The vegetation NDVI variation and its responses to climate change and LUCC from 1982 to 2006 year in northeast permafrost region

Based on the remote sensing data,GIMMS AVHRR and MODIS datasets NDVI during 1982～2006,the annual dynamic and spatial variability of vegetation NDVI in northeast permafrost region were studied.And combined the meteorological data and land use/cover data the responses of vegetation NDVI to climate change and land use/cover change was analyzed.The vegetation NDVI in northeast permafrost was high and had obvious spatial variability.Forest was the principal vegetation type which NDVI was the supreme and mainly distributed in the zone of Da\Xiao Hinggan Mountains and Yi-Chun.The NDVI of lawn which mainly distribute in the southwest was relatively small.The variation trend of vegetation growth in the 25 years in northeast permafrost region was that vegetation NDVI decreased prominently with the temperature rose significantly and precipitation decreased.Precipitation was the main factor influenced vegetation NDVI compared with temperature(the correlation coefficient is 0.74).The northeast permafrost region vegetation NDVI showed four stages by the influences of climate change and human activities from 1982 to 2006.The different vegetation types showed different annual variation disciplines.The discipline of lawn had the biggest volatility in the 25 years.The change of vegetation NDVI had obvious spatial variability.The climate change and permafrost degradation influenced the vegetation NDVI dynamic in the northeast permafrost region.The risen annual mean temperature and decreased annual precipitation had affected the growth of vegetation.In the scale of pixel,the vegetation NDVI had significant correlation between and temperature as well as precipitation and showed temporal and spatial response to the changing climate.The analysis result of LUCC stated clearly that the changes of land cover type in different areas had leaded to increased or decreased NDVI value.Although the LUCC proportion in northeast permafrost region was small,different transformation between the land cover types caused important influence to the size of NDVI value and spatial distribution.