Maksymchyk R. Intraspecific differentiation of Abies alba Mill. on the wood structure in the forest conditions of the Bukovynian Carpathians

In the review of scientific literature, the domestic and foreign knowledge about the historical and economic aspects of the silviculture of silver fir and its dendrological differences in Europe were summarized. The point was emphasized on the silvicultural properties of fir stands in the Ukrainian Carpathians in terms of their typological and altitude-ecological distribution. The question of the peculiarities of the formation of physical and mechanical properties of wood within the stem and in different forest vegetation conditions of the natural growth area was revealed. The analysis of many scientific works states that forestry features of the growth of silver fir with wavy-relief wood formations and scientific issues of intraspecific differentiation by wood structure and peculiarities of formation of physical and mechanical properties in forest vegetation conditions of Bukovynian Carpathians have not been studied. To study the structural differences of the stemwood of silver fir, the fir stands growing in the wet spruce-beech fir type were selected. The research covered 11 trial plots, where 12 model trees were cut down to determine the physical and mechanical properties of straight-grained and wave-grained wood, and 50 trees with wavy-relief stemwood formations were selected to determine morphological differences of stems and 120 trees for dating annual rings. The scientific novelty of the dissertation work is that for the first time: the morphological forma of the silver fir with the straight-grained wood in the forest vegetation of the Ukrainian Carpathians was distinguished; the description of morphological features of trees with wavy-relief stemwood formations was carried out and the age range of the beginning of their formation was established; indicators of annual growth, wood density, swelling anisotropy, speed of sound in the longitudinal direction, attenuation coefficient, static and dynamic modulus of elasticity of wave-grained wood were determined; a correlation-regression analysis of the relationship between the quality characteristics of silver fir wood with a typical and wave-grained structure was done. There were acquired the further development of knowledge about the physical and mechanical properties of straight-grained silver fir wood within the radius and height of the stem; regularities of the doctrine of the basic principles of individual and population selection of the main forest-forming species; wood science principles on the regularities of formation of wood quality features of targeted purpose and their visual diagnosis through the number of annual rings in 1 cm; practical information on the round timber grading and the allocation of the quality class "decorative wood". The quality assessment of the growing tree was aimed at the selection of the round timber with desired stemwood properties of silver fir. The morphological markers of trees with wavy-grained wood include their width and depth, as well as the length of round timber with wavy-relief stemwood formations. The formation of anomalous stemwood was due to the indicators of the macrostructure: the width of the annual ring, the percentage of early and late wood in the annual ring. The natural differentiation of silver fir in the wood structure should be associated with an abrupt sharp change in microclimatic conditions of the growth and altitude and environmental factors. According to the results of one-factor analysis of variance of the width of the annual ring of silver fir wood, statistically significant (p <0.05) structural deviations between trees with straight-grained and wave-grained wood were found. The average values of annual growth in trees with wavy-relief stemwood formations were ranged from 3.98 to 5.74 mm, and in trees with a typical structure - from 2.36 to 3.53 mm. A similar trend of changes in macrostructure indicators was found for the width of the early- and latewood in the annual ring. There was an increase of the wood density in trees with straight-grained wood with a rise of the number of annual rings in 1 cm. The values of the correlation coefficient between the number of annual rings in 1 cm and different types of the wood density in stemwood with the straight-grained wood were ranged from 0.761 to 0.830. High correlation value was also observed between wood density, dynamic and static modulus of elasticity of wood. Based on the results of the study of intraspecific differentiation of silver fir on the wood structure, it was recommended for the round timber grading to establish the quality class of silver fir with decorative wood and to mark it "ABA-d". The generalized statistical data of physical and mechanical properties of straight- and wave-grained stemwood of silver fir in the conditions of Bukovynian Carpathians are addressed for logging of stemwood with desired wood properties and with the decorative wood texture.