Abstract: Net primary productivity (NPP) is widely used in evaluating the quality and function of ecosystems. Monitoring the temporal and spatial variations of NPP in ecological engineering region is an important task of ecological construction effectiveness evaluation. Here, we evaluated the spatialtemporal variations of NPP in Xilingol League using sequential remote sensing data from 2000 to 2015 and CarnegieAmes Stanford approach (CASA), and analyzed the impacts of temperature and precipitation on NPP. The results showed that the NPP of Xilingol League ranged from 108.66 to 359.74 g C·m^-2·a^-1 during 2000-2015, with an average growth rate of 13.47 g C·m^-2·a^-1. The average NPP in Xilingol League was 254.18 g C·m^-2·a^-1 from 2000 to 2015, with a spatially descending trend from east to west. The NPP in Taipusi Banner, Duolun County, Xiwuzhumuqin Banner and Dongwuzhumuqin Banner was above 280 g C·m^-2·a^-1, the total areas of these regions covered 40.13% of Xilingol League. Approximately 94.56% of total area in Xilingol League showed an increasing tendency in NPP between 2000 and 2015, while the increased magnitude of NPP in 33.95% of area was more than 120 g C·m^-2. The NPP in Xilingol League was positively correlated with rainfall, while 31.18% of area showed a positive correlation between NPP and temperature. The complex correlation coefficient between NPP and annual temperature and precipitation reached 0.59. We conclude that the NPP in about 55% of area is clearly driven by climatic factors. These regions should fully utilize the positive effects of climate change on ecological restoration. More ecological engineering measures should be adopted in the rest areas where the NPP is relatively insensitive to climate change.

Key words: net primary productivity (NPP), spatiotemporal change, ecological engineering, Beijing-Tianjin sandstorm source area, Xilingol League.