WOULD INCREASE IN UV-B RADIATION AFFECT METHANE RELEASE

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WOULD INCREASE IN UV-B RADIATION AFFECT METHANE
RELEASE FROM NORTHERN PEATLANDS? Pertti
Martikainen, Department of Environmental
Sciences, University of Kuopio QUEST Workshop,
University of Bristol, June 14-16, 2004
Effects of global change and anthropogenic
activities on carbon gas dynamics
There are data e.g. on the effects - of
changing hydrology on carbon gas dynamics - of
change in temperature on methane release - of
increase in atmospheric CO2 concentration on
carbon gas dynamics - of atmospheric nitrogen
and sulphate load on methane dynamics The
effects of increase in UV-B radiation on methane
(and CO2) dynamics in northern peatlands are
unknown - the boreal and subarctic regions (60
-90 oN) will be subjected to a 14
maximum increase in the annual UV dose in 2010-
20 relative to 1979 1992 (Taalas et al.
2000) - - the ozone depletion is most severe
during spring, increase in UV dose would be
90 from the level in 1979-1992. The increase
in UV radiation is a potential stress factor for
the peatland vegetation, and then also carbon
dynamics driven by plants and their
photosynthesis. There is a link between the
primary production and methanogenesis
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EXPERIMENTS WITH MICROCOSMS In 1999 Intact
peat cores with vegetation from lawn microsites
of a minero- genic, oligotrophic low-sedge S.
Papillosum pine fen, Eastern Finland
Effects of UV treatment on methane emissions from
peatlands
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Effects of ambient, UV-A control and UV-B
treatment on methane emissions from peatland
microcosms during the growing season 1999

• Intact peat cores (dia 10 cm, depth
• 40 cm) with vegetation from lawn
• microsites of a minerogenic,
• oligotrophic low-sedge
• S. Papillosum pine fen, Eastern
• Finland
• - Treatment by UV-B (constant 30
• above the ambient UV-B level)
• was done at an open-field exposure
• facility in Kuopio, Central Finland

(320 400 nm) (280 -320 nm)
UV-B treatment lowered the CH4 emission by
30 Decrease in photosynthesis (all
plants were included to the measurements
Changes in plant physiology and morphology
- increase in membrane leakage of S.
angustifolium by UV-B - UV-B reduced the
amount of aerenchymatous tissue of
Eriophorum vaginatum
Global Change Biology 8 361-371 (2002)
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• Sodankylä experimental site in
  Northern Finland,
• exposure started in
  summer 2003
• Mesotrophic flark fen (close to Sodankylä
  Geophysical Observatory)
  
  
• 10 control plots
• -10 plots treated with UV-A
• -10 plots treated with UV-B (continuously 30
  above the ambient)

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Collar in an experimental plot allowing gas-tight
connection of chambers for CO2 and CH4 exchange
studies
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PhD Sanna Saarnio shows how the CO2 dynamics is
measured using thermostated chamber and IR
analyzer. NEE, respiration and photosynthesis can
be measured, and using environmental data (e.g.
radiation, temperature, WT) the seasonal CO2
balance can be determined (modelled).
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PhD student Sami Mörsky in action measuring
methane fluxes with a static chamber method. Gas
samples are taken Into gas tight vials to be
analyzed later In laboratory for CH4 using a gas
chromatograph equipped with an autosampler.
After exposure of the first summer There was no
significant difference In the carbon gas fluxes.
It is known that the damages in vegetation
can require longer radiation stress.
The experiment will be continued at least for two
additional years including gas flux measurements
during all seasons. Possible changes in
plant morphology/ physiology and
soil processes/chemistry are also studied.