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| Titel |
The role of snow cover affecting boreal-arctic soil freeze–thaw and carbon dynamics |
| VerfasserIn |
Y. Yi, J. S. Kimball, M. A. Rawlins, M. Moghaddam, E. S. Euskirchen |
| 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. 19 ; Nr. 12, no. 19 (2015-10-13), S.5811-5829 |
| Datensatznummer |
250118122
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| Publikation (Nr.) |
 copernicus.org/bg-12-5811-2015.pdf |
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| Zusammenfassung |
| Northern Hemisphere permafrost affected land
areas contain about twice as much carbon as the global atmosphere. This vast
carbon pool is vulnerable to accelerated losses through mobilization and
decomposition under projected global warming. Satellite data records spanning
the past 3 decades indicate widespread reductions
(~ 0.8–1.3 days decade−1) in the mean annual snow cover extent
and frozen-season duration across the pan-Arctic domain, coincident with
regional climate warming trends. How the soil carbon pool responds to these
changes will have a large impact on regional and global climate. Here, we
developed a coupled terrestrial carbon and hydrology model framework with a
detailed 1-D soil heat transfer representation to investigate the sensitivity
of soil organic carbon stocks and soil decomposition to climate warming and
changes in snow cover conditions in the pan-Arctic region over the past 3
decades (1982–2010). Our results indicate widespread soil active layer
deepening across the pan-Arctic, with a mean decadal trend of
6.6 ± 12.0 (SD) cm, corresponding to widespread warming. Warming
promotes vegetation growth and soil heterotrophic respiration particularly
within surface soil layers (≤ 0.2 m). The model simulations also show
that seasonal snow cover has a large impact on soil temperatures, whereby
increases in snow cover promote deeper (≥ 0.5 m) soil layer warming
and soil respiration, while inhibiting soil decomposition from surface (≤
0.2 m) soil layers, especially in colder climate zones (mean annual T
≤ −10 °C). Our results demonstrate the important control of
snow cover on northern soil freeze–thaw and soil carbon decomposition
processes and the necessity of considering both warming and a change in
precipitation and snow cover regimes in characterizing permafrost soil carbon
dynamics. |
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