关键词: 沙坡头, 人工植被, 结皮, 微生物生物量, 微生物数量

Abstract: 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.

Key words: Shapotou, artificial vegetation, microbiotic crust, microbial biomass, microbial number