Acta Scientiarum Polonorum
Silvarum Colendarum Ratio et Industria Lignaria

In this study 13 functions describing the dependence between diameter at breast height and tree height were tested to determine stand volumes as affected by the changes in the forest management in the Sudeten Mts. Tree measurements were recorded in two sample plots in the years 2013 and 2015. The functions were tested on data concerning spruce, beech, sycamore maple and fir. Function parameters were determined through transformation of equations to the linear or polynomial form and solution of the system of normal equations, as well as the Levenberg-Marquardt iterative method applied in the Statistica 12 software package. Fitting of function curves to the data was better when applying the iterative method. The best fit was found for the graph of the 2nd degree parabola. A good fit was obtained when using the functions proposed by Korsuň (1935)   (H = exp(a + b · ln(D) + c · ln2(D)) and by Prodan (1951) (H – 1.3 = D2/(a + b · D + c · D2)). Goodness of fit for the other tested functions was much lower. Despite a very good fit, graphs of the 2nd degree parabola and the Korsuň function do not meet all the postulates of dendrometry imposed on curves of tree height. For this reason the function proposed by Prodan was selected for practical use.