Tree volume tables for Kazdağı Fir (Abies nordmanniana subsp. equi-trojani) stands in Safranbolu Region

Abstract

In this study, single and double entry over- and under-bark tree volume equations have been developed for Kazdağı Fir (Abies nordmanniana subsp. equi-trojani) stands within the boundaries of Safranbolu Forest Enterprise. The over- and under-bark volume values of 153 sample trees taken from different stand structures were used as the study material. Ten tree volume equations, five single- and five double-entry, were developed for over- and under-bark tree volume estimations. Four goodnes-of-fit criteria, including adjusted coefficient of determination, bias, mean absolute error, and root mean square error, were used to determine the most successful models. The suitability of the equations developed for the region was checked with an independent data set as well Wilcoxon test, and it was concluded that the equations were suitable for the study area (p>0.05). All tree volume equations proposed for the region had a coefficient of determination value over 0.95. In addition, the mean bias of the single- and double-entry models found to be the most successful for the region were calculated as -0.0211 m3 and -0.0122 m3 for the over-bark volume estimations, and -0.0201 m3 and 0.0045 m3 for the under-bark volume estimations, respectively. Single- and double-entry tree volume tables were prepared for over- and under-bark volume estimations by using the successful equations obtained as a result of the study.

Keywords

• double-entry volume equation
• over-bark stem volume
• under-bark stem volume
• forest inventory
• regression analysis
• çift-girişli hacim denklemi
• kabuklu gövde hacmi
• kabuksuz gövde hacmi
• orman envanteri
• regresyon analizi