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| Titel |
The contribution of litter derived carbon to winter respiration in an alpine tundra ecosystem |
| VerfasserIn |
S. Wipf, R. Siegwolf, J. Esperschuetz, F. Hagedorn |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250026006
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| Zusammenfassung |
| Although soil respiration rates from snow-covered ecosystems are relatively low, they add up
to a substantial fraction of the annual CO2 efflux over the whole winter, which lasts for more
than half of the year in the Alpine. It is still unclear, however, which carbon sources are
respired preferentially in winter.
In a new experiment at the Stillberg tree line research site near Davos, Switzerland, we added
13C-labelled litter (Leucanthemopsis alpina L.) to an alpine tundra ecosystem and measured
its contribution to the CO2 efflux at different soil temperatures over winter. The litter was
placed either at the soil surface or at 5 cm depth, and soil temperature was decreased by
manually reducing snow depth to half of of that of the control plots. Soil respiration was
measured by means of a chamber system, and gas samples were analysed for their isotopic
composition.
Preliminary results indicate that soil respiration in early winter was about half compared to
that measured in late fall. Lower soil temperatures under a shallow snow cover further
decreased respiration by 40%. Litter addition increased respiration rates by 10 to 30%. At the
beginning of the winter season, a higher respiration rate was found for the plots where litter
was applied at the surface than at 5 cm soil depth. This effect, however, decreased with the
progression of the winter as later measurements have shown. The isotopic composition of the
respired CO2 suggests that carbon from the additional litter contributed about 5 to 15%
to the total CO2 efflux, and that this fraction was higher in plots with lower soil
temperatures.
Our results show considerable and non negligible amounts of C-loss in winter. By exploring
the effect of the snow cover and soil temperatures on the decomposition of fresh plant litter,
this experiment will give a more detailed insight into the environmental controls
of soil respiration processes and the sources of respiratory CO2 release in Alpine
ecosystems. |
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