Effect Of Climate Change On Ecosystem Stability In Three River Source Region

Three river source region(TRSR)is one of most sensitive ecosystems in China.TRSR,as the source of the Yangtze River,the Yellow River,and the Lantsang River,is very important to the entire China and Indo-China Peninsula,even the whole world.This research established the system of ecosystem stability evaluation,calculated the spatial and temporal distribution characteristic of different ecological and environmental factors,and analyzed the situation of ecosystem stability in the TRSR through PSR model.The Results showed that:(1)The temperature in the TRSR had an increasing trend,and the mutation of temperature was happened in 2000.The temperature of four seasons all increased,and winter was the most significant.The precipitation in the TRSR was also increasing with fluctuation during the study period.Precipitation increased in spring and summer,while the adverse tendency was shown in the autumn.The precipitation in most periods had an increasing trend,except the 1980s.The water situation in the TRSR was relatively stable,with a slight decreasing trend in SPEI value.Most regions in the TRSR had a wetting trend.Most area of Yangtze River and Lantsang River showed a slight wetting trend,and about 25%area of Yellow River had a drought trend.(2)The value of average vegetation NPP in the TRSR is 209.62 g·m-1·a-1,and the vegetation status in the Yellow River and the Lantsang River are better than the average level of the TRSR,and the vegetation status in the Yangtze River is the worst.In 1982-2013,the vegetation NPP in the TRSR had an increasing trend,which was same as the Yangtze River,the Yellow River and the Lantsang River.The increase of yegetation NPP was significant in summer.The vegetation NPP was strongly correlated with temperature,and weakly correlated with precipitation.Both of them were mainly positive correlated.(3)The landscape type in the TRSR was mainly grassland,and the unuseland took the second place,while the urban area was the minimum,which was the same in different sub-regions.During the period of 1980-2015,the forest,grassland and water area had a decreasing trend,while the urban area and farm land showed a significant increasing trend.In brief,the regions with vegetation cover degenderated from 1980 to2015.What's more,the landscape pattern index keeps stable during the study period,and each sub-region had the same phenomenon.Total ecological service value in the TRSR decreased first,and then increased.From 1980 to 2015,the ecological service value kept stable with a slight decrease.The ecological service value of the vegetation and water area decreased in the study period,while the value in the unused land and farm land increased.The ecological service value in the Yangtze River was the highest and the Lantsang River was the smallest.(4)The ecosystem stability of the TRSR was in the status of potential unstable condition.The ecosystem stability in the TSRS kept stable,with an increasing trend first and then a decreasing trend under climate change in recent years.The climate factors made positive contribution to ecological restoration under climate change.Although a lot of environmental protection projects had been carried out in the TRSR,human activities still played the negative role,owing to the incrase of population,economy,and land reclamation rate.Chinese government should implement the environmental protection policy and ecological restoration measures.In order to enhance the ecosystem stability of the TRSR and make more sense to ecosystem under climate change,we should strengthen management.