Plant-microbial linkages underpin carbon sequestration in contrasting mountain tundra vegetation types

Konstantin Gavazov, Alberto Canarini, Vincent Jassey, Robert Mills, Andreas Richter, Maja Sundqvist, Maria Väisänen, Tom Walker, David Wardle, Ellen Dorrepaal

Research output: Contribution to journalArticlepeer-review

Abstract

Tundra ecosystems hold large stocks of soil organic matter (SOM), likely due to low temperatures limiting rates of microbial SOM decomposition more than those of SOM accumulation from plant primary productivity and microbial necromass inputs. Here we test the hypotheses that distinct tundra vegetation types and their carbon supply to characteristic rhizosphere microbes determine SOM cycling independent of temperature. In the subarctic Scandes, we used a three-way factorial design with paired heath and meadow vegetation at each of two elevations, and with each combination of vegetation type and elevation subjected during one growing season to either ambient light (i.e., ambient plant productivity), or 95% shading (i.e., reduced plant productivity). We assessed potential above- and belowground ecosystem linkages by uni- and multivariate analyses of variance, and structural equation modelling. We observed direct coupling between tundra vegetation type and microbial community composition and function, which underpinned the ecosystem's potential for SOM storage. Greater primary productivity at low elevation and ambient light supported higher microbial biomass and nitrogen immobilisation, with lower microbial mass-specific enzymatic activity and SOM humification. Congruently, larger SOM at lower elevation and in heath sustained fungal-dominated microbial communities, which were less substrate-limited, and invested less into enzymatic SOM mineralisation, owing to a greater carbon-use efficiency (CUE). Our results highlight the importance of tundra plant community characteristics (i.e., productivity and vegetation type), via their effects on soil microbial community size, structure and physiology, as essential drivers of SOM turnover. The here documented concerted patterns in above- and belowground ecosystem functioning is strongly supportive of using plant community characteristics as surrogates for assessing tundra carbon storage potential and its evolution under climate and vegetation changes.
Original languageEnglish
Article number108530
JournalSoil Biology and Biochemistry
Volume165
Early online date25 Dec 2021
DOIs
Publication statusPublished - 2022
MoEC publication typeA1 Journal article-refereed

Keywords

  • elevation gradient
  • Primary productivity
  • Above- and belowground interactions
  • C:N stoichiometry
  • Microbial physiology
  • Carbon use efficiency
  • Elevation gradient

Field of science

  • Geosciences
  • Environmental sciences

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