天祝高寒草地不同扰动生境土壤三大类微生物数量动态研究

Dynamics of soil microbial population under disturbance in Tianzhu Alpine grassland

采用平板表面涂抹法和稀释法对天祝高寒草地5种不同干扰生境（围栏内、围栏外、多年生草地、一年生草地和鼠丘地）土壤三大类微生物（真菌、细菌和放线菌2数量的时空动态进行了测定。结果表明，1）不同空间层次草地土壤三大类微生物数量变化均较大．0～20cm土层的数量均大于20～40cm，一般0～20cm土层的数量为20～40cm的2～7倍；2）不同时间三大类微生物数量变化虽然各有特点，但总趋势为：0～20cm土层的数量表现出明显的时间差异性，20～40cm未表现出时间动态或时间动态很弱；3）不同扰动生境草地土壤三大类微生物总数量差异较大．为8．47×10^6～16．22×10^6cfu／g，其大小为：一年生草地〉围栏内草地≥多年生草地〉鼠丘地〉围栏外草地。三大类微生物中，细菌数量最大，放线菌次之，真菌最小，分别占微生物总数的82．29％～86．09％，13．91％～17．71％和0．017％～0．023％。

The number and distribution of soil microorganisms （fungi, actinomycete and bacteria） in alpine grassland under different disturbance in Tianzhu were investigated and analyzed by using plate colony count and MPN methods. The results obtained are as follows： 1）The number of soil microorganisms greatly varies with soil depth. The number is much higher within 0-20 cm than that within 20-40 cm （2-7 times） ; 2）The number of soil microorganisms shows a seasonal pattern, that is, significant seasonal changes were observed within 0-20 cm （the highest in August, followed by july, the lowest in September） ; the same trend shows within 20 -40 cm, but the variation range is very small; 3）Total number of microorganism is much different among different disturbed habitant and it ranges from 8.47×10^6 cfu/g dry soil to 16.22×10^6 cfu/g dry soil. The order is that annual artificial grassland〉 fenced grassland≥perennial artificial grassland〉soil pile （in rodents damaged grass land）〉un-fenced grassland. Among the microorganisms, the number of bacteria is the highest （82.29%-86.09%）, then followed by actinomycetes （13.91%-17.71%）, fungi is lowest （0.017%-0. 023%）. Bacteria and actinomycete account for 99.9% of the total.