Acta Scientiarum Polonorum
Silvarum Colendarum Ratio et Industria Lignaria

The study presents the results of an empirical assessment of the accuracy of volume estimation methods used for Scots pine (Pinus sylvestris L.) logs from the Biłgoraj Forest District. The aim of the research was to determine the magnitude of systematic error associated with commonly applied methods of estimating the volume of short and long logs, using the sectional method as the reference. The research material consisted of 105 sample trees from three forest site types (Bśw, Bw, BMw), from which logs of various lengths were virtually obtained. Using linear mixed-effects models, it was found that the commonly applied volume estimation routines underestimate the volume of long logs by an average of 8.54%, while the volume of short logs is underestimated by an average of 8.10%. The key factors affecting the magnitude of the error were the adopted volume estimation method and length variant, the position of the piece along the stem (presence of the butt section), as well as the assumed normative bark thickness and rounding procedures. It was estimated that these errors generate financial losses of approximately PLN 2.37 million annually at the forest district level. The obtained results suggest the need for further revisions of national standards for timber volume estimation.