title: Vertical distribution of the soil microbiota along a successional gradient in a glacier forefield.
abstract: Spatial patterns of microbial communities have been extensively surveyed in well-developed soils, but few studies investigated the vertical distribution of micro-organisms in newly developed soils after glacier retreat. We used 454-pyrosequencing to assess whether bacterial and fungal community structures differed between stages of soil development (SSD) characterized by an increasing vegetation cover from barren (vegetation cover: 0%/age: 10 years), sparsely vegetated (13%/60 years), transient (60%/80 years) to vegetated (95%/110 years) and depths (surface, 5 and 20 cm) along the Damma glacier forefield (Switzerland). The SSD significantly influenced the bacterial and fungal communities. Based on indicator species analyses, metabolically versatile bacteria (e.g. Geobacter) and psychrophilic yeasts (e.g. Mrakia) characterized the barren soils. Vegetated soils with higher C, N and root biomass consisted of bacteria able to degrade complex organic compounds (e.g. Candidatus Solibacter), lignocellulolytic Ascomycota (e.g. Geoglossum) and ectomycorrhizal Basidiomycota (e.g. Laccaria). Soil depth only influenced bacterial and fungal communities in barren and sparsely vegetated soils. These changes were partly due to more silt and higher soil moisture in the surface. In both soil ages, the surface was characterized by OTUs affiliated to Phormidium and Sphingobacteriales. In lower depths, however, bacterial and fungal communities differed between SSD. Lower depths of sparsely vegetated soils consisted of OTUs affiliated to Acidobacteria and Geoglossum, whereas depths of barren soils were characterized by OTUs related to Gemmatimonadetes. Overall, plant establishment drives the soil microbiota along the successional gradient but does not influence the vertical distribution of microbiota in recently deglaciated soils.
authors.affiliation: Forest Soils and Biogeochemistry, Swiss Federal Research Institute WSL, 8903, Birmensdorf, Switzerland.
authors.forename: Thomas
authors.initials: T
authors.lastname: Rime
authors.forename: Martin
authors.initials: M
authors.lastname: Hartmann
authors.forename: Ivano
authors.initials: I
authors.lastname: Brunner
authors.forename: Franco
authors.initials: F
authors.lastname: Widmer
authors.forename: Josef
authors.initials: J
authors.lastname: Zeyer
authors.forename: Beat
authors.initials: B
authors.lastname: Frey
mesh_terms: D001419:Bacteria / Q000145:classification; D018533:Biomass; D021903:DNA, Ribosomal Spacer / Q000235:genetics; D017753:Ecosystem; D005658:Fungi / Q000145:classification; D046448:Ice Cover / Q000382:microbiology*; D064307:Microbiota; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D012987:Soil; D012988:Soil Microbiology; D062206:Spatial Analysis; D013557:Switzerland
chemical_list: D021903:DNA, Ribosomal Spacer; D012336:RNA, Ribosomal, 16S; D012987:Soil
keywords: 454-pyrosequencing; DNA metabarcoding; glacier retreat; indicator species analysis; soil formation; vertical distribution