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| Titel |
Willows strongly emit methane (CH4) during dormant season |
| VerfasserIn |
Katerina Machacova, Klara Janebova, Stanislav Stellner, Jiri Dusek, Marian Pavelka, Renata Ryplova, Otmar Urban |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250154304
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| Publikation (Nr.) |
 EGU/EGU2017-19380.pdf |
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| Zusammenfassung |
| Wetlands are considered to be a substantial natural source of methane (CH4), due to
CH4 production by methanogens in flooded soil. Trees, especially wetland tree
species possessing an aerenchyma system in roots, are known to emit CH4 into the
atmosphere. However, information about the seasonal dynamics of tree CH4 emissions is
rare.
We determined CH4 emissions from stems of mature willow trees (Salix pentandra, S.
fragilis) in wetlands from March 2014 to September 2015. We aimed to investigate the
seasonal changes of CH4 emissions within the soil-tree-atmosphere continuum and the
impact of environmental parameters on these emissions. An intensive campaign
investigating vertical profile of CH4 emissions in stems was performed in May
2016.
The measurements were performed in sedge-grass marsh surrounding the ecosystem
station Wet Meadows in South Bohemia, Czech Republic (49˚ 01´30´´N,14˚ 46´20´´E), with
scattered willow trees. Emissions of CH4 were determined from stems and adjacent soil each
month using static chamber systems and laser analyses.
Our study revealed that all trees studied consistently emitted CH4 from their stems over
the whole year. The CH4 emissions were significantly higher in S. fragilis (up to 14.2 mg
CH4 m−2 stem area h−1) than in S. pentandra (up to 1.03 mg CH4 m−2 h−1), and
dramatically decreased within first 1.5 m of stem height with highest emissions detected close
to the soil surface. Even though the CO2 exchange of willow stems, as an indicator of their
physiological activity, showed strong seasonality typical for tree species of temperate zone
(high CO2 emissions during vegetation season followed by low, but still detectable
emissions in dormant season), the stems emitted CH4 in an opposite pattern. The CH4
emissions were the lowest in summer months (from June until August/September)
and dramatically increased from September onwards and remained very high and
almost constant until May. The soil even deposited CH4 from the atmosphere from
June until August/September, and emitted CH4 during the rest of the year with
highest emissions at the beginning and end of vegetation seasons. We assume that
CH4 is “passively” taken up by tree roots in the deepen soil layers, transported via
aerenchyma system to the bottom part of stems and released into the atmosphere
independently on the physiological activity of the trees. Ongoing regression analyses
with environmental/micrometeorological parameters will closer clarify the aspects
of the unique and very strong emissions of CH4 from the willow trees in winter
time.
Acknowledgement
This research was supported by the National Programme for Sustainability I (LO1415),
the Czech Science Foundation (17-18112Y) and CzeCOS (LM2015061). We thank Jiří
Mikula and Marek Jakubík for technical support. |
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