Developing some diameter distribution models for stands located Kestel forest unit directorate, Bursa forest district directorate

Diameter distributions are a vital stand feature that exhibits forest structures and dynamics. Informations about diameter distributions of a forest stand are used to obtain detailed estimations related to stand structure and range of products in process of forest planning. In this study, the diameter distributions have been established with 3-parameters Weibull function depending on 398 sample plots obtained from Kestel Forest Unit Diroctorate, Bursa Forest district Directorate and different estimation equations based on various percentages were compered in estimation of parameters of Weibull function. In this study, a total of different six estimation methods consisted of maximum probability method and different five equations based on the values corresponding to the 25th, 31th, 50th, 63rd and 95th percentiles of diameter distribution were evaluated. According to eror index developed by Reynolds et al. (1988), when parameter esmation methods are compered, parameter esmation method that has 2.52 score including 31th and 63rd percentiles of diameter distribution have been determined as best method in fitting of diameter distributions. In addition, it was concluded that Weibull function that was established by using 31th and 63rd percentiles of diameter distribution is appropriate for 384 of 398 sample plots with 95% confidence. When the parameters of Weibull function and stand characteristic including different mixtures of tree species, stand diameter class and stand crown closure were compared, whereas important differences were determined for different mixtures of tree species, stand diameter class, it wasn't determined for crown closure. According to the predicted number of trees by Weibull function, mean error ratio was computed as 8%. While diameter distribution models give detailed informations at level of diamater class, stand models and yield tables give informations (stand volume, basal area and number of tree) at level of stand. In this way, detailed estimations are basic for forest management and silviculture and serve to forecast range of products provided from a forest stand.