Results of a 57-Year-Long Research on Variability of Wood Density of the Scots Pine (Pinus sylvestris L.) from Different Provenances in Poland

This research was conducted in the forests of Poland between 2019 and 2022. The aim was to study Scots pine provenances and compare the wood density variability among the various provenances growing on one experimental plot (in situ). The experiment was established in 1962 in the Zielonka Forest Division, Potasze Forest District. In 2019, five model trees from each provenance, which grew on the experimental plot, were chosen. In total, 40 trees were cut down, from which samples were collected in order to determine their wood density variability. The results indicate significant differences among the Scots pine provenances. It is not necessary to repeat it in situ. It appears that genetic factors highly impact the process of forming the wood density of the Scots pine. The research revealed that the best-quality wood, as far as wood density is concerned, comes from the Zielonka provenance, whereas the lowest relative density comes from the Gleboki Brod provenance. Both the provenance experiments and the analyses allowed for the selection of the research material that indicated the best genetic properties. Moreover, the research provides analytical tools that will allow for the prediction of the Scots pine provenance with the best quality together with high resistance to exogenous factors, such as habitat conditions, which can be vital to improving wood quality.