三江源地区高寒草原土壤微生物活性和微生物量

为了揭示青藏高原高寒草地土壤微生物活性和微生物量碳、氮情况，同时探讨气候变化对土壤微生物的影响，以青藏高原腹地三江源自然保护区高寒草原土壤为研究对象，选择土壤质地、植被类型基本一致，海拔高度不同（3400—4200m）的4个样地，分析测定了土壤微生物（细菌、真菌、放线菌和部分生理功能微生物群）数量、土壤微生物量（碳、氮）、土壤酶（纤维素酶、蛋白酶、脲酶用、蔗糖酶）活性。结果表明：研究区域均含有较丰富的土壤有机碳和养分，微生物数量多少为细菌>放线菌>真菌，主要功能微生物菌群数量为氨化细菌>好气性固氮菌>硝化细菌>亚硝化细菌，样地间的微生物生物量碳、氮含量差异显著。相关性分析表明，除与亚硝酸细菌具有弱正相关性外，海拔高度与其它因子均具有负相关性，其中与细菌和氨化细菌具有极显著负相关性，与好气性固氮菌和硝酸细菌具有显著负相关性。因此，温度的升高可能明显的影响了三江源地区高寒草原的土壤微生物活性。

The soil microbial activities and microbial biomass in Sanjiangyuan Alpine glassland

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.