青藏高原北麓河地区荒漠草原土壤细菌对热融滑塌的响应

The response of soil bacteria to thaw slump in a desert steppe in Beiluhe area, Qinghai-Tibet Plateau

多年冻土区地下冰融化造成的热融滑塌会对土壤理化性质产生一系列影响,进而影响微生物群落结构,但目前热融滑塌对荒漠草原区土壤微生物的影响还不清楚。利用Illumina测序方法,以青藏高原北麓河多年冻土区发生热融滑塌的荒漠草原为研究对象,对3种微地貌(对照区、滑塌区、沉降区)下的土壤细菌展开研究,分析了细菌群落结构及其与环境因子间的关系。结果显示滑塌区和沉降区有机碳含量显著低于对照区,滑塌区土壤含水量最高;放线菌门、变形菌门、绿弯菌门和酸杆菌门是3种微地貌下的优势菌群,对照区细菌群落丰富度显著低于滑塌区。Mantel检验表明,细菌群落结构与土壤理化性质间无显著相关性;非度量多维尺度分析(NMDS)表明,微生物群落结构在3种微地貌下显著不同。研究结果表明,在荒漠草原区,热融滑塌会改变土壤理化性质,影响细菌特定门的微生物相对丰度,但对门水平的整体群落结构影响不显著。

Thaw slumping is caused by the melting of ground ice in permafrost,which may impact soil physical and chemical properties and thus affect the microbial community structures. However,the effect of thaw slump on the soil microbes under desert steppe remains unknown. In this study,the Illumina sequencing method was used to examine the bacterial communities in micro-topographies,which are under the land cover of desert steppe in permafrost on the central Qinghai-Tibet Plateau. Three micro-morphologies(control,collapsing,slumped)were defined,and the relationships among bacterial community and environmental factors were investigated. The results showed that soil organic carbon contents in the collapsing and slumped areas were significantly lower than that in the control areas,and soil water contents were highest in the collapsing areas. For all the three types of soil,the most abundant bacterial phyla were Actinobacteria,Proteobacteria,Chloroflexi and Acidobacteria. Bacterial richness in collapsing area was higher than that in control area. Mantel test had found no significant relationships between bacterial community structures and soil physico-chemical properties. The Non-metric multidimensional scaling(NMDS)results showed that the bacterial community structure was significantly different among the three micro-morphologies. The results showed that in the desert steppe area,thaw slump changes the physical and chemical variables of the soil,further affects the relative abundance of specific bacteria at phylum level,while has no significant effect on the overall bacterial community structures.