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| Titel |
Fast recovery of carbon fluxes in beech saplings after drought |
| VerfasserIn |
Carola Blessing, Matti Barthel, Lydia Gentsch, Nina Buchmann |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250109476
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| Publikation (Nr.) |
 EGU/EGU2015-15156.pdf |
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| Zusammenfassung |
| Drought is known to down-regulate above and belowground gas-exchange and to
slow down carbon transport from shoot to the soil/root system of beech (Fagus
sylvatica L.). However, given more frequent drought spells in a future climate,
the resilience of beech to drought will also depend on the speed and magnitude of
recovery of above and belowground carbon fluxes. In a climate chamber study with
beech saplings, we measured shoot and soil CO2 fluxes and their carbon isotope
signature during drought and consecutive recovery using laser spectroscopy. We
aimed to determine the speed of recovery from drought after re-watering and to
assess the coupling between above and belowground gas-exchange and carbon
isotope fluxes at natural abundance during drought and subsequent recovery. CO2
fluxes responded strongly to drought; photosynthesis was decreased by 34%, soil
respiration (during light) by 41% and stomatal conductance by 65%. Despite this
drastic decrease in gas-exchange, carbon fluxes recovered within few days after
re-watering – faster for aboveground physiological variables (four days) compared to soil
respiration (seven days) – pointing towards a resilient behaviour of beech saplings to
drought. Moreover, the drought response in soil respiration was better explained by
stomatal conductance (R2=0.8) rather than photosynthesis (R2=0.62). Consequently,
stomatal conductance, and thus water-mediated processes, played a pivotal role
driving the coupling of above and belowground CO2 fluxes. Further, drought caused
photosynthetic isotope discrimination to decrease by 8o which in turn was reflected in a
significant increase in δ13C of recent photoassimilates (1.5-2.5ÂoË) , and could be also
traced to δ13C of soil respiration, which increased by 1-1.5ÂoË) . However, the
coupling between the isotopic signatures of above and belowground carbon fluxes
(R2=0.15) was less pronounced compared to the coupling of above and belowground
gas-exchange (R2=0.8). In summary, our measurements highlight a fast recovery of beech
saplings from drought and the strong coupling between above and belowground
processes under drought and recovery with parallel responses of shoot and soil CO2
fluxes and their carbon isotope composition at natural carbon isotope abundance. |
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