WINGATE, Lisa; OGÉE, Jérôme; BURLETT, Régis; BOSC, Alexandre; DEVAUX, Marion; GRACE, John; LOUSTAU, Denis; GESSLER, Arthur

doi:10.1111/j.1469-8137.2010.03384.x

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WINGATE, Lisa
Écologie fonctionnelle et physique de l'environnement [EPHYSE]
School of GeoSciences
Department of Plant Sciences

OGÉE, Jérôme
Écologie fonctionnelle et physique de l'environnement [EPHYSE]

BURLETT, Régis
Biodiversité, Gènes & Communautés [BioGeCo]

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New Phytologist. 2010, vol. 188, n° 2, p. 576-589

Wiley

Résumé en anglais

Photosynthetic carbon (C) isotope discrimination (ΔΑ) labels photosynthates (δA) and atmospheric CO2 (δa) with variable C isotope compositions during fluctuating environmental conditions. In this context, the C isotope composition of respired CO2 within ecosystems is often hypothesized to vary temporally with ΔΑ. We investigated the relationship between ΔΑ and the C isotope signals from stem (δW), soil (δS) and ecosystem (δE) respired CO2 to environmental fluctuations, using novel tuneable diode laser absorption spectrometer instrumentation in a mature maritime pine forest. Broad seasonal changes in ΔΑ were reflected in δW,δS and δE. However, respired CO2 signals had smaller short-term variations than ΔA and were offset and delayed by 2–10 d, indicating fractionation and isotopic mixing in a large C pool. Variations in δS did not follow ΔA at all times, especially during rainy periods and when there is a strong demand for C allocation above ground. It is likely that future isotope-enabled vegetation models will need to develop transfer functions that can account for these phenomena in order to interpret and predict the isotopic impact of biosphere gas exchange on the C isotope composition of atmospheric CO2.< Réduire

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Photosynthetic carbon isotope discrimination and its relationship to the carbon isotope signals of stem, soil and ecosystem respiration

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Résumé en anglais

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