Study on Relationship between the Variations of Greenhouse Gases Effiux/ Uptake and the Key Environmental Factors in Mongolia Semi-Arid Grasslands
半干旱草原温室气体排放/吸收与环境因子的关系研究

Static chamber-gas chromatographic techniques were used for measuring efflux/ uptake of CO2, CH4 and N,O in Inner Mongolia semi-arid typical grasslands. Our data indicates that Ihe Inner Mongolia semi-arid grassland represent a significant global source of CO, and N,O, and a significant sink of CH4. There are different patterns of diurnal variations in different season, but the most significant pattern is in summer time or early fall. The most intensive seasonal efflux/uptake of CO2. CH4 and N2O occurs when the soils much wetter for raining or spring-melting. There is a general diurnal variation pattern on CO2 efflux, the efflux is low during the day while the efflux is high in the late evening. The higher the temperature is, the higher the efflux of CO2 occurs; the more prosperous the biomass above the ground is, the higher the uptake of CO2 occurs. The diurnal variation patterns of CH4 and N2O are controlled by the key factors that are soi! moisture and the capacity of transporting oxygen, the range of diurnal uptake/emission flux of CH4 and N2O depends on the variation of diurnal temperature. The significant positive/ negative correlation were found between the seasonal va nation of efflux/ uptake of N2O/ CH4 and the variation of tempera ture(r = 0.4- 0.6). Diurnal range of efflux / uptake of N2O / CH4 decreased for free grazing in Inner Mongolia grasslands, simultaneity, the quantity of annual efflux / uptake of N,O / CH4 decreased either, while the annual efflux of CO, increased.