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Biogeosciences An interactive open-access journal of the European Geosciences Union
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Volume 12, issue 18
Biogeosciences, 12, 5353–5363, 2015
https://doi.org/10.5194/bg-12-5353-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.

Special issue: Interactions between climate change and the Cryosphere: SVALI,...

Biogeosciences, 12, 5353–5363, 2015
https://doi.org/10.5194/bg-12-5353-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 17 Sep 2015

Research article | 17 Sep 2015

Tree water relations can trigger monoterpene emissions from Scots pine stems during spring recovery

A. Vanhatalo1, T. Chan1, J. Aalto1,2, J. F. Korhonen1, P. Kolari3, T. Hölttä1, E. Nikinmaa1, and J. Bäck1 A. Vanhatalo et al.
  • 1Department of Forest Sciences, University of Helsinki, Helsinki, Finland
  • 2SMEAR II station, University of Helsinki, Helsinki, Finland
  • 3Department of Physics, University of Helsinki, Helsinki, Finland

Abstract. Tree canopies are known to emit large amounts of VOCs (volatile organic compounds) such as monoterpenes into the surrounding air. High VOC emission rates from boreal forests have been observed during the transition from winter to summer activity. The most important sources of these are considered to be the green foliage, understory vegetation and soil organisms, but emissions from the living stand woody compartments have so far not been quantified. We analyzed whether the non-foliar components could partially explain the springtime high emission rates. We measured the monoterpene emissions from Scots pine (Pinus sylvestris L.) stem and shoots during the dehardening phase of trees in field conditions in two consecutive springs. We observed a large, transient monoterpene burst from the stem, while the shoot monoterpene emissions remained low. The burst lasted about 12 h. Simultaneously, an unusual nighttime sap flow and a non-systematic diurnal pattern of tree diameter were detected. Hence, we suggest that the monoterpene burst was a consequence of the recovery of the stem from wintertime, and likely related to the refilling of embolized tracheids and/or phenological changes in the living cells of the stem. This indicates that the dominant processes and environmental drivers triggering the monoterpene emissions are different between the stem and the foliage.

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Short summary
Boreal coniferous trees emit plenty of volatile monoterpenes into the atmosphere. At our measurement site in Finland, we found a springtime relation between the high monoterpene emission from Scots pine stem and tree water relations. Hence, we suggest that the transient monoterpene burst may be a consequence of the spring recovery of the stem and that the dominant processes and environmental drivers triggering the monoterpene emissions are different between pine stems and foliage.
Boreal coniferous trees emit plenty of volatile monoterpenes into the atmosphere. At our...
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