不同固沙区结皮中微生物生物量和数量的比较研究

Comparative Research on Microbial Biomass and Number in Soil Microbiotic Crust of Different Fixing Sand Dunes

沙地生态系统是温带干旱区、半干旱区的重要草地类型,沙地的稳定性是生态系统健康的重要条件。在中国科学院沙坡头沙漠试验研究站,笔者对不同程度固沙区结皮和流动沙丘表层中的微生物生物量和数量进行了比较研究。结果表明:自然和人工植被固沙区结皮及流沙表层的微生物数量分布不同,细菌数量比真菌和放线菌数量多数百倍,在所有微生物类群中,细菌数量最大,微生物总数的变化取决于好气性细菌数量的多少,但生物量却与之不同。在不同程度固沙区结皮中,微生物生物量大小依次排列为:自然植被区>1956年人工植被区>1964年人工植被区>1982年人工植被区>流沙区,微生物生物量在自然植被固沙区中最多,分别是1956年、1964年、1982年人工植被固沙区和流沙区的2 63、4 17、9 25和44 29倍,表明微生物生物量随人工植被的栽植年代增加而增大,在流动沙丘中最小,而菌丝生物量方面是1956年人工植被固沙区已与自然植被固沙区十分接近。微生物生物量和数量与沙丘固定程度、人工植被栽植年代、结皮厚度、苔藓种类等均呈正相关,人工植被栽植年代越长,结皮越厚、微生物生物量和数量也越大。在不同年代人工植被固沙区结皮中,微生物生物量和数量与相对稳定的自然植被固沙区相比,仍未达到稳定状态。

Comparing studies on biomass and number of microbial groups in the soil crust on artificial and natural vegetation fixed dunes as well as in mobile sand dune were conducted in Shapotou Desert Research and Experiment Station of Chinese Academy. Main conclusions are as follows: Microbial numbers in different soil microbiotic crusts were various. Bacterial number was the most in all groups of microorganism and more hundreds times than that of both fungi and actinomyces. The variation trend of total microbial number rests with the amount of aerophilic bacteria, but their biomass differs. Distribution order of microbial biomass in different sand dunes showed that natural vegetation fixed sand dune>artificial vegetation fixed dune of 1956>artificial vegetation fixed dune of 1964>artificial vegetation fixed dune of 1982>mobile sand dune. The total microbial biomass in natural vegetation fixed sand dune is 2.63 times of that in artificial vegetation fixed dune of 1956, 4.17 times of that of 1964, 9.25 times of that of 1982 and 44.29 times of that in mobile sand dune. The mycelial biomass in artificial vegetation fixed dune of 1956 almost equal to the biomass in natural vegetation fixed sand dune. Soil microbial biomass and number were positive related to the fixing degree of sand dunes or the years of artificial vegetation, the thickness of crust, the species of moss etc. The longer years of artificial vegetation, the thicker layer of the crust, the more amount of soil microorganism, the more coverage with herbage. Compared with the soil microbial biomass and number in steady natural vegetation fixed sand dune these different artificial vegetation fixed dunes have not reached the level of stability.