Ecosystem Risk Assessment Of Alpine Grassland

Due to the influence of human activities and extreme climate change,the alpine grassland ecological environment has been deteriorated quickly.As a sensitive area of global climate change,the ecological environment of the Qinghai-Tibet Plateau is facing unprecedented challenges.Ecological risk assessment can measure the potential deterioration risk of ecological environment because of human activities and extreme climate,and analyze and evaluate the main risk sources.Also that can,explore and predict the formation mechanism of ecological risk and mitigate the loss caused by the risk sources.The environmental protection managers can get the help to formulate corresponding protection and protect ecological security against the harm caused by ecological risk.Therefore,effective measurement of the ecological risk level of the alpine grassland has important scientific reference significance for the ecological security protection of the Qinghai-Tibet Plateau.In this thesis,GIS(Geographic Information System),RS(Remote Sensing)technology and statistical analysis method has been used in the research area which is,the Gannan in the eastern part of the Qinghai-Tibet Plateau.The remote sensing image data,the field measured data,the statistical Yearbook data,the soil survey data and the other related data have been used too.So,the drought,the rodent damage and the soil erosion were selected as natural risk sources,at the same time,the non-grazing human activities and grazing carrying capacity were the risk sources of human impact.The probabilistic loss model is used to evaluate the ecological risk of single risk source on alpine grassland.Finally,the spatial and temporal dynamic evaluation of the ecological risk of alpine grassland is carried out by using the method of entropy and GIS spatial analysis.The results of the single ecological risk source indicate that:1)For drought ecosystem risk assessment,the drought risk of alpine grassland in the Gannan region showed a downward trend in 2000-2015;and the drought risk of the northern and the eastern Gannan region gradually decreased,while the drought risk of the southern and the western Gannan region showed an rising trend,but only in the southeastern part of Gannan region,Diebu and Zhouqu,northern Zhuoni and southern Maqu showed significant changes.2)For the ecosystem risk assessment of rodent damage,the risk of rodent damage in alpine grassland of Gannan region showed a decreasing trend in 2000-2015;and the risk of rodent damage in northern Gannan region showed a decreasing trend,while that in southern Gannan region showed an increasing trend,while the risk of rodent damage decreased significantly in northern Gannan region,while the risk of rodent damage in most areas did not increase significantly except in parts of Maqu county.3)For the risk assessment of soil erosion,the risk of soil erosion of alpine grassland in Gannan region showed a decreasing trend in 2000-2015.The risk of soil erosion in the northern part of Gannan region decreased significantly,while in the western part of Gannan region,the risk of soil erosion increased significantly.4)For the risk assessment of non-grazing human activities,the risk of non-grazing human activities in the alpine grassland of Gannan region decreased in 2000-2015,and the risk of non-grazing human activities increased from northwest to southeast,from southwest to northeast.5)For the risk assessment of grazing carrying capacity,the risk of grazing carrying capacity of alpine grassland in Gannan region increased from 2000 to 2015;and the risk of grazing carrying county of Xiahe alpine grassland decreased insignificantly;the risk of grazing carrying county of Luqu,Maqu and Duipu increased significantly;the risk of grazing carrying county of Zhuoni and Lintan increased insignificantly;and the risk of grazing carrying county of Zhouqu increased insignificantly.The change of region is significant,but the decrease of region is not significant.The results of the comprehensive ecological risk sources showed that:The results of the comprehensive ecological risk sources analysis of alpine grassland showed that the ecological risk of alpine grassland in Gannan region decreased from 2000 to 2015.In the next 15 years,the sub-low ecological risk and the medium ecological risk of alpine grassland may increase,while the low risk,sub-high risk and high risk will decrease.At the same time,the ecological risk of alpine grassland in Xiahe and Maqu western regions will decrease significantly.The ecological risk in some areas of Luqu,Diebu and Zhouqu increased significantly.Overall,the ecological risk of alpine grassland in the western Gannan region changed significantly compared with that in eastern Gannan region,and the natural risk source was the main reason for the change of comprehensive ecological risk of alpine grassland.