Modélisation de la structure en diameter des reboisements et des peuplements naturels de cèdre de l’atlas (Cedrus atlantica manetti) du djurdjura (Algérie)

Abstract

The objective of this study was to understand the diameter structure of three even-aged Atlas cedar stands and four others representing different development stages (thicket, sapling, pole stage and high forest stage), which occupy various surfaces in the Tikjda natural cedar forest (Djurdjura, Algeria). The modelling approach for the structures observed was to seek a fit with the theoretical Weibull distribution. Goodness-of-fit tests showed that this distribution was well chosen. In terms of shape, the structure was unbalanced because no silvicultural action was taken to gradually decrease tree numbers so that remaining stock diameter could increase with age. The comparison between the even-aged stand structures and those of stands at various stages of development showed that apart from a shift to the right of the modal class indicating tree growth, the slight decrease in numbers is mainly due to competition and natural selection since no silvicultural practises have been implemented in this cedar forest.