Stump Diameter and Diameter at Breast Height Relationships for Oriental Beech and Kazdağı Fir at Mixed Stands in Karabük

Abstract

Aim of study: The aim of this study was to evaluate the relationships between stump diameters ( d 0.10 and d 0.30 ) at two different stump heights (10 cm and 30 cm above ground level) and diameter at breast height ( d 1.30 ) for mixed stands of Oriental beech ( Fagus orientalis ) and Kazdağı fir ( Abies nordmanniana subsp. equi-trojani ) located in Karabük region. Area of study: Study area is located on Büyükdüz Forest Planning Unit of Karabük Forest Enterprise of Zonguldak Regional Directorate of Forestry at Western Blacksea region of Turkey. Material and Methods: A total of 516 sample trees (238 for Oriental beech and 278 for Kazdağı fir) were measured for d 0.10 , d 0.30 and d 1.30 . To model the relationships between stump diameters and diameter at breast height, ten candidate equations were tested. These equations were ranked according to Coefficient of Determination ( R 2 ), Root Mean Square Error ( RMSE ) and Mean Absolute Error ( MAE ), and successful models were selected based on average rank values. Main results: Among equations tested, the p ower equation had the lowest average rank values for determining d 0.10 - d 1.30 and d 0.30 - d 1.30 relationships of both species and provided the best d 1.30 predictions. R 2 , RMSE and MAE values of the power equation are 0.981, 3.64 and 2.58 for d 0.10 - d 1.30 relationship and 0.989, 2.01 and 1.36 for d 0.30 - d 1.30 relationship for Oriental beech, and 0.955, 3.80 and 2.81 for d 0.10 - d 1.30 relationship and 0.988, 1.96 and 1.28 for d 0.30 - d 1.30 relationship for Kazdağı fir, respectively. Research highlights: The equations developed can be used to estimate diameters at breast height of trees extracted from the stand for any reason, and volume of these trees can be predicted in a practical way by using single entry volume equations with the estimated diameters at breast heights.