Abstract: Horqin Sandy Land is a key area for the project of desertification prevention and control in China. In recent years, ecological engineering construction, human activities and vegetation growth in this area have been affected by climate change to some extent. Understandingdynamic change of regional vegetation can provide scientific basis for the comprehensive control of the sandy land and reasonable construction of ecological engineering. Consequently, the spatialtemporal variations and their driving factors of NDVI in Horqin Sandy Land were analyzed based on the dataset of NOAA-NDVI and MODIS-NDVI from 1981 to 2015, as well as meteorological and socioeconomic data. The results showed that from 1981 to 2015, NDVI showed a fluctuating increase trend (with a growth rate of 0.00114 a^-1). Spatially, areas with increasing NDVI(accounting for 68.8% area) were mainly located in the southeast margin and part of the central region, while NDVI of the northwest margin of the study area was decreasing. The change process of NDVI in desertification areas of different degrees was first decreased (1981-2000) and then increased (2001-2015), indicating that vegetation destroyed in the early stage was restored in the later stage. Results of driving force analysis showed that precipitation and temperature were the factors driving NDVI changes in some areas of Horqin Sandy Land. Population change and the implementation of ecological engineering drove the spatial-temporal change of vegetation in this region. However, economic development was not a major factor driving vegetation change in this area.

Key words: biomass., improvement effect, physico-chemical properties, organic matter, iron tailing