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Comparison of seasonal variations in water‐use efficiency calculated from the carbon isotope composition of tree rings and flux data in a temperate forest
Author(s) -
MICHELOT ALICE,
EGLIN THOMAS,
DUFRÊNE ERIC,
LELARGETROUVERIE CAROLINE,
DAMESIN CLAIRE
Publication year - 2011
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.2010.02238.x
Subject(s) - transpiration , atmospheric sciences , water use efficiency , temperate rainforest , isotopes of carbon , canopy , dendrochronology , environmental science , quercus petraea , carbon flux , temperate climate , stomatal conductance , seasonality , mixing ratio , temperate forest , botany , photosynthesis , ecosystem , biology , ecology , total organic carbon , physics , paleontology
Tree‐ring δ 13 C is often interpreted in terms of intrinsic water‐use efficiency (WUE) using a carbon isotope discrimination model established at the leaf level. We examined whether intra‐ring δ 13 C could be used to assess variations in intrinsic WUE ( W g , the ratio of carbon assimilation and stomatal conductance to water) and variations in ecosystem WUE ( W t , the ratio of C assimilation and transpiration) at a seasonal scale. Intra‐ring δ 13 C was measured in 30‐ to 60‐ µ m‐thick slices in eight oak trees ( Quercus petraea ). Canopy W g was simulated using a physiologically process‐based model. High between‐tree variability was observed in the seasonal variations of intra‐ring δ 13 C. Six trees showed significant positive correlations between W g calculated from intra‐ring δ 13 C and canopy W g averaged over several days during latewood formation. These results suggest that latewood is a seasonal recorder of W g trends, with a temporal lag corresponding to the mixing time of sugars in the phloem. These six trees also showed significant negative correlations between photosynthetic discrimination Δ calculated from intra‐ring δ 13 C, and ecosystem W t , during latewood formation. Despite the observed between‐tree variability, these results indicate that intra‐ring δ 13 C can be used to access seasonal variations in past W t .