The Research Of Carbon Cycle Of Communities Under Different Utilization In Inner Mongolia Typical Steppe

Carbon cycle of grassland system is one public concern of ecology researches, which is dramatically affected by grazing and other disturbances. In this study, we used closed static chamber method to measure NEE (Net CO2Ecosystem Exchange), ER (Ecosystem Respiration), GEP (Gross Ecosystem Productivity), Rs (Soil Respiration) and other factors of community under different utilization in Xilinhot typical grassland in2012-2013. Our results are as follows:1. The aboveground biomass of perennial herb community decreased significantly with grazing intensity rising, whereas the belowground biomass was increased. The variations of total biomass caused by annual plant synusiae were great between wet year and dry year. In wet year, annual plant synusiae has greatly contributed to total biomass of Server utilized grassland. In contrast, the variation of the below-ground biomass was smaller.2. Grazing had no significant influence on NEE and there were no significant differences among various community utilizations. As grazing intensity increased, NEE had a rising trend. NEE significantly related to photosynthetically active radiation and soil temperature, but no correlation with soil moisture.3. Grazing intensity was positive correlation with soli respiration related positively to temperature. Under water stress, significantly positive correlations were found between soil respiration and soil moisture both Server and Medium utilization, but not in Mild utilization. In addition, grazing had no significant impact on Q10.4. By inter-annual fluctuation in precipitation, grazing had complicated impacts on ER. Among community utilizations, ER was significant higher in wet year. ER in server utilization was significant larger than that of medium utilization in wet year, but in dry year, there were no significant difference among community utilizations. ER showed very significant positive correlation with photosynthetically active radiation, temperature and soil temperature. It’s correlation with soil moisture was sophisticated that ER showed significant positive correlation with soil moisture in dry year, but they had no significant correlation in wet year.5. Grazing had some effects on GEP. GEP in Server utilization was significant little smaller than Medium utilization in wet year, but no significant difference was detected among community utilizations in dry year. Different kind of grassland utilization in wet year was significant lower than that in dry year. The correlation between GEP and environmental factors was roughly consistent with ER.