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By utilizing the micrometeorology data of net radiation, soil heat flux, and the CO2 concentration, temperature, relative humidity, and wind speed at two heights measured by the Japanese and Chinese cooperation team at Naiman District in Inner Mongolia, this paper has made a close 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 variation 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. Finally, several conclusions are drawn and the results show that: because of different plant coverage and above ground biomass, CO2 flux from different ecosystems varies greatly; grazing seriously destroyed vegetation conditions of grassland, resulting in the 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 rate 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 the plants to the atmosphere. |
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