Climate Risk Assessment Of Typical Ecosystems In Northeast China

Global climate changes affect the distribution characteristics of precipitation and temperature resources in northeast China,meanwhile it has led to frequent extreme weather disasters and persistent droughts which have adverse effect to the productivity of the ecosystem in northeast China.Hence,it's imperative for the control of climate resource in northeast China to analysis the relationship between the ecosystem and the risk of climate risk and the spatial distribution of climate risk in each ecosystem.In this study,farmland ecosystems,forest ecosystems,grassland ecosystems and marsh ecosystems in northeast China were selected as research objects.By collecting the climate data,vegetation index data and land use data during the growing season in northeast China,the long-term evolution of climate and ecosystem was analyzed.Based on pixel scale,four types of ecosystems were extracted as the main research objects,and the threshold response model between the permanent ecosystem and climate risk factors was constructed.Then the probability spatial distribution of low temperature and cold damage risk,high temperature risk and drought risk are realized which can provide guidance for the adaptive regulation of climate risk in northeast China.The results can be shown as follows:(1)Climate resources are unevenly distributed.Precipitation in the growing season in northeast China generally shows clearly tendency of decreasing while the average temperature,the lowest temperature and the highest temperature all show an increasing trend.Extreme low temperature and extreme high temperature occurred in many places.Precipitation in the growing season in the west of northeast China is less than 200 mm.After 2000,droughts of the growing seasons occurred frequently,especially in 2001(SPEI6=-1.95)and 2007(SPEI6=-2.09).(2)From 1980 to 2015,the main ecosystems in northeast China showed an increase in the area of farmland ecosystem(4.27%)and the decrease in the area of forest ecosystem,grass ecosystem,and marsh ecosystem(-1.62%,-1.88%,and-1.06% respectively).After 2000,the change trend of the ecosystem has slowed down.From 1982 to 2015,NDVI in northeast China presented an interannual increasing trend,with the range of 0.004/10 a.The NDVI of the ecosystem of farmland,grassland and marsh was on the rise,while the NDVI of the ecosystem of forest was on the decline.Ecosystems have a better climate response and can be used for risk simulation.(3)The risk of drought in farmland ecosystem is stronger,and the moderate risk and high risk of drought in farmland ecosystem appear in the farmland of Inner Mongolia grabbing alliance,the farmland of Hegang and Jixi in Sanjiang plain,the farmland in most areas of Songnen plain,and the farmland in northern and western Liaoning province.The risks of low temperature and high temperature of farmland ecosystem are relatively weak.In the forest ecosystem,the drought risk is stronger,and the moderate risk and high risk of drought in forest ecosystem are mostly found in the northern forests of Daxing?an Mountain and Xiaoxing'an Mountain,the northern forests of the Changbai mountains,the forests of the Shuangya Mountain and the Wanda Mountain,and the forests of the western Liaoning province.The risks of low temperature and high temperature of forest ecosystem are relatively weak.Both of the drought risk and the high temperature risk of grassland ecosystem were stronger,and the moderate risk and high risk of drought in grassland ecosystem mostly appear in the western grassland of Hulunbuir,grassland of Ulanhot,the western grassland of Tongliao and the northwestern grassland of Chifeng.The risk of low temperature grassland ecosystem is relatively weak.The drought risk of marsh ecosystem is stronger,and the moderate risk and high risk of drought in marsh ecosystem are mostly found in the plain swamp in the northeast of Sanjiang plain and the west of Songliao plain,and the mountain swamp in the north of Xiaoxing'an Mountain and Daxing?an Mountain.