Temperature sensitivity of organic matter decomposition in two boreal forest soil profiles

K. Karhu, H. Fritze, Mikko Tuomi, P. Vanhala, P. Spetz, V. Kitunen, J. Liski

Research output: Contribution to journalArticlepeer-review

107 Citations (Scopus)


Controversial conclusions from different studies suggest that the decomposition of old soil organic matter (SOM) is either more, less, or equally temperature sensitive compared to the younger SOM. Based on chemical kinetic theory, the decomposition of more recalcitrant materials should be more temperature sensitive, unless environmental factors limit decomposition. Here, we show results for boreal upland forest soils supporting this hypothesis. We detected differences in the temperature sensitivity 1) between soil layers varying in their decomposition stage and SOM quality, and 2) inside the layers during a 495 day laboratory incubation. Temperature sensitivity increased with increasing soil depth and decreasing SOM quality. In the organic layers, temperature sensitivity of decomposition increased during the early part of a 495 day laboratory incubation, after respiration rate and SOM quality had notably decreased. This indicates that decomposition of recalcitrant compounds was more temperature sensitive than that of the labile ones. Our results imply that Q10 values for total heterotrophic soil respiration determined from short-term laboratory incubations can either underestimate or overestimate the temperature sensitivity of SOM decomposition, depending on soil layer, initial labile carbon content and temperature range used for the measurements. Using Q10 values that ignore these factors in global climate models provides erroneous estimates on the effects of climate change on soil carbon storage.

Original languageEnglish
Pages (from-to)72-82
Number of pages11
JournalSoil Biology and Biochemistry
Issue number1
Early online date23 Oct 2009
Publication statusPublished - 1 Jan 2010


  • Decomposition
  • Incubation
  • Q10
  • Soil organic matter
  • Substrate availability
  • Temperature sensitivity


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