Influences Of Warming And Nitrogen Addition On Soil Respiration And Plant Community In Inner Mongolia Desert Steppe

Global climate change has become an indisputable fact. The study of simulated global warming and nitrogen addition on was conducted indesert steppe of Inner Mongolia in order to understand the impact of warming and nitrogen addition on soil respiration and plant communities, to explore the desert steppe ecosystem reponse to global climate change, and to provide the basis for sustainable management and use of desert grassland ecosystem. The major results were as follows.1Soil temperatures in the depths of0～10cm,10～20cm and20～30cm increased significantly (P<0.05) in warming plots in2012and2013, and compared with non warming plaots soil average temperature increased by0.56℃,0.50℃,0.35℃in warming plots. The increases of soil temperature declined with the soil depth. Warming reduced soil moisture at0-10cm layer (P<0.05). There were no effects on soil temperature and moisture with nitrogen addition.2Warming weakened soil respiration; nitrogen addition on soil respiration is a promoting role. However, statistics showed no significant difference (P>0.05). Of the interaction between warming and nitrogen addition on soil respiration was uncertain. During the experiment, the day dynamic trend of growth peak on soil respiration was roughly same, showed a single peak curve, and the peak occurred at15:00～18:00, the minimum value occurred in the night between0:00-3:00. Soil respiration in daytime was higher than night.3Warming and nitrogen addition changed the height, coverage, frequency, density of the species in the two years study. But warming, nitrogen addition and interaction between warming and nitrogen addition had no affect on plant community composition and structure. Warming and nitrogen addition had no significant influence on aboveground biomass of plants (P>0.05). Nitrogen addition and warming interaction increased significantly the aboveground biomass (P<0.05). Warming made the belowground biomass of0-30cm decline significantly (P<0.05), while belowground biomass of20～30cm increased significantly (P>0.05). Nitrogen addition significantly increased belowground biomass (P>0.05). Warming and nitrogen interaction had no change on belowground biomass and its distribution. 4Warming msde Margalef richness index, Shannon-wiener diversity index, Pielou evenness index of plant communities decrease; Nitrogen addition made the richness of plant communitiesincrease; Interaction between warming and nitrogen addition on the change of plant community diversity index was less obvious. The Margalef richness index and Shannon-wiener diversity index of perennial grasses increased. Nitrogen addition made Margalef richness index increase and Pielou index and Shannon-wiener diversity index decrease for most species functional groups. Interaction between warming and nitrogen addition had no effect on the diversity indice of species functional groups.