兰州市南山季节性土壤微生物特征及影响因素

为了探究不同季节和不同植被类型对土壤微生物分布的影响，以兰州市南山不同海拔的两种植被类型为研究对象，采用稀释涂布平板法测定了土壤微生物的季节动态变化特征.结果表明：研究区内细菌数量占微生物总数的96.22%~99.80%，远高于真菌和放线菌数量.土壤微生物类群随季节变化呈现明显差异，其总数整体表现为夏季最高，为89.22×10⁶cfu/g soil，分别是春、秋、冬季的12.02、3.28、2.74倍，其中夏季细菌数量最高，真菌与放线菌数量均在春季达到最大值.人工林样地土壤微生物数量略低于荒坡，环境因子中土壤含水量和有机碳含量高于荒坡.随着海拔的升高，pH值逐渐上升，土壤温度、有机碳与全氮含量逐渐下降，土壤微生物总数则呈现先减少后增加的趋势.相关分析表明，不同季节各微生物类群与环境因子的相关系数各有不同，春季放线菌与有机碳，秋季真菌与有机碳、全氮均呈极显著正相关（P<0.01）.冗余分析表明，环境因子中有机碳与第一物种轴的相关系数最高，为0.520，说明土壤有机碳含量是影响土壤微生物类群分布的主导因素.

Seasonal characteristics and influencing factors of soil microbial in Nanshan,Lanzhou

In order to explore the effects of different seasons and vegetation types on the distribution of soil microbes, two vegetation types were used as research objects at different altitudes in Nanshan of Lanzhou, the seasonal dynamics of soil microbes were measured by the dilution-coated plate. The results showed that the number of bacteria accounted for 96.22%~99.80% of the total number of microbes in the study area, far higher than the number of fungi and actinomycetes. The soil microorganism groups showed significant difference with the seasonal variation. The total number of soil microbes showed the highest in summer with, 89.22×10⁶cfu/g soil, which were 12.02, 3.28 and 2.74 times in spring, autumn and winter respectively. The number of bacteria was the highest in summer, and the number of fungi and actinomycetes reached the maximum in spring. The amount of soil microorganisms in the plantations was slightly lower than that on the barren slopes, and the soil water content and organic carbon contents were higher than those of the barren slopes. With the altitude increasing, pH increased gradually, soil temperature, organic carbon and total nitrogen decreased gradually, and the total number of soil microorganisms decreased firstly and then increased. Correlation analysis showed that the correlation coefficients of microbial groups and environmental factors were different in different seasons. In spring, there was significant positive correlation between actinomycetes and organic carbon, and fungi and soil organic carbon and total nitrogen had a significant positive correlation (P<0.01) in autumn. Redundancy analysis showed that the highest correlation coefficient between organic carbon and the first species axis was 0.520, indicating that soil organic carbon content was the dominant factor affecting the distribution of soil microbial groups.