Moth outbreaks reduce decomposition in subarctic forest soils

Hans Sanden, Mathias Mayer, Sari Stark, Sanden Taru, Lars Ola Nilsson, Jane Uhd Jepsen, Piippa Riitta Wäli, Boris Rewald

Research output: Contribution to journalArticleScientificpeer-review

12 Citations (Scopus)


Tree mortality from insect infestations can significantly reduce carbon storage in forest soils. In subarctic birch forests (Betula pubescens), ecosystem C cycling is largely affected by recurrent outbreaks of defoliating geometrid moths (Epirrita autumnata, Operophtera brumata). Here, we show that soil C stocks in birch forests across Fennoscandia did not change up to 8 years after moth outbreaks. We found that a decrease in woody fine roots was accompanied by a lower soil CO2 efflux rate and a higher soil N availability following moth outbreaks. We suggest that a high N availability and less ectomycorrhiza likely contributed to lowered heterotrophic respiration and soil enzymatic activity. Based on proxies for decomposition (heterotrophic respiration, phenol oxidase potential activity), we conclude that a decrease in decomposition is a prime cause why soil C stocks of mountain birch forest ecosystems have not changed after moth outbreaks. Compared to disturbed temperate and boreal forests, a CO2-related positive feedback of forest disturbance on climate change might therefore be smaller in subarctic regions.
Original languageEnglish
Publication statusE-pub ahead of print - 14 May 2019
MoEC publication typeA1 Journal article-refereed

Field of science

  • Ecology, evolutionary biology
  • Plant biology, microbiology, virology


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