Developing single and double tree volume equations for scots pine trees: A case study in Başçatak (Akdağmadeni) forests

In this study, single entry and double entry tree volume equations have been constructed to model individual tree volume of Scots Pine (Pinus sylvestris L.) trees located in the Başçatak Plannig Unit, Akdağmadeni Forest Enterprise, Kayseri Forest District Directorate, in which has great importance in terms of both forest areas and economical value. The six functions for single entry volume equations and twenty-seven functions for double entry volume equations were compared by the fitting performance criteria. The best predictive single entry and double entry volume equation accounted for 93.1% and 98.10 % of the total variance at volume prediction, respectively. The best predictive single and double entry volume equations were decided to be appropriate for the studied Scots pine trees by testing independent data. Percentage Absolute Mean Error, which represents the percentage of error when the volume equation developed is used in the estimation of a single tree, were calculated as 13.8811% for single entry equation and 7.1573% for double entry equation. However, the percentage total error representing the percentage of error in the case of the volume equation being used in the estimation of the volume in a large number of trees was calculated as -0.3975% for single entry volume equation and -5.27x10-14% for double entry volume equation. The best predictive single-and double-entry tree volume equations were validated to the stands, which the study data were obtained in the stands, by using "Equivalence" test, a new method in the forestry literature, and these single-and double-entry tree equations were found to be suitable for the Scots pine forests in Başçatak Plannig Unit.