Developing Single and Double Tree Volume Equations for Crimean Pine [Pinusnigra Arnold. subsp. pallasiana (Lamb.)Holmboe]in Mudurnu-Sırçalı Forest District Enterprise

The tree volume that are essential yield of forests constitute a main portion of the capital of forest enterprise, thus the best important production output of a forest enterprise are that the wood assortments, i.e. timber, mine poles, sawlogs, firewoods and industrial wood, obtained from tree. In this regard, the main supports for forest enterprise are the tree volume equations and tables which can predict individual tree volume. In this study, The single and double entry volume equations were developed for Crimean Pine [PinusnigraArnold. subsp. pallasiana (Lamb.) Holmboe] trees located in Sircali Planning Unit, Mudurnu Forest Enterprise, Bolu Forest District Directorate. The six functions for single entry volume equations and twenty-seven functions for double entry volume equations were compared by using six fitting performance criteria, i. e. standard deviation of residuals, average residuals or bias, average absolute residuals, total error percentage, absolute mean error percentage and coefficient of determination. In comparisons including some statistical indices, single entry volume equation with 86.06 % of the coefficient of determination and double entry volume equation with 97.45 % of the coefficient of determination were found to produce the most satisfactory fits than other equation.The best predictive single and double entry volume equations were decided to be appropriate at 0.05 significant level for the studied Crimean pine trees by testing independent data. In this study, the double entry volume equation produced better predictive volume predictions than Gülen (1959)'s double entry volume equation and tables. The local single and double entry volume equations developed for Crimean pine forests in Turkey can provide more accurate predictions for tree volume.