Comparative Studies On Soil Carbon Flux Under Different Use Conditions In Fixed Sandy Land In The East Section Of Kubqi Desert

Measuring soil CO2emission in the different ecosystems and grasping the environmental impact factors on soil carbon flux are the basis for studying on the characteristics of soil carbon cycle on the regional scale and predicting climate change in the future. In this study, the release characteristics of soil carbon flux under different use conditions in fixed sandy land in the east section of Kubuqi desert was measured using the LI-8100. Temperature, moisture, air relative humidity, rainfall and other environmental factors on soil carbon flux were analyzed. The results which had certain scientific significance could provide some reference information for the research on soil carbon flux. The main results in the present study are as follow:1. There were33kinds of plants in total in fixed sandy land of Kubuqi desert. These33kinks of plants were all xenophobic and mesophyte, which adapted to the sandy environment. There was the high similarity in species composition among the Artemisia community enclosed to protect for15years, the Artemisia community free grazing for15years, and Alfalfa Field originated from the Artemisia community but had improved for6years. The similarity coefficient was between0.56-0.74.2. Dynamic curve within24h of soil carbon flux in each month basically displayed multiple peaks but not obvious under different use conditions in fixed sandy land in the east section of Kubuqi desert. The average dynamic changes within12h of soil carbon flux showed similarly in each month under different use conditions, which presented V-shaped in May, horizontal straight line in June, single obviously peak in July and August, single peak or no-obvious multiple peaks in September and October. The average monthly dynamics curve of soil carbon flux within24h or within12h also showed significantly two-peaks. 3. Whether it was on a seasonal scale, the diurnal variation of scale or time scale, soil carbon flux was different under different use conditions in fixed sandy land in the east section of Kubuqi desert. Compared with enclosure, soil carbon flux was made to change in two different use ways-free grazing and artificial improvement, but the results were different. It means that the release of soil carbon flux was increased under free grazing management, but was reduced under artificial improvement.4. During growing season, because there were extremely significant positive correlation between soil carbon flux and air temperature, soil temperature (0-10cm), soil moisture (0-5cm). Temperature and moisture were important regulating factors of soil carbon flux under different use conditions in the fixed sandy land in the east section of Kubuqi desert. On the diurnal change, soil moisture (0-5cm) played the important regulating role of the soil carbon flux, followed with air temperature and soil temperature (0-10cm).5. It was basically in accordance with exponential equation model between soil carbon flux and temperature under different use conditions in the fixed sandy land in the east section of Kubuqi desert, but not exactly. Soil carbon flux and temperature were in accordance with quadratic equation model in September and October in free grazing for15years of Artemisia community because of negative soil carbon flux. Soil carbon flux and soil moisture (0-5cm) met the first equation model, but the regression effect easily was affected by temperature. Whether it was during the whole growing season or on the diurnal change, synergy of temperature and moisture had a stronger regulating effect in soil carbon flux than viewing them as single factor. It met dual linear equation model between soil carbon flux and the synergy of temperature and moisture.