Devolopment of stem taper model for maritime pine plantations in Istanbul Sariyer region

Maritime pine (Pinus pinaster Ait.) is one of the most important tree species in Turkey for indtustriel plantations establisment. In this study, stem taper models were develeped for maritime pine plantations in İstanbul-Sarıyer Region. For this aim, some taper models belonging to two different taper model groups (segmented and variable-form) were evaluated. In this frame, totally 194 destructively sampled trees was used. These equations were fitted with ordinary nonlinear least squares method. We incorporated a second-order continuous-time autoregressi error structure to model (CAR(L)) o addresses of autocorrelation problem and used condition numbers to detect presence of multicollinearity. To evaluate predictie evaluated of the taper models were predictie eveluated in terms of the diameter at specified height, height at any given diamater, merchantable volume, and total stem volume estimations. For this aim, we used five different evaluation criteria. As a result of evaluations, the variable-form model of Lee et al. (2003) is the best model using ranking system proposed by Poudel ve Cao (2013). Accuracy and reliable tree diameter and volume estimations can be done using this taper model for maritime pine plantations in İstanbul-Sariyer Region. On the other hand, according to model relative ranking, there is no big difference between Fang et al. (2000) and Lee et al. (2003) models in terms of predicting capacitiy of the models. Therefore, Fang et al. (2000)'s taper model can be use for estimating diamatr and volume. This model has the additional advantage that it is comptible with both a total volume equation and a merchantable volume equation, which allows for rapid volume prediction.