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| Titel |
A fertile peatland forest does not constitute a major greenhouse gas sink |
| VerfasserIn |
A. Meyer, L. Tarvainen, A. Nousratpour, R. G. Björk, M. Ernfors, A. Grelle, Åsa Kasimir Klemedtsson, A. Lindroth, M. Räntfors, T. Rütting, G. Wallin, P. Weslien, L. Klemedtsson |
| 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 ; 10, no. 11 ; Nr. 10, no. 11 (2013-11-28), S.7739-7758 |
| Datensatznummer |
250085446
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| Publikation (Nr.) |
 copernicus.org/bg-10-7739-2013.pdf |
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| Zusammenfassung |
| Afforestation has been proposed as a strategy to mitigate the often high
greenhouse gas (GHG) emissions from agricultural soils with high organic
matter content. However, the carbon dioxide (CO2) and nitrous
oxide (N2O) fluxes after afforestation can be considerable, depending
predominantly on site drainage and nutrient availability. Studies on the
full GHG budget of afforested organic soils are scarce and hampered by the
uncertainties associated with methodology. In this study we determined the
GHG budget of a spruce-dominated forest on a drained organic soil with an
agricultural history. Two different approaches for determining the net
ecosystem CO2 exchange (NEE) were applied, for the year 2008, one direct
(eddy covariance) and the other indirect (analyzing the different components of the
GHG budget), so that uncertainties in each method could be evaluated. The
annual tree production in 2008 was 8.3 ± 3.9 t C ha−1 yr−1
due to the high levels of soil nutrients, the favorable climatic conditions
and the fact that the forest was probably in its phase of maximum C
assimilation or shortly past it. The N2O fluxes were determined by the
closed-chamber technique and amounted to 0.9 ± 0.8 t Ceq ha−1 yr−1.
According to the direct measurements from the eddy
covariance technique, the site acts as a minor GHG sink of −1.2 ± 0.8
t Ceq ha−1 yr−1. This contrasts with the NEE estimate
derived from the indirect approach which suggests that the site is a net GHG
emitter of 0.6 ± 4.5 t Ceq ha−1 yr−1. Irrespective of
the approach applied, the soil CO2 effluxes counter large amounts of
the C sequestration by trees. Due to accumulated uncertainties involved in
the indirect approach, the direct approach is considered the more reliable
tool. As the rate of C sequestration will likely decrease with forest age,
the site will probably become a GHG source once again as the trees do not
compensate for the soil C and N losses. Also forests in younger age stages
have been shown to have lower C assimilation rates; thus, the overall GHG
sink potential of this afforested nutrient-rich organic soil is probably
limited to the short period of maximum C assimilation. |
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