The global climate has experienced drastic changes in the 20^th century, and it has been suggested that even more will take place in the 21^st century if the greenhouse gas emission rate remains at or exceeds the current level. More research has been focused on the global warming with a goal to assess the influence of the climate change on ecosystem processes and functions from different aspects. Microorganisms are the most abundant and diverse group of life on our planet and play specific and key functional roles in ecosystems including decomposition, element cycling, decontamination of man-made chemicals, and even maintenance of Earth's atmospheric gases, simultaneity, the microbial communities potential for rapid growth and turnover, means the microbial community is a more sensitive reaction in the terrestrial ecosystem to external stress than plants and animals. Therefore, understanding microbial activities, biomass and its effect of climate change is essential to our understanding of evolution, community formation and sustainability of life on the earth and facilitate better management and protect of nature environments.
In this paper, soil samples of Qinghai-Tibet Plateau alpine grassland in Sanjiangyuan Nature Reserve was chosen to be studied, for revealing the composition of soil microbial activity and the biomass, and exploring the potential effects of climate change on microorganism. Four soil samples from this area with the nearly same texture, vegetation type and different altitude (3400-4200 m) were collected. The numbers and physiological functions of different type of microorganisms (bacteria, fungi, actinomycetes and some of microorganism), the microbial biomass (microbial biomass carbon and microbial biomass nitrogen) and the enzyme activities (cellulase, protease, urease, and sucrase) were analyzed. According to the analyse, some results were found. Firstly, the soil in this area was rich in organic carbon and the other nutrients; secondly, the sequence of the numbers of different microorganisms was bacteria>actinomycetes>fungi; thirdly, the sequence of the numbers of the main functional microbial was flora ammonifiers> aerobic azotobacteria> nitrate bacteria> nitrobacteria, fourthly, there were signicant differences among those samples in microbial biomass. Correlation analysis showed that the altitude had negative correlation with all the factors except nitrite bacteria, and the negative correlations were significant whether with the bacteria and ammonifiers or with the aerobic azotobacteria and nitrate bacteria. Therefore, the increasing temperature may have affected the activity of soil microorganisms in Qinghai-Tibet Plateau alpine grassland in Sanjiangyuan Nature Reserve significantly.