Impact of a fresh broadleaved forest site and fresh mixed broadleaved forest site on selected parameters and ratios of silver birch (Betula pendula Roth.) wood fibre structure

The variability of selected ratios characterising the dimensions and shape of silver birch wood fibres was determined based on the site where the trees grow. Two sampling areas were selected, located in the Biała Podlaska Forest District in eastern Poland. Samples for testing were taken from trees approx. 45–50 years old, growing on a fresh broadleaved forest site and on a fresh mixed broadleaved forest site. On these two sites, silver birch occurs most widely as a dominant species, both in terms of stand area and volume, in Poland. A statistical analysis was performed of selected parameters of the wood fibre structure such as length, width, lumen and cell wall thickness, as well as of the wood fibre structure ratios belonging to the basic properties of fibrous pulp: the felting power, flexibility ratio, coefficient of rigidity, Runkel and Mühlsteph ratios, as well as the compactness index. It was demonstrated that the site from which birch material originates has a significant impact on the average values of: fibre length, lumen, flexibility ratio, and the coefficient of rigidity, as well as the Runkel and Mühlsteph ratios. However, analyses did not prove any major impact of the site on the average values of: fibre width and wall thickness, the felting power or the compactness index of silver birch wood