Revitalisation of a beech stand - ecological necessity and potential of biomass utilisation

The structure and growth of beech trees was analysed in the unmanaged beech stand with admixtures of sessile oak, lime and hornbeam on Fruška Gora, based on two periodic measurements. The first measurement was performed at the stand age of 97 years, and the second at the age of 105 years. The 97-year old stand was characterised by significant sizes of growth elements per hectare (N=208, G=32.64 m 2 ∙ha-1 , V=467.62 m 3 ∙ha-1 ). In both measurements, there were 153 beech trees per hectare, which in total structure accounts for 75% per tree number, 82% per volume and 85% per current volume increment. The spontaneous stand development resulted in the increased phyto-sociological weakening of trees which was, during the study period, reflected in the following features of beech trees which were the subject of the research in present study. In both measurements, upper storey beech trees accounted for 94 % per tree number and for 98% of volume. During the first measurement, the trees with freely formed and reduced crown by less than 25% of the crown perimeter, accounted for 22% and 32% of volume, and during the second measurement, they accounted for 8.5% per tree number and 14.3% of volume. The trees with multiple-sided reduced crowns, during the first measurement accounted for 26 % and for 16% of volume, and during the second measurement they accounted for 50% and 35% of volume. During the study period, the average annual increase in basal area, volume, above-ground oven-dry biomass and carbon quantity in beech trees with freely formed and reduced crowns by less than 25% of the crown perimeter, increased by 88-94%, and in the most prosperous trees in the silvicultural sense by 49-55%, compared to the stand average. Compared to the stand average, lower average annual increase in the above increments by 32- 33% were achieved by the unprosperous trees in the silvicultural sense, which justifies their removal from the stand in the aim of the higher increment potential of the most prosperous trees in the silvicultural sense.