Developing some diameter distribution models for maritime pine plantations stands located in Sinop forest management

This study aims to model the diameter distributions within Coastal Pine (Pinus pinaster) plantation stands in the Sinop Central Forest Management Chiefdom. The research utilized tree data from 202 temporary sample plots, applying the three-parameter Weibull probability density function for diameter distribution estimation. Eight different methods (Maximum Likelihood, moment-based, percentile-based, and hybrid approaches) for estimating Weibull parameters were comparatively assessed, and model performance was analyzed using the Relative Ranking Method. Model evaluation identified the moment method (Method 3) incorporating the mean diameter of basal area (Dg) and the variance of diameters as the most successful estimation approach. Key performance indicators for this model were determined as R2= 0.701, RMSE=57.486 stems/ha, and AIC=9590. Furthermore, the statistical adequacy of the best model's predictions was confirmed by the Kolmogorov-Smirnov test, showing statistical suitability for of the sample plots.