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Photosynthetic carbon isotope discrimination and its relationship to the carbon isotope signals of stem, soil and ecosystem respiration
Author(s) -
Wingate Lisa,
Ogée Jérôme,
Burlett Régis,
Bosc Alexandre,
Devaux Marion,
Grace John,
Loustau Denis,
Gessler Arthur
Publication year - 2010
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.2010.03384.x
Subject(s) - isotopes of carbon , isotope , biosphere , ecosystem , photosynthesis , isotope analysis , isotopic signature , stable isotope ratio , environmental science , environmental chemistry , isotope fractionation , context (archaeology) , soil respiration , atmospheric sciences , chemistry , fractionation , ecology , total organic carbon , biology , geology , physics , quantum mechanics , paleontology , biochemistry , organic chemistry
Summary• Photosynthetic carbon (C) isotope discrimination (Δ Α ) labels photosynthates (δ A ) and atmospheric CO 2 (δ a ) with variable C isotope compositions during fluctuating environmental conditions. In this context, the C isotope composition of respired CO 2 within ecosystems is often hypothesized to vary temporally with Δ Α . • We investigated the relationship between Δ Α and the C isotope signals from stem (δ W ), soil (δ S ) and ecosystem (δ E ) respired CO 2 to environmental fluctuations, using novel tuneable diode laser absorption spectrometer instrumentation in a mature maritime pine forest. • Broad seasonal changes in Δ Α were reflected in δ W, δ S and δ E . However, respired CO 2 signals had smaller short‐term variations than Δ A and were offset and delayed by 2–10 d, indicating fractionation and isotopic mixing in a large C pool. Variations in δ S did not follow Δ A 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 CO 2 .