title: Vegetation-associated impacts on arctic tundra bacterial and microeukaryotic communities.
abstract: The Arctic is experiencing rapid vegetation changes, such as shrub and tree line expansion, due to climate warming, as well as increased wetland variability due to hydrological changes associated with permafrost thawing. These changes are of global concern because changes in vegetation may increase tundra soil biogeochemical processes that would significantly enhance atmospheric CO2 concentrations. Predicting the latter will at least partly depend on knowing the structure, functional activities, and distributions of soil microbes among the vegetation types across Arctic landscapes. Here we investigated the bacterial and microeukaryotic community structures in soils from the four principal low Arctic tundra vegetation types: wet sedge, birch hummock, tall birch, and dry heath. Sequencing of rRNA gene fragments indicated that the wet sedge and tall birch communities differed significantly from each other and from those associated with the other two dominant vegetation types. Distinct microbial communities were associated with soil pH, ammonium concentration, carbon/nitrogen (C/N) ratio, and moisture content. In soils with similar moisture contents and pHs (excluding wet sedge), bacterial, fungal, and total eukaryotic communities were correlated with the ammonium concentration, dissolved organic nitrogen (DON) content, and C/N ratio. Operational taxonomic unit (OTU) richness, Faith's phylogenetic diversity, and the Shannon species-level index (H') were generally lower in the tall birch soil than in soil from the other vegetation types, with pH being strongly correlated with bacterial richness and Faith's phylogenetic diversity. Together, these results suggest that Arctic soil feedback responses to climate change will be vegetation specific not just because of distinctive substrates and environmental characteristics but also, potentially, because of inherent differences in microbial community structure.
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, China University of Chinese Academy of Sciences, Beijing, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Shi
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, China University of Chinese Academy of Sciences, Beijing, China.
authors.forename: Xingjia
authors.initials: X
authors.lastname: Xiang
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, China University of Chinese Academy of Sciences, Beijing, China.
authors.forename: Congcong
authors.initials: C
authors.lastname: Shen
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, China hychu@issas.ac.cn groganp@queensu.ca.
authors.forename: Haiyan
authors.initials: H
authors.lastname: Chu
authors.affiliation: Department of Biology, University of Waterloo, West Waterloo, Ontario, Canada.
authors.forename: Josh D
authors.initials: JD
authors.lastname: Neufeld
authors.affiliation: Department of Biology, Queen's University, Kingston, Ontario, Canada.
authors.forename: Virginia K
authors.initials: VK
authors.lastname: Walker
authors.affiliation: Department of Biology, Queen's University, Kingston, Ontario, Canada hychu@issas.ac.cn groganp@queensu.ca.
authors.forename: Paul
authors.initials: P
authors.lastname: Grogan
mesh_terms: D001110:Arctic Regions; D001419:Bacteria / Q000145:classification*; D058448:Biota; D002244:Carbon / Q000032:analysis; D004275:DNA, Ribosomal / Q000235:genetics; D056890:Eukaryota / Q000145:classification*; D009584:Nitrogen / Q000032:analysis; D063245:Plant Development; D017422:Sequence Analysis, DNA; D012987:Soil / Q000737:chemistry; D012988:Soil Microbiology; D065929:Tundra; D014867:Water / Q000032:analysis
chemical_list: D004275:DNA, Ribosomal; D012987:Soil; D014867:Water; D002244:Carbon; D009584:Nitrogen