ATM Newsletter Special Anniversary Edition

RESEARCH
ATM Newsletter #27. 07.April.2016
Are boreal trees a source of
greenhouse gases?
Text by Mari Pihlatie. Edited: Elisa Halmeenmäki
Pinus sylvestris as a missing source of nitrous oxide and
methane in boreal forest
The question whether boreal trees can emit methane
(CH4) and nitrous oxide (N2O) has been puzzling us
for some years. Generally, boreal forests are considered
as sinks and peatlands as sources of the strong
greenhouse gas CH4, while both of these ecosystems
are considered as small sources of N2O. Recently,
upland vegetation has been found to emit CH4 to
the atmosphere from a hitherto unknown process. If
also upland trees produce considerably CH4, forest
ecosystems could change from a sink to a source
of CH4. With these questions, we started intensive
field measurements at SMEAR II Scots pine (Pinus
sylvestris) forest in Hyytiälä. Here we present our
first results from measurements in 2013 showing that
mature Scots pine trees can emit both N2O and CH4
from both stems and shoots under field conditions.
We also demonstrate that Scots pine trees can considerably
contribute to the N2O
and CH4 exchange in an upland
forest ecosystem. These are our
first results from METAFOR
project funded by Emil Aaltonen
Foundation (2014–2016) and
ExpeER TNA. We continue the
work within Academy Research
Fellow project METATREE (Seasonality
in the production, transport and emissions
of CH4 from trees in boreal forest ecosystems) in order
to quantify the role of trees in the CH4 exchange
between forest and the atmosphere, to understand
processes behind the emissions or uptake, and to
identify environmental factors controlling the CH4
and N2O dynamics.
For more information: Mari Pihlatie, mari.pihlatie@
helsinki.fi, +358 50 4602748
Machacova, K. et al. Pinus sylvestris as a missing
source of nitrous oxide and methane
in boreal forest. Sci. Rep. 6, 23410; doi: 10.1038/
srep23410 (2016).
Figure S1. Schematic illustration
of N2O and CH4 fluxes in soiltree-atmosphere
continuum.”
(extracted from Supplementary
information)
ATMNewsletter 17