Does <i>Juncus effusus</i> enhance methane emissions from grazed pastures on peat?
Methane (CH<sub>4</sub>) emissions from drained organic soils are generally low, but internal gas transport in aerenchymatous plants may result in local emission hotspots. In a paired-sample field study at three different sites we measured fluxes of CH<sub>4</sub> with static...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2015-10-01
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| Series: | Biogeosciences |
| Online Access: | http://www.biogeosciences.net/12/5667/2015/bg-12-5667-2015.pdf |
| Summary: | Methane (CH<sub>4</sub>) emissions from drained organic soils are generally low,
but internal gas transport in aerenchymatous plants may result in local
emission hotspots. In a paired-sample field study at three different sites
we measured fluxes of CH<sub>4</sub> with static chambers from adjacent sampling
quadrats with and without <i>Juncus effusus</i> during four field campaigns. At all three sites,
CH<sub>4</sub> was observed in the soil at all sampling depths (5 to 100 cm),
and in most cases both above and below the groundwater table. During spring,
local maxima suggested methanogenesis also took place above the water table at
all three sites. We found significant CH<sub>4</sub> emissions at all three sites,
but emission controls were clearly different. Across the three sites,
average emission rates (±1 SE) for sampling quadrats with and without
<i>J. effusus</i> were 1.47 ± 0.28 and 1.37 ± 0.33 mg CH<sub>4</sub> m<sup>−2</sup> h<sup>−1</sup>, respectively, with no overall effect of <i>J. effusus</i> on
CH<sub>4</sub> emissions. However, a significant effect of <i>J. effusus</i> was seen at one of
the three sites. At this site, local CH<sub>4</sub> maxima were closer to the
soil surface than at the other sites, and the upper soil layers were dryer.
This could have affected both root CH<sub>4</sub> accessibility and CH<sub>4</sub> oxidation respectively, and together with limited gas diffusivity in the
soil column, cause elevated CH<sub>4</sub> emissions from <i>J. effusus</i>. We conclude that
<i>J. effusus</i> has the potential to act as point sources of CH<sub>4</sub>
from drained peatlands, but more studies on the specific conditions under
which there is an effect, are needed before the results can be used in
modelling of CH<sub>4</sub> emissions. |
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| ISSN: | 1726-4170 1726-4189 |