| Tibetan plateau is an important ecological security barrier in China and even in Asia.The study on the ecological risks of land cover change in Tibetan plateau is an important part of the scientific research on global change,and also a scientific basis for ensuring the ecological security and functional stability of the plateau.Revealed the situation that ecological risk of Tibetan plateau under the influence of land use/cover change with the effect of climate change and human activity,in order to better implementation of the Tibetan plateau development and management,and provide strong support for territorial planning,strive to be the basis of maintaining Tibetan plateau ecological stability,take plateau’s advantage of recreational and educational values,make its development under the precondition of ecological security in moderation.Based on the ESA project land cover data on climate change(CCI-LC),using the software such as ArcGIS10.5 and Fragstats 4.2 as the foundation of the analysis of Tibetan plateau the overall change of land use and landscape pattern change of time and space,on the basis of risk evaluation unit division,the Tibetan plateau landscape ecological risk assessment model is established,from 1992 to 2015 are analyzed in detail Tibetan plateau landscape ecological risk of the spatial distribution and temporal variation characteristics.The result of research shows that:(1)The distribution of landscape ecological risks on Tibetan Plateau has an aggregation effect,showing the high-high concentration in the northwest of the plateau,and the low-low concentration in the southeast of the plateau,with a gradient distribution law.On the whole,it reflects that the risk in the northwest is high,while it is low and in the southeast.The feature of distribution with regard to landscape ecological risks is closely to the natural terrain of Tibetan Plateau,which is mainly affected by the natural geographical conditions.(2)From 1992 to 2015,the landscape ecological risk of Tibetan Plateau showed a downward trend on the whole,with the average ecological risk dropping by 1.89%,which is mainly manifested in the reduction of the high and the higher risk areas,and the expansion of the area of the low and the less lower risk areas.The main reason for this change is the influence of the warming and wetting process of the Tibetan plateau and ecological construction on the land cover structure since 1990s(3)There are significant differences in the distribution and features of landscape ecological risks change on Tibetan Plateau.The value regions with higher landscape ecological risk value mainly exist in the marginal areas where different terrains meet.The low level of ecological risk accounting for the largest proportion is the forest land,while the highest percentage of high of that level is the bare land,glacier and snow cover.The declining rate of bare land with high ecological risk grade was the highest,followed by grassland,which reflected that the change of bare land and grassland had the most significant impact on the landscape ecological risk of Tibetan Plateau.(4)The comprehensive ecological risk of land use is high in the northern and northwestern areas of the Tibetan plateau,and the ecological risk value in the southeastern part of the plateau is low on the whole,but there are also concentrated areas with relatively high ecological risk in local areas,with the focus on indicators that have a greater impact on regional ecological risk.(5)For the management of land use ecological risk on Tibetan plateau,it is necessary to pay attention to the dynamic supervision of land use change on the plateau,implement corresponding protection and construction policies for each ecological risk level,establish a long-term management mechanism for the plateau ecological risk,and finally achieve sustainable development of Tibetan plateau. |
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