural conditions such as altitude and topography,the disturbance of human activities to the plateau ecosystem is obviously localized.(3)Among the influences of natural factors on the ecological risk of the Qinghai-Tibet Plateau,the ecological risk values corresponding to the four assessment indexes of flood risk,landslide risk,extreme low temperature event intensity and slope increased from northwest to southeast.The ecological risk values corresponding to the nine evaluation indexes of drought index,desertification,extreme high temperature event intensity,annual precipitation,soil organic matter content,accumulated temperature ?0?,vegetation type,vegetation coverage and biological abundance index increased from southeast to northwest.The ecological risk value of the Qinghai-Tibet Plateau is high in the northwest and low in the southeast.(4)On the spatial boundary line,the spatial distribution of the risk values of ecological risk sources in the western end of Qilian Mountain and Nu mountain has a relatively obvious boundary line.The spatial distribution of ecological vulnerability intensity between the western end of the Qilian mountain and the eastern end of the Himalayas has an obvious shape like the "S" shaped dividing line that reverses along the inclined north-south axis.The spatial distribution of ecological management capacity is bounded by the western end of Qilian mountains and the eastern part of Himalayas.The spatial distribution of the risk values of the comprehensive ecological risks takes the southern part of Kunlun mountains as the boundary and divides the high-value and low-value areas of the ecological risks,and take the northern part of Gangdis Mountains,the eastern part of Tanggula Mountains and the northern part of Nyenchen Tanglha as the boundary to divide the middle value area and the low value area of ecological risk.(5)In terms of spatial distribution,the risk values of ecological risk sources on the Qinghai-Tibet Plateau tend to be high in the margin and low in the center,forming a "basin" pattern of risk distribution.The spatial distribution of ecological vulnerability is high in the northwest and low in the southeast.The spatial distribution pattern of ecological management ability value was high in patch area,high in the southeast and low in the northwest.The corresponding spatial distribution of ecological risk value was high in the west and low in the east.The spatial distribution of the comprehensive ecological risk value was high in the north,high in the west and south,and low in the middle and east,forming a "U" shaped distribution pattern with a clockwise rotation of 90°.(6)The eastern part of the Qinghai-Tibet Plateau is a region where human activities are concentrated,and the ecological risks are relatively high.However,the ecological risk value is significantly reduced after the analysis of the ecological risk management capacity,indicating that the ecological risk management capacity plays a significant role and the ecological monitoring and protection effect is remarkable. |
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