冻融循环对青藏高原腹地不同生态系统土壤细菌群落结构的影响

Effect of Freeze-Thaw Cycles on the Soil Bacterial Communities in Different Ecosystem Soils in the Tibetan Plateau

通过构建16SrRNA基因克隆文库,研究了冻融循环对青藏高原腹地北麓河的高寒沼泽草甸和高寒沙化草原两种不同生态系统土壤细菌群落结构的影响.结果表明:α-、β-、γ-和δ-变形菌门(α-、β-、γ-和δ-Proteobacteria)、酸杆菌门(Acidobacteria)、放线菌门(Actinobacteria)、拟杆菌门(Bacte-roidetes)和浮霉菌门(Planctomycetes)为两个生态系统土壤共有的细菌类群,其中,变形菌门、酸杆菌门及浮霉菌门细菌为研究区域优势菌,而厚壁菌门(Firmicutes)为高寒沼泽草甸土壤所特有,疣微菌门(Verrucomicrobia)和绿弯菌门(Chloroflexi)细菌是高寒沙化草原土壤特有的细菌类群,表明青藏高原腹地两种生态系统土壤具有丰富的细菌多样性.冻融循环会降低区域土壤的细菌多样性,随冻融循环,高寒沼泽草甸和高寒沙化草原生态系统土壤放线菌门丰度均呈现下降趋势,但大部分细菌随冻融循环的变化在两种生态类型中呈现不同的变化规律,结果说明冻融循环对于不同生态系统土壤细菌群落结构的影响既存在相似性,也存在着较大的差异.

In this paper,the effects of freeze-thaw cycle on the structure of soil bacterial communities in the soils of two ecosystems in the interior of the Tibetan Plateau are studied by the method of 16S rDNA clone libraries.The soil samples were taken from two ecosystems： alpine-cold swamp meadow and alpine sandy grassland in the Beiluhe located in the plateau.It is found that α-,β-,γ-,δ-Proteobacteria,Cidobacteria,Actinobacteria,Bacteroidetes,and Planctomycetes are the common bacterial groups in the soils of the two ecosystems.Among them,Proteobacteria,Acidobacteria and Planctomycetes are the predominant ones.Firmicutes is the one that only exists in the alpine-cold swamp meadow soils,while Verrucomicrobia and Chloroflexi are the two that only exist in the alpine sandy grassland soils.Phylogenetic analysis has revealed the rich diversity of bacteria,which decreases with freeze-thaw cycle.Furthermore,Actinobacteria decreases with freeze-thaw cycle in the two ecosystem soils.However,majority of the bacteria shows different variation in the two ecosystems.It is demonstrated that the effect of freeze-thaw cycles on soil bacterial communities has similarity in the two ecosystem soils,but great discrepancy also shows in some bacterial groups.