The variation of net primary production and leaf area index over Xinjiang Autonomous Region and its response to climate change

The spatiotemporal variations in the vegetation within the Xinjiang Uygur Autonomous Region from 1982 to 2000 were quantified using satellite remote sensing,AVHRR LAI and NPP data from the Carnegie-Ames-Stanford Approach.The results show that the spatial distributions of both NPP and LAI are strictly controlled by the precipitation and are negatively correlated to air temperature.This reflects the topographical characteristics of the vegetation in the arid inland region under limited precipitation.In contrast to the 1980s,the warming trend that occurred in the 1990s and the precipitation both followed an overall increasing trend.To the north of 42 N,this warm-wet climate shift was more obvious.Corresponding to this climate pattern shift,the vegetation increased markedly,with a maximum NPP increment of 45 gC m-2 a-1.However,vegetation showed a different response to the air temperature and the precipitation on the timescale of interannual chan-ges.The precipitation mainly affected the peak changes in the vegetation,whereas the total temporal variation trend was principally controlled by the air temperature.Temperatures in three sub-regions increased markedly,but the precipitation did not follow any obvious trend.A marked increasing trend(P0.01)occurred in vegetation and corresponded to the changes in the temperature.