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| Titel |
The amount and timing of precipitation control the magnitude, seasonality and sources (14C) of ecosystem respiration in a polar semi-desert, northwestern Greenland |
| VerfasserIn |
M. Lupascu, J. M. Welker, U. Seibt, X. Xu, I. Velicogna, D. S. Lindsey, C. I. Czimczik |
| 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. 16 ; Nr. 11, no. 16 (2014-08-19), S.4289-4304 |
| Datensatznummer |
250117548
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| Publikation (Nr.) |
 copernicus.org/bg-11-4289-2014.pdf |
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| Zusammenfassung |
This study investigates how warming and changes in precipitation may affect
the cycling of carbon (C) in tundra soils, and between high Arctic tundra and
the atmosphere. We quantified ecosystem respiration (Reco) and
soil pore space CO2 in a polar semi-desert in northwestern Greenland
under current and future climate conditions simulated by long-term
experimental warming (+2 °C, +4 °C), water addition
(+50% summer precipitation), and a combination of both
(+4 °C × +50% summer precipitation). We also
measured the 14C content of Reco and soil CO2 to
distinguish young C cycling rapidly between the atmosphere and the ecosystem
from older C stored in the soil for centuries to millennia.
We identified changes in the amount and timing of precipitation as a key
control of the magnitude, seasonality and sources of Reco in a
polar semi-desert. Throughout each summer, small (<4 mm) precipitation
events during drier periods triggered the release of very old C pulses from
the deep soil, while larger precipitation events (>4 mm), more winter
snow and experimental irrigation were associated with higher Reco
fluxes and the release of recently fixed (young) C. Warmer summers and
experimental warming also resulted in higher Reco fluxes
(+2 °C > +4 °C), but coincided with losses of older
C.
We conclude that in high Arctic, dry tundra systems, future magnitudes and
patterns of old C emissions will be controlled as much by the summer
precipitation regime and winter snowpack as by warming. The release of older
soil C is of concern, as it may lead to net C losses from the ecosystem.
Therefore, reliable predictions of precipitation amounts, frequency, and
timing are required to predict the changing C cycle in the high Arctic. |
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