Architecture et gradients morphogénétiques chez de jeunes hêtres Fagus sylvatica L. Fagaceae) en milieu forestier

Abstract

The objective of this study was to describe the different morphological gradients being used as the basis for the development of the shape of the stem system in young forest-grown 7-year-old beeches, while characterizing the structural evolution of successively produced annual shoots in relation to the timing of their formation as well as their topological situation among tree stem systems. Three simple morphogenetic gradients explain the developmental dynamics of their overall stem system and the evolution in time and space of the morphogenetic functioning of their primary meristem structure. The first one illustrates structure settings by progressive increase of annual growth rate (increase of foliated node number and of annual shoot length) and of the branching angle of the trunk, as well as of successively produced twigs. The second gradient is represented by the "primary acrotonic" phenomenon described by Rauh in beech, which encourages formation and development of the highest lateral axes on the annual shoot. The third one is characterized by a gradual reduction in annual growth rate as well as of the branching angle of the lowest axes of the tree, indicating their decline and their imminent elimination by natural pruning.Key words: beech, architecture, growth, ramification, polycyclism, morphology.[Translated by editorial staff]