Altered carbon turnover processes and microbiomes in soils under long-term extremely high CO2 exposure

Nat Microbiol. 2016 Jan 27;1:15025. doi: 10.1038/nmicrobiol.2015.25.

Abstract

There is only limited understanding of the impact of high p(CO2) on soil biomes. We have studied a floodplain wetland where long-term emanations of temperate volcanic CO2 (mofettes) are associated with accumulation of carbon from the Earth's mantle. With an integrated approach using isotope geochemistry, soil activity measurements and multi-omics analyses, we demonstrate that high (nearly pure) CO2 concentrations have strongly affected pathways of carbon production and decomposition and therefore carbon turnover. In particular, a promotion of dark CO2 fixation significantly increased the input of geogenic carbon in the mofette when compared to a reference wetland soil exposed to normal levels of CO2. Radiocarbon analysis revealed that high quantities of mofette soil carbon originated from the assimilation of geogenic CO2 (up to 67%) via plant primary production and subsurface CO2 fixation. However, the preservation and accumulation of almost undegraded organic material appeared to be facilitated by the permanent exclusion of meso- to macroscopic eukaryotes and associated physical and/or ecological traits rather than an impaired biochemical potential for soil organic matter decomposition. Our study shows how CO2-induced changes in diversity and functions of the soil community can foster an unusual biogeochemical profile.

MeSH terms

  • Carbon Cycle
  • Carbon Dioxide / metabolism*
  • Eukaryota / classification
  • Eukaryota / metabolism
  • Microbiota / drug effects*
  • Prokaryotic Cells / classification
  • Prokaryotic Cells / metabolism
  • Soil Microbiology*
  • Wetlands

Substances

  • Carbon Dioxide