Model of stem taper of Scots pine (Pinus sylvestris) in the Kostroma region

Models of the stem taper have become widespread in forestry research. Models of the stem taper based on the equations of the stem taper are capable of determining with sufficient accuracy the assortment potential of forest stands. For the Kostroma region, no work has previously been carried out aimed at modeling the stem taper of trunks. Therefore, the goal of the study was to search and justify models of the stem taper of a tree trunk with one equation that most correctly describe the change in tree diameter with height in Scots pine stands growing in the Kostroma region. As experimental data, 10064 measurements of the diameter of 692 pine trees were obtained. To carry out the analysis, 19 models of tree stem taper with one equation were selected. Calculations were carried out in the Python environment. The calculated values of quality metrics, graphical analysis of residuals and errors made it possible to establish that the four-parameter model most adequately describes of the stem taper of pine forest stands in the Kostroma region. The stem diameter predicted using the model at any height makes it possible to analyze the assortment structure without resorting to tree felling. Further research is required aimed at developing standards for the assortment structure of trunks based on the proposed stem taper model.