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| Titel |
Controls on winter ecosystem respiration in temperate and boreal ecosystems |
| VerfasserIn |
T. Wang, P. Ciais, S. L. Piao, C. Ottlé, P. Brender, F. Maignan, A. Arain, A. Cescatti, D. Gianelle, C. Gough, L. Gu, P. Lafleur, T. Laurila, B. Marcolla, H. Margolis, L. Montagnani, E. Moors, N. Saigusa, T. Vesala, G. Wohlfahrt, C. Koven, A. Black, E. Dellwik, A. Don, D. Hollinger, A. Knohl, R. Monson, J. Munger, A. Suyker, A. Varlagin, S. Verma |
| 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 ; 8, no. 7 ; Nr. 8, no. 7 (2011-07-25), S.2009-2025 |
| Datensatznummer |
250006056
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| Publikation (Nr.) |
 copernicus.org/bg-8-2009-2011.pdf |
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| Zusammenfassung |
| Winter CO2 fluxes represent an important component of the annual carbon
budget in northern ecosystems. Understanding winter respiration processes
and their responses to climate change is also central to our ability to
assess terrestrial carbon cycle and climate feedbacks in the future.
However, the factors influencing the spatial and temporal patterns of winter
ecosystem respiration (Reco) of northern ecosystems are poorly
understood. For this reason, we analyzed eddy covariance flux data from 57
ecosystem sites ranging from ~35° N to ~70° N.
Deciduous forests were characterized by the highest winter Reco rates
(0.90 ± 0.39 g C m−2 d−1), when winter is defined as the
period during which daily air temperature remains below 0 °C. By
contrast, arctic wetlands had the lowest winter Reco rates (0.02 ±
0.02 g C m−2 d−1). Mixed forests, evergreen needle-leaved forests,
grasslands, croplands and boreal wetlands were characterized by intermediate
winter Reco rates (g C m−2 d−1) of 0.70(±0.33), 0.60(±0.38),
0.62(±0.43), 0.49(±0.22) and 0.27(±0.08),
respectively. Our cross site analysis showed that winter air (Tair) and
soil (Tsoil) temperature played a dominating role in determining the
spatial patterns of winter Reco in both forest and managed ecosystems
(grasslands and croplands). Besides temperature, the seasonal amplitude of
the leaf area index (LAI), inferred from satellite observation, or growing
season gross primary productivity, which we use here as a proxy for the
amount of recent carbon available for Reco in the subsequent winter,
played a marginal role in winter CO2 emissions from forest ecosystems.
We found that winter Reco sensitivity to temperature variation across
space (QS) was higher than the one over time (interannual, QT).
This can be expected because QS not only accounts for climate gradients
across sites but also for (positively correlated) the spatial variability of
substrate quantity. Thus, if the models estimate future warming impacts on
Reco based on QS rather than QT, this could overestimate the
impact of temperature changes. |
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