Characteristics of CO2 flux and concentration in different ecosystems

By utilizing the micrometeorology data of net radiation, soil heat flux, and CO2 concentration at two heights, temperature, relative humidity, and wind speed measured by the Japanese and Chinese cooperation team at Naiman District of Inner Mongolia, this paper presents a study of the characteristics of CO2 flux and concentration from different ecosystems (namely dune, grassland, light grazing site, medium grazing site, heavy grazing site, maize field and soybean field). First, CO2 flux of these ecosystems is calculated according to the micrometeorology data using the aerodynamics method. Figures of diurnal variations of CO2 flux are compared. Furthermore, in order to analyze the photosynthesis strength and environmental and man-made factors of different ecosystems, the relationship between CO2 concentration and net radiation, temperature and wind speed is investigated. The results show that because of different plant coverage and above ground biomass, CO2 flux from different ecosystems varies greatly. Grazing seriously destroys vegetation conditions of the grassland, resulting in exposure of sand. Therefore, the strength of photosynthesis of this kind of grassland is weak and the range of daily CO2 flux is comparatively narrow. The diurnal variation Of CO2 concentration is closely related to the diurnal variation of net radiation, temperature and wind speed. The former diminishes as the latter increases, but a little slower. The rates of photosynthesis and CO2 transportation can also be influenced by weather conditions. For example, clouds reduce photosynthesis rate, while wind enhances the transportation of CO2 from plants to the atmosphere.