Genetic variation in productivity, leaf traits and carbon isotope discrimination in hybrid poplars cultivated on contrasting sites Ludovic Bonhomme, Cécile Barbaroux, Romain Monclus, Domenico Morabito, Alain Berthelot, Marc Villar, Erwin Dreyer and Franck BrignolasAnn. For. Sci., 65 5 (2008) 503DOI: https://doi.org/10.1051/forest:2008024