In the case of Scots pine (Pinus sylvestris L.), anatomical differences between the sapwood and heartwood were researched, the content of extractives in the sapwood and heartwood defined, hygroscopicity of sapwood and heartwood studied, so as the relationship between the content of extractives and sorption properties. Research was carried out on 6 test trees. Anatomical investigations were performed using the classic light-field microscopy. Investigation of samples for determination of dimensional stability and sorption properties was held by balancing in the glass-air condition chambers. Samples were extracted for chemical analysis using cyclohexane, and the mixture of acetone and water, and the proportion of total phenols determined by UV/VIS spectrophotometry. The differences between the sapwood and heartwood were in the resin canals, in the lumens of axial tracheids with strips of band as well as differences in parenchymal cells and bordered pits. The part of exstractives in the heartwood was higher than in the sapwood, and indicated on phenomenon of compound with phenolic character, either lignin or other phenolic compounds. Investigations of the sapwood and heartwood did not show statistically significant differences in the density in the absolutely dry state, at the point of saturation of cell walls, in the volume shrinkage, and not in the coefficient of swelling in the tangential direction. Heartwood formation processes caused statistically significant differences between the sapwood and heartwood in the transverse anisotropy, differential swell in the radial and tangential direction, in the coefficient of swelling in the radial direction and the sorption quotient. Humidity of sapwood was 90 %, and humidity of heartwood 24 %. Investigation, carried out in the case of a Scots pine, shows that the changes occurring in the wood in the process of heartwood formation have effect on the anatomical and chemical structure of wood, which hereinafter also impacts the specific sorption properties of wood.
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