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| Titel |
Positive feedback of elevated CO2 on soil respiration in late autumn and winter |
| VerfasserIn |
L. Keidel, C. Kammann, L. Grünhage, G. Moser, C. Müller |
| 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. 4 ; Nr. 12, no. 4 (2015-02-26), S.1257-1269 |
| Datensatznummer |
250117835
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| Publikation (Nr.) |
 copernicus.org/bg-12-1257-2015.pdf |
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| Zusammenfassung |
Soil respiration of terrestrial ecosystems, a major component in the global
carbon cycle is affected by elevated atmospheric CO2 concentrations.
However, seasonal differences of feedback effects of elevated CO2 have
rarely been studied. At the Gießen Free-Air CO2 Enrichment (GiFACE)
site, the effects of +20% above ambient CO2 concentration have
been investigated since 1998 in a temperate grassland ecosystem. We defined
five distinct annual seasons, with respect to management practices and
phenological cycles. For a period of 3 years (2008–2010), weekly
measurements of soil respiration were carried out with a survey chamber on
vegetation-free subplots. The results revealed a pronounced and repeated
increase of soil respiration under elevated CO2 during late autumn and
winter dormancy. Increased CO2 losses during the autumn season
(September–October) were 15.7% higher and during the winter season
(November–March) were 17.4% higher compared to respiration from ambient
CO2 plots.
However, during spring time and summer, which are characterized by strong
above- and below-ground plant growth, no significant change in soil
respiration was observed at the GiFACE site under elevated CO2. This
suggests (1) that soil respiration measurements, carried out only during the
growing season under elevated CO2 may underestimate the true
soil-respiratory CO2 loss (i.e. overestimate the C sequestered), and
(2) that additional C assimilated by plants during the growing season and
transferred below-ground will quickly be lost via enhanced heterotrophic
respiration outside the main growing season. |
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