Predictive equations of some stand characteristics for Pinus brutia Ten. in Zawita and Atrush districts

الملخص EN

This study was done on 200 trees of natural pine stands (Pinus brutia Ten.) located in Zawita and Atrush district in Duhok province in northern Kurdistan region of Iraq.

The paper presents the analysis of some characteristics of tree, following elements were analyzed: diameter at breast height (D), tree height (H), crown diameter (CD) and age of tree at breast height (A).

We discuss the approaches of equations in order to establish the relationships between tree height with diameter at breast height (H-D), crown diameter with diameter at breast height (CD-D), age of tree at breast height with diameter at breast height (A-D), and age of tree at breast height with crown diameter (A-CD).

Regression analysis were applied, one linear and seven non-linear functions were selected for each of these relationships, and then were compared between these equations in order to choose the best fit equation by examining the adjusted coefficient of determination (R2 adj.), Standard error of estimated (SE.

of Est.) and the mean square error (MSE).

The results of the study indicated that the (H-D), (CD-D), (A-D) can be described by cubic function, except the relationship between (A-CD) can be described by quadratic function.