CALORIFIC VALUE OF THE MAIN FRACTIONS OF ABOVE-GROUND BIOMASS FOR BEECH (FAGUS SYLVATICA L.), SESSILE OAK (QUERCUS PETRAEA (MATT.) LIEBL.) AND HORNBEAM (CARPINUS BETULUS L.)

In this article the results of the research focused on the calorific value capacity in the dry matter of above-ground biomass of beech, sessile oak and hornbeam are presented. For each tree species, 5-6 trees were felled and biomass samples were taken. From the lower, middle and crown part of the trunks, a disc of wood with bark was cut off and also a sample of branches (small-wood) was taken from crowns. On the discs, the bark was separated from the wood. The calorific value content was determined from all samples and fractions (wood, bark, small-wood). The differences in the calorific value among the fractions, their position on the trunk and tree species were investigated by an analysis of variance and a t-test. The biggest differences are between wood and bark. The bark has lower values of calorific value than wood, by 1,000-1,700 J g(-1). Coniferous tree species have higher calorific value by 600-900 J g(-1) (3-4%) for wood; 1,000-1,400 J g(-1) (5-7%) for small-wood and 2,400-2,700 J g(-1) (13-15%) for bark compared to deciduous species.