Monitoring phenology and vegetation dynamics in Inner Mongolia grassland using Terra MODIS imageries

摘要

Inner Mongolia grassland, one of the most important grazing regions in China, has long been suffering a serious threat of land degradation and desertification, mainly due to overgrazing.For understanding the vegetation response over a long period of time, this study evaluated the phonological change of vegetation by analyzing the 16-day composite normalized difference vegetation index (NDVI) derived from the Terra-MODIS satellite images during 2002-2012.The start and end dates of growing season had been set as the time when NDVI value reached 20％ seasonal amplitude from the minimum level.The results showed that the start dates in desert steppe were earlier than typical and meadow steppe area.Meanwhile the season length tended to be longer in desert steppe, shorter in meadow steppe, and stable in typical steppe region.The heterogeneous spatial distribution should be noticed, expressly in the northeast and middle part of Inner Mongolia.