Temperature sensitivity of soil carbon fractions in boreal forest soil

Kristiina Karhu, Hannu Fritze, Kai Hämäläinen, Pekka Vanhala, Högne Jungner, Markku Oinonen, Eloni Sonninen, Mikko Tuomi, Peter Spetz, Veikko Kitunen, Jari Liski

Research output: Contribution to journalArticlepeer-review

75 Citations (Scopus)


Feedback to climate warming from the carbon balance of terrestrial ecosystems depends critically on the temperature sensitivity of soil organic carbon (SOC) decomposition. Still, the temperature sensitivity is not known for the majority of the SOC, which is tens or hundreds of years old. This old fraction is paradoxically concluded to be more, less, or equally sensitive compared to the younger fraction. Here, we present results that explain these inconsistencies. We show that the temperature sensitivity of decomposition increases remarkably from the youngest annually cycling fraction (Qio < 2) to a decadally cycling one (Qio = 4.2-6.9) but decreases again to a centennially cycling fraction (Qio = 2.4-2.8) in boreal forest soil. Compared to the method used for current global estimates (temperature sensitivity of all SOC equal to that of the total heterotrophic soil respiration), the soils studied will lose 30-45% more carbon in response to climate warming during the next few decades, if there is no change in carbon input. Carbon input, derivative of plant productivity, would have to increase by 100-120%, as compared to the earlier estimated 70-80%), in order to compensate for the accelerated decomposition.

Original languageEnglish
Pages (from-to)370-376
Number of pages7
JournalFungal Ecology
Issue number2
Publication statusPublished - 1 Feb 2010


  • Boreal forest
  • Decomposition
  • Finland
  • Soil organic carbon
  • Soil organic matter
  • Temperature sensitivity


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