Influence de la comp�tition herbac�e sur la croissance et l'architecture de jeunes Ch�nes rouges d'Am�rique ( Quercus rubra L.) en plantation

Abstract

Young red oak trees planted on a former agricultural soil have been submitted to two extreme levels of herbaceous competition combined with two levels of fertilization. The herbaceous competition is associated with a decrease of 70% of the mean total height and with a decrease of 18% to 86% of the number of growth units produced each year. It induced also a decrease of 50% of the growth units mean number of internodes and leaves and a decrease of 30% up to 60% in its mean internode length. Initial fertilization stimulated only diameter growth of weeded trees. The number of branches per growth unit is lower for non-weeded trees (between –20% and –80%), but not different or upper per length unit, and oldest branch mortality is higher in relation to light competition. In a general way, weeds competition tends to limit tree crown expansion and the expression of the architectural sequence of differentiation.