Spatiotemporal dynamics of grassland fractional coverage in Yili Valley of Xinjiang from 2001 to 2015
YAN Junjie1,2,3， HUANG Hui4， CUI Dong1， LIU Haijun1， CHEN Chen1
1.College of Biology and Geography， Yili Normal University， Yining， Xinjiang 835000， China； 2.Xinjiang Institute of Ecology and Geography， CAS， Urumqi 830011， China；3.University of Chinese Academy of Sciences， Beijing 100049， China； 4.Yili Meteorological Bureau， Yining， Xinjiang 835000， China
Abstract：Based on data of MODIS NDVI and DEM， the fractional coverage of the grassland in Yili Valley of Xinjiangby was extracted using dimidiate pixel model， and its spatiotemporal variations during the 2001-2015 period were investigated. Results showed： 1) affected by persistent livestock overload and worsening of climatic conditions， grassland coverage in Yili Valley continued to decrease in 2001-2015， and the average coverage in the whole area decreased by 11.09% in 15 years. The percent of grassland with reduced coverage mounted to 90.04% while mainly slight decrease with the amplitude less than 0.10. Fractional coverage of grassland located among 1 000-2 250 m in altitude decreased the most on average. 2) The decrease of grassland coverage mainly manifested in the continuous decrease of the high coverage grassland area， and increase in the area as well as descending amplitude of grassland with reduced coverage which is also expanding towards high altitudes. 3) Benefiting from the implementation of grassland conservation policies， decrease rate of vegetation coverage of grassland in Yili Valley slowed down significantly during the period of 2010-2015， though the general downward trend did not change.
闫俊杰,黄 辉,崔 东,刘海军,陈 晨. 2001年～2015年伊犁河谷草地植被覆盖度时空变化特征[J]. 华中师范大学学报(自然科学版), 2017, 51(6): 865-872.
YAN Junjie,HUANG Hui,CUI Dong,LIU Haijun,CHEN Chen. Spatiotemporal dynamics of grassland fractional coverage in Yili Valley of Xinjiang from 2001 to 2015. journal1, 2017, 51(6): 865-872.
2017, Vol. 51 
