Répartition de la matière sèche entre les organes végétatifs et reproducteurs dans les pousses annuelles du hêtre européen (Fagus sylvatica)

Resource allocations in plants can be estimated to study biomass distribution in the various organs during a vegetative cycle. Six isolated Europeen beech trees (Fagus sylvatica L.) of the same age were chosen within a station characterized by homogeneous ecological conditions: 229 annual shoots located on equivalent first order axes in the ramification were analysed to describe the distribution of dry material in leaves and stipules (for maintenance), in the axis (for present growth), in buds (for future growth), in infructescences (for female reproduction), and in male inflorescences (for male reproduction). The discrimination between acquisitions and allocations, which correspond to two different but complementary realities, is discussed. Development strategies are different between long and short vegetative shoots; the first one favours growth to explore the environment while the latter favours the maintenance to exploit it. When these two kinds of shoots flower and have additional resources, these new acquisitions are profitable both to vegetative and reproductive functions in short shoots, whereas a competition occurs between these functions in long shoots. Key words: resource allocations, dry material, annual shoots, European beech, Fagus sylvatica.