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| Titel |
Investigating carbon turnover in the Arctic tundra using a 13C pulse-chase approach |
| VerfasserIn |
J.-A. Subke, V. Leronni, H. W. Vallack, A. Heinemeyer, P. Ineson |
| 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 |
250023569
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| Zusammenfassung |
| Climatic models predict significant warming in the Arctic, with profound impacts on the
carbon (C) balance of tundra ecosystems. A significant increase in respiration from
vegetation and particularly soils is anticipated, but equally an increase in C assimilation by
tundra vegetation in response to warmer temperatures is likely. Our ability to predict likely
changes in the C balance in tundra ecosystems relies on the use of C exchange
models between plants, soils, and the atmosphere, but at the moment, data on critical
processes such as C assimilation and release are scarce. A key question in this context
relates to the fractions of assimilated C retained in plant biomass, and those allocated
to respiratory processes, which determine the rate of C turnover in the plant-soil
system.
We present data from a 13C pulse-chase experiment on 4 contrasting plant and lichen
communities in the Swedish tundra: (1) Betula dominated communities, (2) Empetrum heath
communities, (3) Carex (sedge) communities, and (4) exposed ridges (lichen communities).
The experiment was carried out at the location of a long-term flux monitoring experiment,
where the net ecosystem exchange of these 4 communities was measured continuously by
automated chambers. We assess the C turnover following a 3-hour pulse using isotopically
highly enriched (95 atom% 13C) CO2 by tracing the label through leaf biomass and return of
excess 13C in respiration from plants and soil over an 8-day period. The results indicate
a fast turnover of assimilated C in leaves, with a mean residence time (MRT) of
about 1 day, and no differences between communities. For the ecosystem respiration
flux, the isotopic label diminished at an even faster rate, with an MRT of less than
0.5 days. The 13C content in fine roots showed only a slight and not significant
enrichment 6 days after pulse labelling, while total soil (including fine roots) indicated a
significant increase for only one of the communities (Betula) from 6 days after
the labelling. The results are the first of this kind collected in tundra vegetation,
and provide valuable data to constrain C allocations used in ecosystem models. |
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