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Assessing methane emissions for northern peatlands in ORCHIDEE-PEAT revision 7020
Ist Teil von
Geoscientific Model Development, 2022-04, Vol.15 (7), p.2813-2838
Ort / Verlag
Katlenburg-Lindau: Copernicus GmbH
Erscheinungsjahr
2022
Quelle
EZB Electronic Journals Library
Beschreibungen/Notizen
In the global methane budget, the largest natural source
is attributed to wetlands, which encompass all ecosystems composed of
waterlogged or inundated ground, capable of methane production. Among them,
northern peatlands that store large amounts of soil organic carbon have been
functioning, since the end of the last glaciation period, as long-term
sources of methane (CH4) and are one of the most significant methane
sources among wetlands. To reduce uncertainty of quantifying methane flux in the
global methane budget, it is of significance to understand the underlying
processes for methane production and fluxes in northern peatlands. A methane
model that features methane production and transport by plants, ebullition
process and diffusion in soil, oxidation to CO2, and CH4 fluxes to
the atmosphere has been embedded in the ORCHIDEE-PEAT land surface model
that includes an explicit representation of northern peatlands.
ORCHIDEE-PCH4 was calibrated and evaluated on 14 peatland sites distributed
on both the Eurasian and American continents in the northern boreal and
temperate regions. Data assimilation approaches were employed to optimized
parameters at each site and at all sites simultaneously. Results show that
methanogenesis is sensitive to temperature and substrate availability over
the top 75 cm of soil depth. Methane emissions estimated using single site
optimization (SSO) of model parameters are underestimated by 9 g CH4 m−2 yr−1 on average (i.e., 50 % higher than the site average of
yearly methane emissions). While using the multi-site optimization (MSO),
methane emissions are overestimated by 5 g CH4 m−2 yr−1 on
average across all investigated sites (i.e., 37 % lower than the site
average of yearly methane emissions).