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| Titel |
The propagation of a soil H218O labeling through the atmosphere-plant-soil system under drought using H218O and C18OO as two independent proxies |
| VerfasserIn |
Matthias Barthel, Patrick Sturm, Albin Hammerle, Rolf Siegwolf, Lydia Gentsch, Nina Buchmann, Alexander Knohl |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250076950
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| Zusammenfassung |
| Above- and belowground processes in plants are tightly coupled via carbon and water flows
through the atmosphere-plant-soil system. While recent studies elucidated the influence of
drought on the carbon flow through plant and soil using 13C, much less is known
about the propagation of 18O. Therefore, this study aimed to examine the timing
and intensity of 18O enrichment in soil and shoot CO2 and H2O vapor fluxes of
European beech saplings (Fagus sylvatica L.) after applying 18O-labeled water to the
soil.
A custom-made chamber system, separating shoot from soil compartments, allowed
independent measurements of shoot and soil related processes in a controlled climate
chamber environment. Gas-exchange of oxygen stable isotopes in CO2 and H2O-vapor
served as the main tool for investigation and was monitored in real-time using laser
spectroscopy. This is the first study measuring concurrently and continuously the enrichment
of 18O in CO2 and H2O in shoot- and soil gas-exchange after applying 18O-labeled water to
the soil.
Photosynthesis (A) and stomatal conductance (gs) of drought-stressed plants showed an
immediate coinciding small increase to the H218O irrigation event after only ~30
min. This rapid information transfer, however, was not accompanied by the arrival
of 18O labeled water molecules within the shoot. The actual label induced 18O
enrichment in transpired water and CO2 occurred not until ~4h after labeling. Further,
the timing of the enrichment of 18O in the transpirational flux was similar in both
treatments, thus pointing to similar transport rates. However, drought reduced the 18O
exchange rate between H2O and CO2at the shoot level, likely caused by a smaller leaf
CO2retroflux. Moreover, 18O exchange between H2O and CO2 occurred also in
the soil. However, the there was no difference observed between the treatments. |
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