期刊
NEW PHYTOLOGIST
卷 188, 期 2, 页码 576-589出版社
WILEY
DOI: 10.1111/j.1469-8137.2010.03384.x
关键词
13CO(2); autotrophic respiration; carbon isotopes; forests; maritime pine; photosynthesis; plant allocation; tuneable diode laser
资金
- EU
- European Community [FP7/2007-2013, 237582]
- Region Aquitaine
- EFPA
P>Photosynthetic carbon (C) isotope discrimination (Delta(Alpha)) labels photosynthates (delta(A)) and atmospheric CO2 (delta(a)) 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 Delta(Alpha). We investigated the relationship between Delta(Alpha) and the C isotope signals from stem (delta(W)), soil (delta(S)) and ecosystem (delta(E)) respired CO2 to environmental fluctuations, using novel tuneable diode laser absorption spectrometer instrumentation in a mature maritime pine forest. Broad seasonal changes in Delta(Alpha) were reflected in delta(W,)delta(S) and delta(E). However, respired CO2 signals had smaller short-term variations than Delta(A) and were offset and delayed by 2-10 d, indicating fractionation and isotopic mixing in a large C pool. Variations in delta(S) did not follow Delta(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 CO2.
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