Stojnić Srđan, PhD

This study quantified the physical and mechanical properties of sycamore maple (Acer pseudoplatanus L.) as a basis for assessing wood quality. The physical properties of oven-dry density, density at 12% MC, green density, basic density, longitudinal, radial, tangential and volumetric shrinkages were tested and the mechanical properties of bending strength, modulus of elasticity at bending, compression strength parallel to grain and compression strength in radial and tangential direction as well as of Brinell hardness on the cross, radial, and tangential section were determined. Five sycamore maple trees from Medvednica region were selected for the purposes of this research. The results were compared with known literature data on sycamore maple wood, beech wood from the same sight, and beech wood from Gorski Kotar region. For a better understanding of sycamore maple physiology, as well as for assessing the quality of wood products, the distribution of wood properties within the tree radius, from pith to bark, was investigated. There was a general bell shaped distribution, in the radial direction, in wood density, and mechanical properties of sycamore maple wood. Shrinkages decreased from pith to bark, except for tangential shrinkage with bell shaped pattern. All investigated wood densities of sycamore maple from Medvednica were similar to the findings of studies known in literature, as well as shrinkages, except for the lower longitudinal shrinkage. Investigated mechanical properties of sycamore maple wood were similar to the findings of studies known in literature, except for the lower bending strength and modulus of elasticity (MOE). Investigated sycamore maple indicated better dimensional stability than beech wood from two locations in the region, although it did not match the beech wood regarding mechanical properties, especially wood hardness.

In this paper, the variability of morphological (stem height, stem basal diameter, proportion of pith, wood and bark) and wood anatomical characteristics (fiber length, fiber diameter, fiber lumen diamater, double cell-wall thickness, vessel diameter, wood rays width and height) of three Salix alba clones (B-44, 347 and NS 73/6) and one Salix viminalis clone both in the control plot and in the site contaminated with a mixture of heavy metals (As, Cd, Cr, Cu, Ni, Pb) was investigated. The observed results showed that individuals of all four clones had significantly higher average values of stem height and stem basal diameter at the control plot compared to the polluted site. As for the proportion of pith, bark and wood, heavy metals caused an increase in the share of pith and a decrease in the share of bark and wood in all clones with the exception of clone NS 73/6. The analysis of wood fiber dimensions showed that the values of all parameters were higher at the control site with the exception of fiber lumen diameter where higher values were observed for clones B-44 and NS 73/6 at the polluted site. Higher values of vessel diameter were recorded for all clones at the control plot, while wood rays width of all individuals was greater at the contaminated site. Regarding the wood rays height, only Salix viminalis showed higher value at the polluted site. These results confirmed that pollution-induced heavy metal stress significantly altered the morphological and wood anatomical characteristics of all researched clones and that it may affect their utility properties.