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| Titel |
Bulk partitioning the growing season net ecosystem exchange of CO2 in Siberian tundra reveals the seasonality of its carbon sequestration strength |
| VerfasserIn |
B. R. K. Runkle, T. Sachs, C. Wille, E.-M. Pfeiffer, L. Kutzbach |
| 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. 3 ; Nr. 10, no. 3 (2013-03-01), S.1337-1349 |
| Datensatznummer |
250018127
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| Publikation (Nr.) |
 copernicus.org/bg-10-1337-2013.pdf |
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| Zusammenfassung |
| This paper evaluates the relative contribution of light and temperature on
net ecosystem CO2 uptake during the 2006 growing season in a polygonal
tundra ecosystem in the Lena River Delta in Northern Siberia
(72°22´ N, 126°30´ E). The occurrence and frequency of
warm periods may be an important determinant of the magnitude of the
ecosystem's carbon sink function, as they drive temperature-induced changes
in respiration. Hot spells during the early portion of the growing season,
when the photosynthetic apparatus of vascular plants is not fully developed,
are shown to be more influential in creating positive mid-day
surface-to-atmosphere net ecosystem CO2 exchange fluxes than those
occurring later in the season. In this work we also develop and present a
multi-step bulk flux partition model to better account for tundra plant
physiology and the specific light conditions of the arctic region. These
conditions preclude the successful use of traditional partition methods that
derive a respiration–temperature relationship from all nighttime data or
from other bulk approaches that are insensitive to temperature or light
stress. Nighttime growing season measurements are rare during the arctic
summer, however, so the new method allows for temporal variation in the
parameters describing both ecosystem respiration and gross uptake by fitting
both processes at the same time. Much of the apparent temperature sensitivity
of respiration seen in the traditional partition method is revealed in the
new method to reflect seasonal changes in basal respiration rates.
Understanding and quantifying the flux partition is an essential precursor to
describing links between assimilation and respiration at different timescales,
as it allows a more confident evaluation of measured net exchange
over a broader range of environmental conditions. The growing season CO2
sink estimated by this study is similar to those reported previously for this
site, and is substantial enough to withstand the long, low-level respiratory
CO2 release during the rest of the year to maintain the site's CO2 sink
function on an annual basis. |
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