Ecological Distribution Of Soil Microorganism Of Alpine Grassland In Eastern Qilian Mountains And Identification Of The Dominant Microbes

In this paper, four different representative grassland types in Eastern Qilian Mountains were selected to be experimental samples. They were Polygonum meadow, Grass steppe, Swamp meadow and Kobresia meadow. Systematic studies on the ecological distribution characteristics of soil microorganism and the different microbial physiological functional groups were conducted, such as the quantity seasonal dynamics, vertical dynamics, horizonal dynamics. And dominant species'identification and distribution characheristics were studied as well. All reseaches were based on the methods of traditional separation methods and microbial molecular ecology. The main research results were as follows:1. The distribution characteristis of soil bacteria, fungi and actinomycetesThe ecological distribution characteristics of soil microorganisms were as follows: (1)Seasonal dynamics: The seasonal changing trend of the total microorganisms was that the microbial quantity was fewest in May,then increased as atomosphere became warmer, and reached peak in July and September respectly,decreased in November; The quantities change trend of different soil microbial species is different, the quantities of bacteria and fungi were most in July to September and the quantity of actinomycetes was most in November.(2)Horizonal dynamics: The quantity of microorganisms in Grass steppe was the highest. The second was Kobresia meadow. The third was Polygonum viviparum L. meadow. And the lowest was Swamp meadow; The quantities of bacteria, fungi and actinomycetes in Grassland steppe and Kobresia meadow all had significant differences(p<0.01). (3) Vertical dynamics: The amount of microorganism in 0~10cm soil layer was significantly much more than that of 10~20cm soil layer, microbial quantities decreased as the soil layer was deeper, they had the same tendency with soil microorganisms.These findings demonstrate that more soil microorganisms distributed in the top layer, where secretion from densely distributed grass roots together with accumulated leaves and sticks were transformed into nutrients, and offer a favorable humidity, warmth and air permeability, favorable for the growth and proliferation of soil microorganisms. (4) Proportion: Bacteria and actinomycetes were significantly dominant in alpine grassland soil, and the proportion of bacteria and actinomycetes was above 99% in each month of plant growing stage, while their proportions were almost equal to each other. however, the proportion of fungi was only 0.09-0.72% all the year round; The proportion of bacteria reached peak in July(56.73～76.59%),and got down the low in November(23.11%-37.59%). On the contrary, the proportion of actinomyces was reached peak in November(62.14-76.69%), it was obviously higher than bacteria.The difference of ecological environments caused the difference of the microbial proportion distribution.