Variation of Selected Macrostructure Features and Density Wood of the European Spruce (Picea abies (L.) Karst.) in the Cross-Section of Trees over 90-Years-Old in Poland

Abstract

In the present study, the following features were investigated: the variability of selected macrostructure features (width of the annual growth ring and share of latewood) and wood density of the European spruce (Picea abies (L.) Karst.) in a cross-section of the trunk. The study was conducted in locations of the northeastern range (12 research plots) and the southwestern range (20 research plots) of spruce in Poland. On the testing plots, Pressler drill borehole samples were taken from 15 selected trees. Then, the borehole samples were divided into 2 cm long sections and, for each section, the average width of the annual growth ring, the average share of latewood, and the relative wood density were calculated. In conclusion, it was found that the width of the annual growth rings in the tested material was increasing constantly from the outer circumference (the perimeter) of the trunk towards the pith. The greatest share of latewood was found not only in the perimeter zones of the tree trunk but also in the zones close to the pith. It was also discovered that the highest wood densities occur in the perimeter zones, and that these densities decrease towards the pith. It was only in the sections next to the pith that an increase in wood density was noted. Having analysed the relationships between the examined features, it can be concluded that the width of annual growth rings affects both the share of latewood and the wood density. The aforementioned were negative correlations, whereas the increase in the share of latewood also impacts the increase in wood density and was determined to have a positive correlation.