Parametryczna i nieparametryczna aproksymacja rozkładów pierśnic w drzewostanach o różnej budowie pionowej

The objectives of this study are (i) by using selected parametric models and the kernel density estimator to compare the accuracy of approximation of the empirical DBH distributions in stands of different vertical structure as well as the approximation accuracy in the empirical DBH data sets characterised by either average, or small or large differences in the number of DBHs in the neighbouring DBH classes, and (ii) to assess the significance of differences between the selected parametric models and the kernel density estimator. Sampling was carried out in the Świętokrzyski National Park (forest sub-districts: Święta Katarzyna and Święty Krzyż). In the stands of different vertical structure the irregular DBH empirical distributions require reducing the bandwidth of the kernel density estimator. In one-storied, two-storied and selection stands one should employ parametric models, using the kernel density estimator only for the preliminary approximations. However, when approximating the empirical DBH distributions in many-storied stands the kernel density estimation can be much more useful.