Biologie des chênes Algériens

Abstract

Various representatives of the genus Quercus play a more or less important role in the formation of Algerian forests. The current status of these populations in Algeria, the regression of its range, its ecological importance and necessity in the current global context, to promote biodiversity conservation and sustainable development of ecosystems are all elements that encouraged us to study the biology of oaks in Algeria. Growth and development of oak obey to rhythmicity characterized by repeated waves of "flush" growth which vary in length from 1 to 5 weeks, which is also reflected in a heteroblastia. Modifying the expression of rhythmic growth (spatio-temporal components) is caused by several factors such as extremes temperature (low and high), the involvement of growth regulators (gibberellin, cytokinin), removing young leaves, continuous light and darkness. Histological study of the oak buds shows that all units of the next leaf stage are preformed in the bud, continuous organogenesis (part of the leaf sets of the wave of growth n is formed during the resting phase of the wave n-1 and the other during the elongation phase of the wave n) and assimilates synthesized by the leaves of the wave of growth n, are used in the construction of the wave n + 1.