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Accueil du site → Doctorat → États-Unis → 1988 → Whole-stand and diameter distribution growth and yield models for Cedrus atlantica stands in Morocco

University of Idaho (1988)

Whole-stand and diameter distribution growth and yield models for Cedrus atlantica stands in Morocco

Khatouri, Mohamed

Titre : Whole-stand and diameter distribution growth and yield models for Cedrus atlantica stands in Morocco

Auteur : Khatouri, Mohamed

Université de soutenance : University of Idaho

Grade : Doctor of Philosophy (PhD) 1988

Résumé
The objective of this study was to develop a model for predicting growth and yield of uneven-aged cedar (Cedrus atlantica Manetti) stands in Morocco. The model incorporates whole-stand growth equations and diameter distribution approaches for predicting growth and yield. From temporary plots, a system of eleven linear and nonlinear differential equations was developed. The system relates the rates of change in per hectare values of the number of trees, the sum of diameters, and the basal area of each component of growth to the initial stand attribute conditions. A numerical integration of the system of stand level-equations provides growth and yield projections through time. Stand stock-tables to describe the product-size class information of the stand are obtained by estimating Weibull distribution parameters from the results of the system of stand-level equations. The components of growth modeled in the system were ingrowth, mortality, and survivor growth. The results indicated that certain stand attributes were the main predictor variables of these growth components. When there is relatively abundant regeneration in the stand, the predicted ingrowth rate is inversely related to stand basal area. The mortality rate is high where there is a relatively large number of trees in the stand and increases as the stand basal area increases. A large sum of survivor growth diameter rates is predicted with stands of small mean tree diameters, and a large number of trees per hectare. The survivor growth stand basal area rate is predicted to decrease as the stand basal area increases. The model is written in Fortran and runs in an interactive mode on a microcomputer. All mathematical estimation routines required for the projection are implemented in the program. The model is designed to be a valuable component in the forest management planning system of the cedar stands.

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