黄土高原不同植被坡地土壤微生物区系特征

Microbial populations in different vegetations in sloping field on the Loess Plateau

应用稀释平板法对黄土高原不同植被覆盖下坡地土壤0～5 cm和5～20 cm土层的细菌、真菌和放线菌的分布特征进行了研究;结果表明：（1）该区域不同植被下土壤中细菌、真菌和放线菌总体比较丰富,数量差异较大,柠条土壤中微生物数量最多,苜蓿地中的最少。同一植被下各类菌群数量排序为细菌〉放线菌〉真菌。（2）放线菌和真菌随土层深度的增加而呈明显的减少趋势,而细菌的不明显。（3）天然荒坡的微生物数量高于人工草地的,人工灌木林微生物数量高于人工乔木林的,人工乔草复生果树林的微生物数量高于人工纯生乔木林、纯生草地和纯生果树林的。

Microbial populations at different soil depths in the different vegetation soils of the Mizhi county on the Loess Plateau were studied. The results showed that （ 1 ） in this region, the amount of soil microbes was abundant and the proportion of Caragana korshinskii was much larger than others. It was least under Medicago sativa L. However, the different proportions of bacteria, fungi and actinomycetes in a plot was obvious and in the order ： bacteria 〉 actinomycetes 〉 fungi. （2） The quantity of aetinomycetes and fungi clearly decreased with the soil depth, however this was not obvious for bacteria. （3） The quantity of microbes under the naturally vegetated slope was larger than under than annual Medicago sativa L. grassland. The quantity of microbes under the bush vegetation- Caragana korshinskii- was more than under tree forest- dominated by Prunus armeniaca, Robinia Pseudoacacia, Platrhadus orientalis and Ziziphus jujube. The quantity of microbes under fruit tree plantations, （Prunus armeniaca） , which also supported grass, was greater than under the forest, Platrhadus orientalis, and Robinia pseudoacacia, pure grassland, Medicago sativa L. and fruit tree plantations of Ziziphus jujube.