Nitrogen sources for current-year shoot growth in 50-year-old sessile oak trees: an in situ 15N labeling approach

1Universite Henri Poincare, UMR 1137 Ecologie et Ecophysiologie Forestieres IFR 110, Faculte des Sciences, F-54500 Vandoeuvre-les-Nancy, France; 2INRA, UMR 1137 Ecologie et Ecophysiologie Forestieres IFR 110, Centre INRA Nancy, F-54280 Champenoux, France; 3UMR 1138 INRA Nancy, Biogeochimie des Ecosystemes Forestiers, Centre INRA Nancy, F-54280 Champenoux, France; 4Corresponding author (maillard@nancy.inra.fr)