Abstract
The wetlands of the Qinghai-Tibetan Plateau are believed to play an important role in global nutrient cycling, but the composition and diversity of microorganisms in this ecosystem are poorly characterized. An understanding of the effects of geography and microtopography on microbial populations will provide clues to the underlying mechanisms that structure microbial communities. In this study, we used pyrosequencing-based analysis of 16S rRNA gene sequences to assess and compare the composition of soil microbial communities present in hummock and hollow soils from three wetlands (Dangxiong, Hongyuan and Maduo) on the Qinghai-Tibetan Plateau, the world’s highest plateau. A total of 36 bacterial phyla were detected. Proteobacteria (34.5% average relative abundance), Actinobacteria (17.3%) and Bacteroidetes (11%) had the highest relative abundances across all sites. Chloroflexi, Acidobacteria, Verrucomicrobia, Firmicutes, and Planctomycetes were also relatively abundant (1–10%). In addition, archaeal sequences belonging to Euryarchaea, Crenarchaea and Thaumarchaea were detected. Alphaproteobacteria sequences, especially of the order Rhodospirillales, were significantly more abundant in Maduo than Hongyuan and Dangxiong wetlands. Compared with Hongyuan soils, Dangxiong and Maduo had significantly higher relative abundances of Gammaproteobacteria sequences (mainly order Xanthomonadales). Hongyuan wetland had a relatively high abundance of methanogens (mainly genera Methanobacterium, Methanosarcina and Methanosaeta) and methanotrophs (mainly Methylocystis) compared with the other two wetlands. Principal coordinate analysis (PCoA) indicated that the microbial community structure differed between locations and microtopographies and canonical correspondence analysis indicated an association between microbial community structure and soil properties or geography. These insights into the microbial community structure and the main controlling factors in wetlands of the Qinghai-Tibetan Plateau provide a valuable background for further studies on biogeochemical processes in this distinct ecosystem.
Highlights
Soil microbial communities in wetland systems play an important role in biogeochemical cycles and are crucial to the functions of wetland systems [1]
Site description and soil sampling Three Sedge-dominant wetlands located on the Qinghai-Tibetan Plateau (Figure S1) and characterized by hummockhollow microtopography were chosen for the study
Microbial communities of three Sedge-dominated natural wetlands in the Qinghai-Tibetan Plateau were investigated by 454-pyrosequencing in this study
Summary
Soil microbial communities in wetland systems play an important role in biogeochemical cycles and are crucial to the functions of wetland systems [1]. In contrast to boreal wetlands located at high latitude regions, wetlands in this region are at low latitude and high altitude They have distinguishing features of hummock-hollow microtopography and Sedge-dominated vegetation [6]. Wetlands on the QinghaiTibetan Plateau are very sensitive to climate change and they play a vital role in terrestrial carbon storage [7]. These wetlands provide many important ecological services, such as ensuring the productivity of rangelands and providing grazing ground for thousands of livestock animals. A few cultivationindependent studies using denaturing gradient gel electrophoresis (DGGE) fingerprinting and limited clone library construction have been carried-out to assess the bacterial diversity in wetlands of this region [14]
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