Abstract: Based on the data of the monthly average temperature and precipitation from 1953 to 2003 in Xilinhot and applied the model of the net primary productivity(NPP) for the natural vegetation,NPP for the typical steppe taken Xilinhot as a representative region was calculated.The result showed that 1) The simulation results of NPP based on temperature and precipitation were consistent with the aboveground biomass measured in the typical steppe.2) Over last 50 years,the main characteristics of the climate change during the growing season in the typical steppe were with an obvious increase of the temperature in the spring and with a decrease of the precipitation in the summer and autumn.But the changes of the temperature and precipitation had an obvious influence on the annual change of the NPP,rather than on the change tendency of the NPP,which led to an increased range of the NPP changes since 1950s.3) For the typical steppe located in the semi-arid regions,the precipitation was the main limiting factor to the NPP.The rational allocation of water and heat resources would be beneficial to the forage growth in the typical steppe.

Key words: Climate change, Climate change, Typical steppe, Net primary productivity(NPP)