engleski

The Dynamics of the Vertical Development of Tree Crowns and Trunks in Homogeneous and Mixed Pedunculate Oak Stands in Croatia

The crown length is an important indicator of developmental stand conditions. An increase in the crown length increases its volume, as well as its assimilatory mechanism and production of tree substances, while the relationship between the trunk and the crown changes in favour of the crown. The share of the crown to the tree’s total height, in deciduous trees, is approximately 30 % and is a good indicator of forestry management and a prerequisite of good natural renewal. Observing the crown development as one of the stand structural elements is a point of interest for all foresters, especially in determining the time, intensity and duration of the sylviculture, as well as its growth. This paper shows the intensity of the vertical development of the tree crown and trunk in relation to the breast height diameter and the age of the stand, in addition to observing differences in the length of the tree crowns and trunks in homogeneous and mixed pedunculate oak stands. Research was undertaken in the associations of pedunculate oak and common hornbeam (Carpino betuli-Quercetum roboris Anić ex Rauš 1969) and the pedunculate oak and great green weed (Genisto elatae-Quercetum roboris Ht. 1938). For both associations fifty sample plots were chosen for investigation. The age categories were between 20 and 120 (140) years. Data processing was done in the same manner for all plots. Correlative and regressive analyse was carried for tree crowns and trunks length. The aim was to find a mathematical expression that reflects the spreading and variability of the data. Preliminary research that was carried out in homogeneous oak stands show that the share of crowns in the total tree length is uniform throughout all developmental stages, excluding regeneration, and is 45% of the tree height. Further more, the crown length increases as the diameter and the stand age increase up to the fertilisation period. Vertical development is most prominent in young stands, slower in middle aged stands and weak in old stands. The length of the trunk, as well as the tree diameter, is one element that influences the share of useful tree volume. The development of the trunk length of young trees is very intensive, then decreases and with the formation of the permanent crown ceases. Once the permanent crown is formed only the diameter will increase. A comparison of homogeneous oak stands to mixed ones, whose crown and trunk lengths are under the influence of subdominant common hornbeam storeys, will be a contribution to the understanding of the dynamics of the vertical development of tree crowns and trunks.

pedunculate oak (Quercus robur L); the vertical development of the crown; development of the trunk length.

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