Abstract: Using static dark enclosed chamber technique, the fluxes of CO2 from temperate grassland such as meadow, Leymus chinensis grassland and Stipa grandis grassland and their major environmental factors were measured in Xilin River Basin of Inner Mongolia under the abnormally dry circumstances from June to September in 2001（rainfall was less than 1/6 of that in historical normal years）. Then the correlation between the emissions of CO2 and major environmental factors were studied. The results showed that there was a little or no correlation between the monthly fluctuation of the emissions of CO2 from grassland and air temperature and topsoil temperature during the period of rapid growth of grassland, however the daily variation of CO2 flux was significantly positively correlated with the earth's surface temperature and air temperature. And the relation between the emissions of CO2 and soil temperatures at the depth of 5 cm and 10 cm was not obvious. As for the response of the fluxes of CO2 to annual precipitation, the average emissions of CO2 dropped off from 268.7, 211.6 to 181.4 mg?m-2?h-1 in meadow, Leymus chinensis grassland and Stipa grandis grassland, respectively. That meant precipitation was an important environmental factor influencing the fluxes of CO2 from grassland. It was also found that there was a close and positive correlation between the emission of CO2 and other environmental factors such as soil water content, organic content and total nitrogen content in different soil layers.

Key words: Carbon cycle, Carbon dioxide, Temperate grassland, Biogeochemistry