| Abstract: | Using dark enclosed chamber technique,CO2 fluxes from meadow,Leymus chinensis grassland and Stipa grandis grassland and major environmental factors were measured in Xilin River Basin of Inner Mongolia under abnormally dry circumstances during June to September 2001,when rainfall was less than 1/6 of that in normal years.Results showed the diurnal variation of CO2 flux was significantly positively correlated with the earth's surface temperature and air temperature.As to the response of the fluxes of CO2 to annual precipitation,the average CO2 emission decreased from 268.7,211.6 to 181.4 mgm-2 h-1 in meadow,Leymus chinensis grassland and Stipa grandis grassland,respectively,with a decrease in annual precipitation.Therefore precipitation was an important environmental factor influencing CO2 flux from grassland.We also found close positively correlation between CO2 emissions and soil water content,organic content and total nitrogen content in different soil layers.However,there was little correlation between the monthly fluctuation of CO2 emissions with air temperature,topsoil temperature and soil temperatures at 5 and 10 cm soil depth. |
