Ali Thabit^*(1)

(1). Natural Renewable Resources and Environment Department, Faculty of Agriculture, Aleppo University, Aleppo, Syria.

(*Corresponding author: Dr. Ali Thabit. E-Mail: alithabt@yahoo.fr).

Received: 02/08/2018                                Accepted: 24/09/2018

Abstract

The aim of this research was to design and test height-diameter models of Cupressus sempervirens in Misiaf, Syria. Modelling techniques were applied at four sampling plots that were selected throughout the natural distribution area of Cupressus sempervirens in Misiaf region. The tree height (h) and diameter at breast height (dbh) of eighty-four trees (84) were measured. Different forms of mathematical models (Michailoff, Parabel, Prodan, Petterson, Korsun, and Logarithmic) were selected to estimate the trees height of Cupressus sempervirens using diameter at breast height (dbh) as independent variable. Models were examined using different statistical tests i.e. absolute mean of the model error, relative mean of the model error, standard error of the absolute mean of the model error, model accuracy, model accuracy % and coefficient of determination R², which showed the proportion of the total variance that is explained by model. These statistical tests were done to select the best model to estimate the trees height of Cupressus sempervirens in Misiaf region in Syria. The results of model’s efficiency tests showed that the best function was Parabel equation, this model had a high R-squared value (R² = 60.8 %), less error value (0.21), and best accuracy value (m_x = 19 %). The results of this research could be a good tool in management of Cupressus sempervirens sites and could help forest managers in the future studies in the field.

Keywords: Cupressus sempervirens, Height–Diameter relationships, Mathematical modelling, Syria.

Full paper in Arabic: PDF