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| Titel |
Delayed responses of an Arctic ecosystem to an extreme summer: impacts on net ecosystem exchange and vegetation functioning |
| VerfasserIn |
D. Zona, D. A. Lipson, J. H. Richards, G. K. Phoenix, A. K. Liljedahl, M. Ueyama, C. S. Sturtevant, W. C. Oechel |
| 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 ; 11, no. 20 ; Nr. 11, no. 20 (2014-10-24), S.5877-5888 |
| Datensatznummer |
250117654
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| Publikation (Nr.) |
 copernicus.org/bg-11-5877-2014.pdf |
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| Zusammenfassung |
| The importance and consequences of extreme events on the global carbon budget
are inadequately understood. This includes the differential impact of extreme
events on various ecosystem components, lag effects, recovery times, and
compensatory processes. In the summer of 2007 in Barrow, Arctic Alaska,
there were unusually high air temperatures (the fifth warmest summer over a
65-year period) and record low precipitation (the lowest over a 65-year
period). These abnormal conditions were associated with substantial
desiccation of the Sphagnum layer and a reduced net
Sphagnum CO2 sink but did not affect net ecosystem exchange
(NEE) from this wet-sedge arctic tundra ecosystem. Microbial biomass,
NH4+ availability, gross primary production (GPP), and ecosystem
respiration (Reco) were generally greater during this extreme
summer. The cumulative ecosystem CO2 sink in 2007 was similar to the
previous summers, suggesting that vascular plants were able to compensate for Sphagnum CO2 uptake, despite the impact on other functions and structure such as
desiccation of the Sphagnum layer. Surprisingly, the lowest
ecosystem CO2 sink over a five summer record (2005–2009) was observed
during the 2008 summer (~70% lower), directly following the
unusually warm and dry summer, rather than during the extreme summer. This
sink reduction cannot solely be attributed to the potential damage to mosses,
which typically contribute ~40% of the entire ecosystem CO2
sink. Importantly, the return to a substantial cumulative CO2 sink
occurred two summers after the extreme event, which suggests a substantial
resilience of this tundra ecosystem to at least an isolated extreme event.
Overall, these results show a complex response of the CO2 sink and its
sub-components to atypically warm and dry conditions. The impact of multiple
extreme events requires further investigation. |
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