The Initial Impact Of Simulated Warming And Simulated Grazing To Soil Respiration And Community Characteristics Of Alpine Meadow

We examined the effect of experimental warming and grazing addition in aKobresia humilis meadow for study by the International Tundra Experiment(ITEX)under field conditions. In a simulated global warming condition，we research theeffect of warming by four different gradient and explore the alpine meadowecosystem to global climate change response mechanism for our Global Change andGrassland Ecosystems provide long-term research platform. The result of papershowed:（1）During the experiment from on May2013to September2013,compared with thecontrol,both air temperature and soil temperature increased significantly inside thegreenhouse Among the different treatments, temperature change is inconsistencies,but,was gradually increasing with the greenhouse from large to small. The results ofvariance analysis showed: at the two factors, variation of temperature was notsignificant(P>0.05).Under two factors, the change of four treatments weredifferent,but substantially air temperature was higher than soil temperature. Thechange trends of the10cm air humidity: Humidity gradually declined from A to D.（2）Seasonal dynamics of soil respiration, temperature and control treatment wereanalogous. But the soil respiration was higher than the control treatment. Grazing, theaverage value of soil respiration rate of A~D treatment and control treatment was4.205,4.274,4.553and3.998μmol·m-2·s-1;warming,the average value was4.123,3.966,4.282and3.886μmol·m-2·s-1. Soil respiration rate was positively correlated with soiltemperature at5cm.Q10value showed: grazing and each treatment of grazing weregreater than warming and each treatment of warming. There was no significantcorrelation between soil respiration rate and air humidity（P＞0.05）.（3) The soil respiration rate were increased by Warming, grazing and the interactiveeffects of warming and grazing, but the variance analysis showed: the difference wasno significant (P>0.05).（4) Warming and grazing did not significantly influence those in plant community.Dominant species, the status and function in the community of dominant species and main associated species did not change （P＞0.05). Execpt for treatment D,experimental warming did not improve the Pielou evenness and Shannon-Wienerdiversity index of plant community; experimental grazing improved the Pielouevenness and Shannon-Wiener diversity index of plant community; experimental theinteractive effects of warming and grazing improved the Pielou evenness andShannon-Wiener diversity index of plant community, decreased the Species index.（5) The effect of warming and grazing did not improved the aboveground biomass.Between species diversity and aboveground biomass had a positive correlation, whichwas illustrated this point in treatment D. Distribution of undergroud biomassdecreased vertically, most of the biomass concentrated in the surface. Meanwhile, forthe changes of surface biomass showed, warming was main effect, to the contrary,effcet of grazing was greater than warming.