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| Titel |
The greenhouse gas balance of a drained fen peatland is mainly controlled by land-use rather than soil organic carbon content |
| VerfasserIn |
T. Eickenscheidt, J. Heinichen, M. Drösler |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 12, no. 17 ; Nr. 12, no. 17 (2015-09-02), S.5161-5184 |
| Datensatznummer |
250118082
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| Publikation (Nr.) |
 copernicus.org/bg-12-5161-2015.pdf |
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| Zusammenfassung |
| Drained organic soils are considered to be hotspots for greenhouse gas (GHG)
emissions. Arable lands and intensively used grasslands, in particular, have
been regarded as the main producers of carbon dioxide (CO2) and nitrous
oxide (N2O). However, GHG balances of former peatlands and associated
organic soils not considered to be peatland according to the definition of
the Intergovernmental Panel on Climate Change (IPCC) have not been
investigated so far. Therefore, our study addressed the question to what
extent the soil organic carbon (SOC) content affects the GHG release of
drained organic soils under two different land-use types (arable land and
intensively used grassland). Both land-use types were established on a Mollic
Gleysol (labeled Cmedium) as well as on a Sapric Histosol (labeled
Chigh). The two soil types differed significantly in their SOC
contents in the topsoil (Cmedium: 9.4–10.9 % SOC;
Chigh: 16.1–17.2 % SOC). We determined GHG fluxes over a
period of 1 or 2 years in case of N2O or methane (CH4) and
CO2, respectively. The daily and annual net ecosystem exchange (NEE) of
CO2 was determined by measuring NEE and the ecosystem respiration
(RECO) with the closed dynamic chamber technique and by modeling
the RECO and the gross primary production (GPP). N2O and
CH4 were measured with the static closed chamber technique. Estimated
NEE of CO2 differed significantly between the two land-use types, with
lower NEE values (−6 to 1707 g CO2-C m−2 yr−1) at the
arable sites and higher values (1354 to 1823 g
CO2-C m−2 yr−1) at the grassland sites. No effect on NEE was
found regarding the SOC content. Significantly higher annual N2O
exchange rates were observed at the arable sites (0.23–0.86 g
N m−2 yr−1) than at the grassland sites (0.12–0.31 g
N m−2 yr−1). Furthermore, N2O fluxes from the
Chigh sites significantly exceeded those of the Cmedium
sites. CH4 fluxes were found to be close to zero at all plots. Estimated
global warming potential, calculated for a time horizon of 100 years
(GWP100) revealed a very high release of GHGs from all plots ranging
from 1837 to 7095 g CO2 eq. m−2 yr−1. Calculated
global warming potential (GWP) values did not differ between soil types and
partly exceeded the IPCC default emission factors of the Tier 1 approach by
far. However, despite being subject to high uncertainties, the results
clearly highlight the importance of adjusting the IPCC guidelines for organic
soils not falling under the definition in order to avoid a significant
underestimation of GHG emissions in the corresponding sectors of the national
climate reporting. Furthermore, the present results revealed that mainly the
type of land-use, including the management type, and not the SOC content is
responsible for the height of GHG exchange from intensive farming on drained
organic soils. |
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