Developing single and double tree volume equations for crimean pine [Pinus nigra Arnold. subsp. pallasiana (Lamb.) Holmboe] in Yozgat forest district enterprise

Individual tree standing volume composed most significant part of forest capital in forest enterprise and the tree volume equations and tables which can be commonly used for predicting tree volume is important to forest management practices. In this study, the single and double entry volume equations were developed for Crimean Pine [Pinus nigra Arnold. subsp. pallasiana (Lamb.) Holmboe] trees located inYozgat 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 91.5 % of the coefficient of determination and double entry volume equation with 92.4 % 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. The single and double entry volume equationstaht are developed in this study are statistically successful and provide accomplished volume predictions for Crimean pine trees located in Yozgat forests. The local single and double entry volume equations developed for Crimean pine forests in Turkey can provide more accurate predictions for tree volume.