engleski

Crown Shape Dynamics in Managed Stands of Pedunculate Oak (Quercus robur L.) and Common Hornbeam (Carpinus betulus L.)

Species-specific crown shape, expressed as a relation of crown diameter and crown length (D lk-1) changes during the tree lifetime in concordance with the ecological constitution of the species, productive capacities of the stand, and implemented management activities. In young stands (at the time of maximum current annual height increment) the crown is usually elongated, and becomes shorter as the stand reaches maturity. This is more evident in deciduous tree species. We investigated average crown shapes (models) of pedunculate oak and common hornbeam trees, as well as their change over time and with respect to diameter at breast height (DBH). Results are based on the measurements of 2, 235 trees from 47 permanent experimental plots with a total area of 33.45 ha. The plots are situated in two-layered, even-aged pedunculate oak and common hornbeam stands of different age classes. Pedunculate oak trees develop crowns with maximum width roughly between one half and one third of the upper crown length. In more open canopies (as a result of management activities or degraded stand conditions) height of the maximum crown width decreases and the relative length of the sun-exposed crown increases. Common hornbeam trees constitute the lower layer of the canopy with the maximum crown width in the lower third of the crown length. Length of the sun-exposed crown in common hornbeam trees is always greater than half of the total crown length. Knowledge about the development of crown shape in oak and hornbeam trees across stands of different age classes is indispensable for further calculations of crown volume. These calculations are widely used in diverse models of energy and material exchange within forest ecosystems and between forest ecosystems and the larger environment.

crown shape; pedunculate oak; common hornbeam; managed stands; tree age

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