Monitoring and assessment of vegetation variation over the Ili River Basin in Xinjiang

The spatial- temporal distribution of vegetation variation in the Ili River was investigated using the MODIS / NDVI data from 2000- 2013. Combining the meteorological data,we discussed the relationship between growing- season NDVI and climatic variables. The results were shown as follows: 1) NDVI decreased at a rate of 0. 8% /10 a in the Ili River since 2000,in which the degradation of grasslands slightly forward than meadows,thickets and woodland. 2) NDVI decreased and increased area covered about 11. 45% and 8. 38% of the whole study area. The decreased area was mainly distributed in middle and lower reaches of the Turks River and the surrounding areas of Kunas River. NDVI increased area was mainly distributed in the surrounding areas of Yining city and the Horgos River. 3) There was an insignificant correlation between NDVI and climatic factors( temperature and precipitation) around the Yining meteorological station. The results also revealed that there were a strong positive significant correlation between NDVI and precipitation and a significant negative correlation between NDVI and temperature in Zhaosu meteorological station. The main reasons for the negative change of vegetation in the Ili River were the heat and dry tendency of climate.