Data from stem analysis of 397 dominant trees (198 Scots pine and 199 Oriental beech) were used to evaluate dynamic base-age invariant site index models derived from Bertalanffy–Richards, Hossfeld, and Lundqvist–Korf functions with the generalized algebraic difference approach (GADA) for mixed Scots pine (Pinus sylvestris L.) and Oriental beech (Fagus orientalis Lipsky) stands. | Turkish Journal of Agriculture and Forestry Turk J Agric For (2014) 38: 134-147 © TÜBİTAK doi: Research Article Dynamic base-age invariant site index models based on generalized algebraic difference approach for mixed Scots pine (Pinus sylvestris L.) and Oriental beech (Fagus orientalis Lipsky) stands 1, 2 3 İlker ERCANLI *, Aydın KAHRİMAN , Hakkı YAVUZ Faculty of Forestry, Çankırı Karatekin University, Çankırı, Turkey 2 Faculty of Forestry, Artvin Çoruh University, Artvin Turkey 3 Faculty of Forestry, Karadeniz Technical University, Trabzon, Turkey 1 Received: Accepted: Published Online: Printed: Abstract: Data from stem analysis of 397 dominant trees (198 Scots pine and 199 Oriental beech) were used to evaluate dynamic base-age invariant site index models derived from Bertalanffy–Richards, Hossfeld, and Lundqvist–Korf functions with the generalized algebraic difference approach (GADA) for mixed Scots pine (Pinus sylvestris L.) and Oriental beech (Fagus orientalis Lipsky) stands. – These functions were compared with respect to residuals of these models; specifically, the evaluation criteria were bias (E ), root mean square error (RMSE), absolute mean error (AME), adjusted coefficient of determination (R2adj), and Akaike information criterion. The best results were obtained with generalized algebraic difference equations derived from the base models of Bertalanffy–Richards for Oriental beech and Hossfeld for Scots pine. These selected models accounted for 95%–96% of the total variance in height–age relationships in dominant trees with bias of and , RMSE of and , AME of and , and AIC of and for Scots pine and Oriental beech, respectively. These dynamic base-age invariant site index models for the 2 tree species presented more effective and accurate polymorphic site index curves with .
