Development of tree volume equations for natural brutian pine (Pinus brutia Ten.) stands in Ka？ District

Brutian pine (Pinus brutia Ten.) forests are economically and ecologically one of the most important forests in Turkey. The one of the essential building blocks in forest growth and yield prediction models is the equations for estimating individual tree volume. Individual tree volume estimations can be used to tree and stand volume estimations and to any merchantable limit of this volume, forest management plans arrangement, to projections of forest products industries, and to estimations of biomass and carbon budgets. In this study, tree volume equations were developed for brutian pine stands in Ka？ Region. In this study, 517 sample trees destructively measured and then these trees are randomly divided into two groups as model development data and validation data. Nineteen regression models tested in this study. The tested models were compared using five performance criteria (average absolute residuals, root mean square error, coefficient of determination, maximum absolute error, and, Akaike Information criteria) for model development and validation dataset. Accordingly relative rank of models, while the best volume equation is Model 4, the worst equation is Model 3 for tree volume predictions. The results of Model 4 are compared with results of the other volume equations for model validation dataset. The proposed model performed better than the other models for volume estimations. The obtained results showed that, more accurate volume estimations can be obtained using model 4 for natural brutian pine stands of Ka？ District