title: In situ assessment of the velocity of carbon transfer by tracing 13 C in trunk CO2 efflux after pulse labelling: variations among tree species and seasons.
abstract: Phloem is the main pathway for transferring photosynthates belowground. In situ(13) C pulse labelling of trees 8-10 m tall was conducted in the field on 10 beech (Fagus sylvatica) trees, six sessile oak (Quercus petraea) trees and 10 maritime pine (Pinus pinaster) trees throughout the growing season. Respired (13) CO2 from trunks was tracked at different heights using tunable diode laser absorption spectrometry to determine time lags and the velocity of carbon transfer (V). The isotope composition of phloem extracts was measured on several occasions after labelling and used to estimate the rate constant of phloem sap outflux (kP ). Pulse labelling together with high-frequency measurement of the isotope composition of trunk CO2 efflux is a promising tool for studying phloem transport in the field. Seasonal variability in V was predicted in pine and oak by bivariate linear regressions with air temperature and soil water content. V differed among the three species consistently with known differences in phloem anatomy between broadleaf and coniferous trees. V increased with tree diameter in oak and beech, reflecting a nonlinear increase in volumetric flow with increasing bark cross-sectional area, which suggests changes in allocation pattern with tree diameter in broadleaf species. Discrepancies between V and kP indicate vertical changes in functional phloem properties.
authors.affiliation: INRA, UR1263 Ecologie Fonctionnelle et Physique de l'Environnement, F-33140 Villenave d'Ornon, France.|Laboratory of Forest Utilization, Department of Forest and Biomaterial Science, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan.
authors.forename: Masako
authors.initials: M
authors.lastname: Dannoura
authors.affiliation: Université Henri Poincaré, UMR 1137, Ecologie et Ecophysiologie Forestières, Faculté des Sciences, Nancy Université, F-54500 Vandoeuvre les Nancy, France.|INRA, UMR 1137, Ecologie et Ecophysiologie Forestières, Centre de Nancy, F-54280 Champenoux, France.
authors.forename: Pascale
authors.initials: P
authors.lastname: Maillard
authors.affiliation: Université Paris-Sud, UMR 8079, Laboratoire Ecologie Systématique et Evolution, F-91405 Orsay, France.|CNRS, UMR 8079, Laboratoire Ecologie Systématique et Evolution, F-91190 Gif-sur-Yvette, France.|AgroParisTech, UMR 8079, Laboratoire Ecologie Systématique et Evolution, F-75231 Paris, France.
authors.forename: Chantal
authors.initials: C
authors.lastname: Fresneau
authors.affiliation: Université Henri Poincaré, UMR 1137, Ecologie et Ecophysiologie Forestières, Faculté des Sciences, Nancy Université, F-54500 Vandoeuvre les Nancy, France.|INRA, UMR 1137, Ecologie et Ecophysiologie Forestières, Centre de Nancy, F-54280 Champenoux, France.
authors.forename: Caroline
authors.initials: C
authors.lastname: Plain
authors.affiliation: Université Paris-Sud, UMR 8079, Laboratoire Ecologie Systématique et Evolution, F-91405 Orsay, France.|CNRS, UMR 8079, Laboratoire Ecologie Systématique et Evolution, F-91190 Gif-sur-Yvette, France.|AgroParisTech, UMR 8079, Laboratoire Ecologie Systématique et Evolution, F-75231 Paris, France.
authors.forename: Daniel
authors.initials: D
authors.lastname: Berveiller
authors.affiliation: Université Henri Poincaré, UMR 1137, Ecologie et Ecophysiologie Forestières, Faculté des Sciences, Nancy Université, F-54500 Vandoeuvre les Nancy, France.|INRA, UMR 1137, Ecologie et Ecophysiologie Forestières, Centre de Nancy, F-54280 Champenoux, France.
authors.forename: Dominique
authors.initials: D
authors.lastname: Gerant
authors.affiliation: INRA, UR1263 Ecologie Fonctionnelle et Physique de l'Environnement, F-33140 Villenave d'Ornon, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Chipeaux
authors.affiliation: INRA, UR1263 Ecologie Fonctionnelle et Physique de l'Environnement, F-33140 Villenave d'Ornon, France.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Bosc
authors.affiliation: Université Paris-Sud, UMR 8079, Laboratoire Ecologie Systématique et Evolution, F-91405 Orsay, France.|CNRS, UMR 8079, Laboratoire Ecologie Systématique et Evolution, F-91190 Gif-sur-Yvette, France.|AgroParisTech, UMR 8079, Laboratoire Ecologie Systématique et Evolution, F-75231 Paris, France.
authors.forename: Jérôme
authors.initials: J
authors.lastname: Ngao
authors.affiliation: Université Paris-Sud, UMR 8079, Laboratoire Ecologie Systématique et Evolution, F-91405 Orsay, France.|CNRS, UMR 8079, Laboratoire Ecologie Systématique et Evolution, F-91190 Gif-sur-Yvette, France.|AgroParisTech, UMR 8079, Laboratoire Ecologie Systématique et Evolution, F-75231 Paris, France.
authors.forename: Claire
authors.initials: C
authors.lastname: Damesin
authors.affiliation: INRA, UR1263 Ecologie Fonctionnelle et Physique de l'Environnement, F-33140 Villenave d'Ornon, France.
authors.forename: Denis
authors.initials: D
authors.lastname: Loustau
authors.affiliation: Université Henri Poincaré, UMR 1137, Ecologie et Ecophysiologie Forestières, Faculté des Sciences, Nancy Université, F-54500 Vandoeuvre les Nancy, France.|INRA, UMR 1137, Ecologie et Ecophysiologie Forestières, Centre de Nancy, F-54280 Champenoux, France.
authors.forename: Daniel
authors.initials: D
authors.lastname: Epron
mesh_terms: D018533:Biomass; D002244:Carbon / Q000378:metabolism*; D002245:Carbon Dioxide / Q000378:metabolism*; D002247:Carbon Isotopes / Q000378:metabolism; D019069:Cell Respiration; D029964:Fagus / Q000378:metabolism; D007553:Isotope Labeling; D007700:Kinetics; D052585:Phloem / Q000378:metabolism; D028223:Pinus / Q000378:metabolism; D024301:Plant Bark / Q000033:anatomy & histology; D010936:Plant Extracts / Q000378:metabolism; D029963:Quercus / Q000378:metabolism; D012621:Seasons; D013045:Species Specificity; D013696:Temperature; D013997:Time Factors; D014197:Trees / Q000378:metabolism*
chemical_list: D002247:Carbon Isotopes; D010936:Plant Extracts; D002245:Carbon Dioxide; D002244:Carbon