title: Seasonal variations drive short-term dynamics and partitioning of recently assimilated carbon in the foliage of adult beech and pine.
abstract: 13CO2pulse-labelling experiments were performed in situ on adult beeches (Fagus sylvatica) and pines (Pinus pinaster) at different phenological stages to study seasonal and interspecific short-term dynamics and partitioning of recently assimilated carbon (C) in leaves. Polar fraction (PF, including soluble sugars, amino acids and organic acids) and starch were purified from foliage sampled during a 10-d chase period. C contents, isotopic compositions and13C dynamics parameters were determined in bulk foliage, PF and starch. Decrease in13C amount in bulk foliage followed a two-pool exponential model highlighting13C partitioning between 'mobile' and 'stable' pools, the relative proportion of the latter being maximal in beech leaves in May. Early in the growing season, new foliage acted as a strong C sink in both species, but although young leaves and needles were already photosynthesizing, the latter were still supplied with previous-year needle photosynthates 2 months after budburst. Mean13C residence times (MRT) were minimal in summer, indicating fast photosynthate export to supply perennial organ growth in both species. In late summer, MRT differed between senescing beech leaves and overwintering pine needles. Seasonal variations of13C partitioning and dynamics in field-grown tree foliage are closely linked to phenological differences between deciduous and evergreen trees.
authors: Ecologie et Ecophysiologie Forestières, Université de Lorraine, INRA, UMR 1137, Vandoeuvre-lès-Nancy F-54500, France.
authors: Dorine
authors: D
authors: Desalme
authors: Ecologie et Ecophysiologie Forestières, Université de Lorraine, INRA, UMR 1137, Vandoeuvre-lès-Nancy F-54500, France.
authors: Pierrick
authors: P
authors: Priault
authors: Ecologie et Ecophysiologie Forestières, Université de Lorraine, INRA, UMR 1137, Vandoeuvre-lès-Nancy F-54500, France.
authors: Dominique
authors: D
authors: Gérant
authors: INRA, UMR 1263, F-33883 Villenave d'Ornon, France.|Laboratory of Forest Utilization, Kyoto University, Kyoto 606-8502, Japan.
authors: Masako
authors: M
authors: Dannoura
authors: Ecologie et Ecophysiologie Forestières, Université de Lorraine, INRA, UMR 1137, Vandoeuvre-lès-Nancy F-54500, France.
authors: Pascale
authors: P
authors: Maillard
authors: Ecologie et Ecophysiologie Forestières, Université de Lorraine, INRA, UMR 1137, Vandoeuvre-lès-Nancy F-54500, France.
authors: Caroline
authors: C
authors: Plain
authors: Ecologie et Ecophysiologie Forestières, Université de Lorraine, INRA, UMR 1137, Vandoeuvre-lès-Nancy F-54500, France.
authors: Daniel
authors: D
authors: Epron
mesh_terms: D002244:Carbon / Q000378:metabolism*; D002247:Carbon Isotopes / Q000378:metabolism; D029964:Fagus / Q000378:metabolism*; D007700:Kinetics; D028223:Pinus / Q000378:metabolism*; D018515:Plant Leaves / Q000378:metabolism*; D012621:Seasons; D013213:Starch / Q000378:metabolism
chemical_list: D002247:Carbon Isotopes; D002244:Carbon; D013213:Starch
keywords: 
  Fagus sylvatica
  ; 
  Pinus pinaster
  ; 13C pulse labelling; carbon allocation; leaf carbon (C) residence time; soluble C compounds; starch; tree phenology