title: Biogeographic patterns of soil diazotrophic communities across six forests in North America.
abstract: Soil diazotrophs play important roles in ecosystem functioning by converting atmospheric N2 into biologically available ammonium. However, the diversity and distribution of soil diazotrophic communities in different forests and whether they follow biogeographic patterns similar to macroorganisms still remain unclear. By sequencing nifH gene amplicons, we surveyed the diversity, structure and biogeographic patterns of soil diazotrophic communities across six North American forests (126 nested samples). Our results showed that each forest harboured markedly different soil diazotrophic communities and that these communities followed traditional biogeographic patterns similar to plant and animal communities, including the taxa-area relationship (TAR) and latitudinal diversity gradient. Significantly higher community diversity and lower microbial spatial turnover rates (i.e. z-values) were found for rainforests (~0.06) than temperate forests (~0.1). The gradient pattern of TARs and community diversity was strongly correlated (r(2)  > 0.5) with latitude, annual mean temperature, plant species richness and precipitation, and weakly correlated (r(2)  < 0.25) with pH and soil moisture. This study suggests that even microbial subcommunities (e.g. soil diazotrophs) follow general biogeographic patterns (e.g. TAR, latitudinal diversity gradient), and indicates that the metabolic theory of ecology and habitat heterogeneity may be the major underlying ecological mechanisms shaping the biogeographic patterns of soil diazotrophic communities.
authors.affiliation: Department of Marine Sciences, Ocean College, Zhejiang University, Zhejiang, 310058, China.|Department of Microbiology and Plant Biology, Institute for Environmental Genomics, University of Oklahoma, Norman, OK, 73019, USA.
authors.forename: Qichao
authors.initials: Q
authors.lastname: Tu
authors.affiliation: Research Center for Eco-Environmental Science, Chinese Academy of Sciences, Beijing, 100085, China.
authors.forename: Ye
authors.initials: Y
authors.lastname: Deng
authors.affiliation: Department of Microbiology and Plant Biology, Institute for Environmental Genomics, University of Oklahoma, Norman, OK, 73019, USA.
authors.forename: Qingyun
authors.initials: Q
authors.lastname: Yan
authors.affiliation: Department of Microbiology and Plant Biology, Institute for Environmental Genomics, University of Oklahoma, Norman, OK, 73019, USA.
authors.forename: Lina
authors.initials: L
authors.lastname: Shen
authors.affiliation: Department of Marine Sciences, Ocean College, Zhejiang University, Zhejiang, 310058, China.
authors.forename: Lu
authors.initials: L
authors.lastname: Lin
authors.affiliation: Department of Microbiology and Plant Biology, Institute for Environmental Genomics, University of Oklahoma, Norman, OK, 73019, USA.
authors.forename: Zhili
authors.initials: Z
authors.lastname: He
authors.affiliation: Department of Microbiology and Plant Biology, Institute for Environmental Genomics, University of Oklahoma, Norman, OK, 73019, USA.
authors.forename: Liyou
authors.initials: L
authors.lastname: Wu
authors.affiliation: Department of Microbiology and Plant Biology, Institute for Environmental Genomics, University of Oklahoma, Norman, OK, 73019, USA.
authors.forename: Joy D
authors.initials: JD
authors.lastname: Van Nostrand
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721, USA.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Buzzard
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721, USA.|Earth and Environmental Sciences Division, Los Alamos National Laboratory, MS J495, Los Alamos, NM 87545, USA.
authors.forename: Sean T
authors.initials: ST
authors.lastname: Michaletz
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721, USA.|The Santa Fe Institute, 1399 Hyde Park Rd, Santa Fe, NM, 87501, USA.
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Enquist
authors.affiliation: Department of Biology, EEB Graduate Program, University of Oklahoma, Norman, OK, 73019, USA.
authors.forename: Michael D
authors.identifier: 0000-0001-9080-0834
authors.initials: MD
authors.lastname: Weiser
authors.affiliation: Department of Biology, EEB Graduate Program, University of Oklahoma, Norman, OK, 73019, USA.|Smithsonian Tropical Research Institute, Balboa, 0843-03092, Republic of Panama.
authors.forename: Michael
authors.initials: M
authors.lastname: Kaspari
authors.affiliation: Department of Biology, University of New Mexico, Albuquerque, NM, 87131, USA.
authors.forename: Robert B
authors.initials: RB
authors.lastname: Waide
authors.affiliation: Department of Biology, University of New Mexico, Albuquerque, NM, 87131, USA.
authors.forename: James H
authors.initials: JH
authors.lastname: Brown
authors.affiliation: Department of Microbiology and Plant Biology, Institute for Environmental Genomics, University of Oklahoma, Norman, OK, 73019, USA.|State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, China.|Earth Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94270, USA.
authors.forename: Jizhong
authors.initials: J
authors.lastname: Zhou
mesh_terms: D001419:Bacteria / Q000145:classification; D044822:Biodiversity; D002244:Carbon / Q000032:analysis; D065928:Forests; D005798:Genes, Bacterial; D009584:Nitrogen / Q000032:analysis; D009656:North America; D065947:Rainforest; D012987:Soil / Q000737:chemistry; D012988:Soil Microbiology
chemical_list: D012987:Soil; D002244:Carbon; D009584:Nitrogen
keywords: biogeography; diversity gradients; nifH; soil diazotrophs; taxa-area relationship