黄土丘陵区土壤生物结皮对土壤微生物分布特征的影响

Effect of soil biological crust on the distribution of soil microorganisms in the loess hilly region

通过对山西省偏关地区4种主要植被类型和撂荒地土壤生物结皮及下层土壤样本微生物的计数,研究不同植被状况下土壤生物结皮覆盖对土壤微生物生态分布特征的影响,探讨土壤生物结皮的生物学作用及影响土壤微生物数量的因子。结果表明：①在所有微生物类群中细菌数量最大,放线菌次之,真菌最少;②不同植被下土壤微生物数量差异显著（P〈0.05）,其中,撂荒地中的土壤微生物数量随着撂荒年限的增长而逐渐降低,油松林中土壤微生物数量则随林龄增长表现出了增长趋势;③微生物数量的垂直变化规律为：结皮层〉结皮下0-5 cm〉6-10 cm〉11-20 cm,细菌和微生物总数达到显著差异水平,放线菌和真菌也呈现明显下降趋势;④土壤微生物数量与土壤生物结皮的覆盖程度有关,有结皮土壤的微生物数量显著高于无结皮土壤的微生物数量,其中细菌数量以中等厚度结皮最高,放线菌和真菌数量以薄结皮最高。

Study was made on the effect of soil biological crust on the distribution of soil microorganisms in Pianguan area by using the statistics of the quantity of soil microorganisms of soil and soil biological crust under 4 kinds of main vegetation and abandoned land,so as to find out the biological effects of soil biological crust and influencing factors of the quantity of soil microorganisms.The results show that： ① In all the microbial groups,bacteria are the largest group and followed by actinomycetes while fungi are the least.② The quantity of soil microorganisms among different vegetations are significantly different（P0.05）,it decreased with the abandoned land fallow period and tend to increase with the pine planting years.③ Among different soil levels,crust layer is predominant,followed by 0-5 cm,6-10 cm the next,11-20 cm the least,bacteria and the total number of microorganisms are significantly different,actinomycetes and fungi decreased with the depth.④ The coverage of soil biological crust affects the quantity of soil microorganisms,and microbial content in soil with crust is obviously higher than that in soil without crust.The quantity of bacteria reach the peak value at soil with medium—thick crust,the maximum quantity of actinomycetes and fungi are located at soil with thin—layer crust.