Temporal and spatial variation of net primary productivity (NPP) and its responses with climatic changes in the Xilingol grassland from 2000 to 2010

Using MODIS MOD17A3 Net Primary Productivity (NPP) data and meteorological data, we analyzed the temporal and spatial variation of NPP, inter-annual changes of climatic factors and the correlative relationship between NPP and climatic factors in Xilingol grassland from 2000 to 2010. The NPP of the Xilingol grassland varied from 0 to 0.5 kg C·m-2 which decreased from east to west. From 2000 to 2010, the NPP fluctuated annual that increased in generaland evenly distributed. The variations of climatic factors in typical and desert grassland were similar. The cumulative average temperature, average relative humility and cumulative sunshine duration in April to August had a downward trend, while the average wind speed had an increasing trend. The cumulative precipitation hadan increasing trend in desert grassland, but had a slight decreasing trend in typical grassland. For most climatic factors, they had more dramatic fluctuations in typical grassland than in desert grassland. For the two types of grassland in the study area, the grassland NPP has very significantly negative correlation (P<0.001) with cumulative average temperature and average daily minimum temperature in April to August, and had slight negative correlation with cumulative sunshine duration and average wind speed, while had strong positive correlation (P<0.001) with cumulative precipitation and average relative humility. In conclusion, the typical grassland had stronger response ability to the changes of climatic factors than the desert grassland.