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为探明半干旱沙区生物结皮中微生物分布特征,对毛乌素沙地南缘沙丘生物结皮中微生物数量进行了测定。结果表明:微生物总数从丘顶到丘间地呈递增趋势,除丘顶与迎风坡、迎风坡与背风坡结皮层微生物总数差异不显著外,其他各地貌部位结皮层微生物数量之间差异显著。同一地貌部位结皮层、0～5和5～10cm土层微生物垂直分布有变化,其变化规律为:除迎风坡放线菌数量呈先增加后递减、迎风坡微生物总数、细菌、真菌和丘顶真菌数量随剖面的加深呈递减外,其他各地貌部位微生物数量均呈先降低,后增加的趋势。微生物类群的组成表现为细菌最多,放线菌次之,真菌最少。在丘间地细菌所占微生物总数的比例与丘顶相比有所增加,而放线菌和真菌的比例有所减少。结皮下0～5和5～10cm土层微生物分布与土壤含水量的变化同步,说明土壤水分可能是影响微生物垂直分布的重要因子。
In order to find out the distribution characteristics of microorganisms in the biological crusts in the semi-arid sand area, the number of microbes in the biological crusts of the dunes in the southern margin of the Mu Us Sandland was determined. The results showed that the total number of microorganisms increased from the top of the hill to the mound, with no significant difference in the total number of microorganisms in the crusts of the topography except for the top of the hill and the windward slope, and the total number of microbes in the cortex of the windward slope and the lee slope. In the same landform crust, the vertical distribution of microorganisms in 0 ~ 5 and 5 ~ 10cm soil layers changed. The change law was that the number of actinomycetes increased first and then decreased, the total number of microbes on windward slope, bacteria, fungi and hilltop The number of fungi decreased with the deepening of the profile, while the number of other microbes in each topography decreased first and then increased. The composition of microbial groups showed the most bacteria, followed by actinomycetes, the least fungi. The proportion of bacteria in the mound between the total number of microorganisms increased compared with the top of the hill, while the proportion of actinomycetes and fungi decreased. The distribution of microorganisms in 0 ~ 5 and 5 ~ 10 cm soil layers under the crust was synchronous with the change of soil water content, indicating that soil moisture may be an important factor affecting the vertical distribution of microorganisms.