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| Titel |
Can frequent precipitation moderate drought impact on peatmoss carbon uptake in northern peatlands? |
| VerfasserIn |
Jelmer Nijp, Juul Limpens, Klaas Metselaar, Sjoerd van der Zee, Frank Berendse, Bjorn Robroek |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250090191
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| Publikation (Nr.) |
 EGU/EGU2014-4412.pdf |
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| Zusammenfassung |
| Northern peatlands represent one of the largest global carbon stores that can potentially be
released by water table drawdown during extreme summer droughts. Small precipitation
events may moderate negative impacts of deep water levels on carbon uptake by
sustaining photosynthesis of peatmoss (Sphagnum spp.), the key species in these
ecosystems.
We experimentally assessed the importance of the temporal distribution of precipitation
for Sphagnum water supply and carbon uptake during a stepwise decrease in water levels in a
growth chamber. CO2 exchange and the water balance were measured for intact cores of three
peatmoss species representative of three contrasting habitats in northern peatlands
(Sphagnumfuscum, S.balticum and S.majus).
For shallow water levels, capillary rise was the most important source of water for
peatmoss photosynthesis and precipitation did not promote carbon uptake irrespective of
peatmoss species. For deep water levels, however, precipitation dominated over capillary rise
and moderated adverse effects of drought on carbon uptake by peat mosses. The ability to use
the transient water supply by precipitation was species-specific: carbon uptake of
S.fuscum increased linearly with precipitation frequency for deep water levels, whereas
S.balticum and S.majus showed depressed carbon uptake at intermediate precipitation
frequencies.
Our results highlight the importance of precipitation for carbon uptake by peatmosses.
The potential of precipitation to moderate drought impact, however, is species specific and
depends on the temporal distribution of precipitation and water level. These results also
suggest that modelling approaches in which water level depth is used as the only state
variable determining water availability in the living moss layer and (in)directly linked to
Sphagnum carbon uptake may have serious drawbacks. The predictive power of peatland
ecosystem models may be reduced when deep water levels prevail, as precipitation
frequency and quantity are likely the main variables controlling carbon uptake. |
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