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| Titel |
Nutrient loading enhances methane flux in an ombrotrophic bog |
| VerfasserIn |
Jill L. Bubier, Sari Juutinen, Tim Moore, Sini Arnkil, Elyn Humphreys, Brenden Marincak, Cameron Roy, Tuula Larmola |
| 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 |
250140304
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| Publikation (Nr.) |
 EGU/EGU2017-3672.pdf |
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| Zusammenfassung |
| Peatlands are significant sources of atmospheric methane (CH4) and emission rates may be
affected by atmospheric nutrient inputs and associated changes in vegetation. In a long-term
(10-15 yr) fertilization experiment at a nutrient-poor, Sphagnum moss- and dwarf
shrub-dominated bog in eastern Canada, we tested the effect of ammonium nitrate
(NH4NO3,0 to 6.4 g N m−2 yr−1) and potassium phosphate (KH2PO4,5 g P m−2 yr−1) on
fluxes of CH4. Fluxes were measured using a closed chamber technique over the growing
seasons of 2005 and 2015. The effect of long-term field treatments on aerobic consumption
and anaerobic production potentials of CH4 was tested by laboratory incubations
of peat samples, as well as an amendment with KH2PO4on anaerobic production
potentials at the water table. Over the 10-15 yr, three levels of N plus PK addition
and N-only addition of 6.4g N m−2yr−1 decreased the abundance of Sphagnum
and Polytrichum mosses, increased the growth and coverage of dwarf shrubs, and
caused a decline in surface elevation and thus a higher water table. Overall, CH4 flux
was small, ∼ 12 mg m−2 d−1 in the control plots, primarily because of the low
water table (30 to 50 cm beneath the peat surface), but flux varied as a function
of water table position and treatment. KH2PO4 addition was associated with the
highest fluxes: in the 5th treatment year, the PK treatment had the largest CH4 flux
(∼25 mg m−2 d−1), whereas in the 15th year the 6.4NPK treatment had the largest
flux (∼50 mg m−2 d−1). Rates of potential production and consumption of CH4in
laboratory incubations of peat samples were associated with position relative to the
water table. Anaerobic potential CH4production was largest in the PK treatment and
overall was marginally increased by PK amendment; there were no clear effects of
NH4NO3 on CH4 production. The major increase in CH4 flux appearing in the
long term seemed to be result of the change in water table position owing to peat
subsidence and loss of moss, plus potential stimulation of CH4 production by PK. |
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