The seasonal pattern of soil microbial community structure in mesic low arctic tundra

Kate M. Buckeridge*, Samiran Banerjee, Steven D. Siciliano, Paul Grogan

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Soil microorganisms are critical to carbon and nutrient fluxes in terrestrial ecosystems. Understanding the annual pattern of soil microbial community structure and how it corresponds to soil nutrient availability and plant production is a fundamental first step towards being able to predict impacts of environmental change on ecosystem functioning. We investigated the composition, structure and nutrient stoichiometry of the soil microbial community in mesic arctic tundra on 9 sample dates in 6 months from winter to fall using phospholipid fatty acid analysis (PLFA), quantitative polymerase chain reaction (qPCR), epifluorescent microscopy and chloroform-fumigation-extraction (CFE). PLFA analysis indicates that the winter microbial community was fungal-dominated, cold-adapted and associated with high C, N and P in the soil solution and microbial biomass. The microscopy data suggest that both bacteria and fungi were active and growing in soils between -5 degrees C and 0 degrees C. A significant shift occurred in the PLFA data, qPCR patterns, microscopy and microbial biogeochemistiy after the thaw period, resulting in a distinct community that persisted through our spring, summer and fall sample dates, despite large changes in plant productivity. This shift was characterised by increasing relative abundances of certain bacteria (especially Gram +ves) as well as a decline in fungal biomass, and corresponded with decreasing C, N and P in the soil solution. The summer period of low substrate availability (plant-microbe competition) was associated with microbial indicators of nutritional stress. Overall, our results indicate that tundra microbial communities are clearly differentiated according to the changes in soil nutrient status and environmental conditions that occur between winter and post-thaw, and that those changes reflect functionally important adaptations to those conditions. (C) 2013 Elsevier Ltd. All rights reserved.

Original languageEnglish
Pages (from-to)338-347
Number of pages10
JournalSoil Biology and Biochemistry
Volume65
DOIs
Publication statusPublished - Oct 2013

Keywords

  • Microbial carbon
  • Microbial nitrogen
  • Microbial phosphorus
  • PLFA
  • qPCR
  • Epifluorescent microscopy
  • Arctic birch hummock tundra
  • Seasonal
  • Fungi
  • Bacteria
  • FATTY-ACID PROFILES
  • CARBON-DIOXIDE EXCHANGE
  • BIRCH HUMMOCK TUNDRA
  • 16S RIBOSOMAL-RNA
  • CLIMATE-CHANGE
  • LATE WINTER
  • BIOMASS
  • ECOSYSTEM
  • NITROGEN
  • BACTERIAL

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