Heat wave-induced microbial thermal trait adaptation and its reversal in the Subarctic

Dániel Tájmel*, Carla Cruz-Paredes, Johannes Rousk

*Corresponding author

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review


Climate change predictions suggest that arctic and subarctic ecosystems will be particularly affected by rising temperatures and extreme weather events, including severe heat waves. Temperature is one of the most important environmental factors controlling and regulating microbial decomposition in soils; therefore, it is critical to understand its impact on soil microorganisms and their feedback to climate warming. We conducted a warming experiment in a subarctic birch forest in North Sweden to test the effects of summer heat waves on the thermal trait distributions that define the temperature dependences for microbial growth and respiration. We also determined the microbial temperature dependences 10 and 12 months after the heat wave simulation had ended to investigate the persistence of the thermal trait shifts. As a result of warming, the bacterial growth temperature dependence shifted to become warm-adapted, with a similar trend for fungal growth. For respiration, there was no shift in the temperature dependence. The shifts in thermal traits were not accompanied by changes in α- or β-diversity of the microbial community. Warming increased the fungal-to-bacterial growth ratio by 33% and decreased the microbial carbon use efficiency by 35%, and both these effects were caused by the reduction in moisture the warming treatments caused, while there was no evidence that substrate depletion had altered microbial processes. The warm-shifted bacterial thermal traits were partially restored within one winter but only fully recovered to match ambient conditions after 1 year. To conclude, a summer heat wave in the Subarctic resulted in (i) shifts in microbial thermal trait distributions; (ii) lower microbial process rates caused by decreased moisture, not substrate depletion; and (iii) no detectable link between the microbial thermal trait shifts and community composition changes.
TidsskriftGlobal Change Biology
Udgave nummer1
StatusUdgivet - jan. 2024
Udgivet eksterntJa

Bibliografisk note

Funding Information:
We thank the Swedish Polar Research Secretariat and SITES for the support of the work done at the Abisko Scientific Research Station. We also thank Lettice C. Hicks and Albert C. Brangarí for their help with setting up the warming experiment. SITES is supported by the Swedish Research Council (grant no. 4.3‐2021‐00164). This work was supported by grants from the Danmarks Frie Forskningsfond (DFF, grant no. 9036‐00004B), the Swedish Research Council Vetenskapsrådet (VR, grant no. 2020‐04083) and the Knut and Alice Wallenberg Foundation (grant no. KAW 2022.0175). The research contributes to the strategic research area Biodiversity and Ecosystems in a Changing Climate (BECC) at Lund University.


  • carbon use efficiency
  • extreme weather event
  • microbial community
  • microbial growth
  • microbial respiration
  • soil warming
  • summer heat waves
  • temperature dependence

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