The article presents the results of a so far most extensive study on the effect of tree age on variation of the chemical structure of silver birch wood carried out in Poland. Field studies took place in 12 forestry districts distributed throughout the country. In each district, study sites were selected with stands aged approximately 30, 50, and 70 years in fresh broadleaved forest habitats, as well as in five districts in fresh mixed broadleaved forest habitats. Analyses were made of the contents of substances soluble in cold and hot water, ethanol and 1% NaOH, as well as the contents of cellulose, lignin, pentosans and ash, and the pH, of wood from 306 silver birch trees. Tree age was shown to have a significant effect on the contents of cellulose, pentosans, ash, and substances soluble in 1% NaOH. In the case of the other characteristics, age was found to have no significant effect. The cellulose content was lowest in 30-year-old stands and increased with tree age. Similar observations were made regarding ash content. Contents of pentosans and substances soluble in 1% NaOH were highest in the wood of the youngest trees. Since birch wood is used by the pulp and paper, board and energy industries, the knowledge of its chemical composition, depending on the age of the trees, can be of potential practical importance for its further application.

We report on the most extensive study to date in Poland concerning the variability in the chemical composition of silver birch (Betula pendula Roth.) wood depending on the forest habitat type and the location of the forest stand. The research was carried out in 12 forest districts, on two habitat types where silver birch forest stands predominate in respect of coverage area and merchantable volume. Chemical composition analysis was performed on 51 samples from 306 test trees aged approximately 30, 50 and 70 years. In the examined sample material, the sum of the main chemical components for individual locations varied from 89.26 to 91.57%. The content of substances soluble in water and ethanol ranged from 2.30 to 4.03%, and the ash content was measured at between 0.09 and 0.25%. The results showed that the location had a significant influence on the contents of substances soluble in cold water (p = 0.0015), hot water (p = 0.0005), ethanol (p < 0.0001) and 1% NaOH (p = 0.0014), as well as on the contents of cellulose (p = 0.04), lignin (p = 0.002), pentosans (p = 0.04) and ash (p < 0.0001) and on the pH value (p < 0.0001). Notable influence of location on the contents of secondary constituents of birch wood, especially those extractable with water and ethanol, was recorded for the test plots in north-eastern Poland. The obtained results may form a basis for assessment of the industrial utility of birch wood, as well as the optimisation of traditional methods of utilisation and the development of new such methods that are ecological and sustainable.

The most extensive study to be carried out in Poland, and one of only a few worldwide, regarding the influence of location, tree age and forest habitat type on the basic fuel properties of silver birch (Betula pendula Roth.) wood was conducted in 12 Forestry Districts of the Polish State Forests. The field study included trees in three age groups of approximately 30, 50 and 70 years. The research was carried out in a fresh broadleaved forest (FBF) habitat type, where in Poland silver birch stands predominate in respect of coverage area and merchantable volume. Additionally, for five selected Forestry Districts, a comparative study was conducted in a fresh mixed broadleaved forest (FMBF), the second most important habitat of this tree species. A total of 306 test trees were examined. For every sample, calorific value and contents of ash, carbon, hydrogen, nitrogen, sulphur and chlorine were determined. The results indicated a statistically significant influence of location on the calorific value (p = 0.0001) and on the contents of ash (p < 0.0001), carbon (p < 0.0001), hydrogen (p < 0.0001), nitrogen (p < 0.0001) and chlorine (p < 0.0001) in the analysed wood. Moreover, statistically significant differences were observed between values of ash content (p = 0.046) and of calorific value (p = 0.0026) depending on the forest habitat type. Tree age was found to have no significant influence on the calorific value of silver birch wood.

This work contains the preliminary results of research into the technical quality of the wood from Scots pine trees of diverse genetic origin, grown on an experimental plot at the Forest Experimental Station in Rogów. The following are the parent stands, numbered: 5 (the Tucholskie Forest 130 m a.s.l.), 7 (the Napiwodzko–Ramuckie Forest 145 m a.s.l.), 10 (the Piska Forest 145 m a.s.l.), 12 (the Biała Forest 95 m a.s.l.), 13 (the Namysłowsko–Ostrzeszowskie Forest 190 m a.s.l.), 15 (the Knyszyńska Forest 165 m a.s.l.), and 16 (the Nowotarskie Forest 590 m a.s.l.). The tested wood was obtained in 2018 from trees aged 52 years. The research material came from 100 trees in total. After felling, two logs approximately 0.5 m in length were cut from each tree. The height on the tree from which the material was taken ranged from breast height (1.3 m) to approximately 2.5 m. Next, planks were cut from the logs in a north–south direction; these were precisely described and then left to season. The work included the measurement and statistical analysis of one physical property, wood density (kg/m³), and of the following mechanical properties: compressive strength along the fibres, Rc₁₂ (MPa); static bending strength, Rg₁₂ (MPa); modulus of elasticity under static bending, Eg₁₂ (MPa); and indices of strength quality of the tested mechanical properties, JRc₁₂, JRg₁₂, and JEg₁₂ (km). The origin of the logs was shown to have a significant influence on wood density, compressive strength, static bending strength, and modulus of elasticity under static bending. The highest mean density was found for trees originating from stand 10 (537 kg/m³). The highest values of compressive strength were obtained for trees originating from stands 5 (45 MPa), and the highest static bending strength and modulus of elasticity under static bending were obtained for trees originating from stand 12 (102 and 9825 MPa, respectively).

This work presents the findings of a study concerning variability in the basic density of silver birch ( Roth) wood, depending on the geographical location of tree stands, the age and thickness of the trees, the forest habitat type, and interactions between some of these factors. The study was carried out on wood from trees aged approximately 30, 50 and 70 years in 12 forest districts located throughout Poland. In total 4777 wood samples, taken from 306 trees from 51 test plots, were measured. The location, the age of the trees, the thickness of the trees and the forest habitat type, as well as interactions between these factors, proved to have a significant influence on the basic density of silver birch wood. The highest mean values of the basic density of the birch wood were found in Sokołów forest district on the FBF habitat type (549 kg m) and in Giżycko forest district on the FMBF habitat type (548 kg m). For the entire set of examined material, the average values of the basic density of wood increase with tree age. For the examined material originating in FBF and FMBF habitats the average values of basic density showed no significant differences; however, in the cases of the forest districts of Giżycko, Łobez and Rudziniec, significant differences in the analysed property were observed.Betula pendula –3 –3

The properties of black cherry mature wood (Prunus serotina Ehrh.) and its susceptibility to fungal decay were studied in the invaded range of the species on six trees aged between 39 and 47 years old growing in poor, acidic soils with varying levels of moisture and organic carbon and nitrogen content. Wood from trees that grew in wetter and richer soil had better physical properties. Of the 95 parameters analyzed, 80 showed significant differences in favor of this wood. These differences included wider rings that averaged 3.25 mm, a higher density of 662.71 kg/m³ at 12% humidity, and 1.5 times higher content of extractives. Gas chromatography with mass spectrometry revealed the presence of 44 extractives. Out of these, six had antifungal properties and were found in the wood of trees grown in richer soil, corresponding to 62.93% of the peaks area of all identified substances. Only three were found in trees grown in poorer soil, corresponding to 8.68% of the peaks area respectively. The wood of trees grown in more fertile soil was also less prone to fungal decay, which was generally low. Only Trametes versicolor caused a mass loss of more than 10% of the wood in both sites out of the four basidiomycete species tested. The results indicate that even slight variations in soil fertility and moisture can benefit black cherry, leading to differences in wood features and properties in its exotic range.