Impact of location and forest habitat type on values of selected parameters and structural indices of wood fibres of silver birch (Betula pendula Roth.) in Poland

The aim of this study was to examine the variation of selected parameters and structural indicators of the Betula pendula Roth. fibres depending on the geographical location of the forest stand and forest habitat type. It is the most extensive study to date in Poland concerning the variability of silver birch fibre structure. The research was carried out in 16 forest districts on three habitat types, where silver birch stands predominate in respect of coverage area and merchantable volume. Analysis was performed on 69 samples from 414 trees aged 30, 50, and 70. The following parameters and structural indicators characterise silver birch fibres: length 1316 μm, width 24.20 μm, lumen 11.91 μm, wall thickness 6.14 μm, slenderness ratio 55.49, Runkel ratio 1.14, rigidity index 25.63, Mühlsteph’s index 0.754, flexibility coefficient 0.487, solids index 0.35. The results showed that location had a significant effect on all the parameters studied. For two locations in the south–western and north–eastern regions of Poland where fibres from three habitat types were studied, it was found that fibre width and rigidity index were influenced only by location; fibre length, lumen width, Runkel ratio, Mühlsteph’s index, and flexibility coefficient were influenced only by habitat; both location and habitat influenced wall thickness, slenderness ratio, and solids index. The parameters and structural indicators of birch fibres do not exhibit regular dependences on habitat richness. Birch fibres are suitable for a wide range of applications, especially in the implementation of innovative ways of using wood.