engleski

SOME QUALITY CHARACTERISTICS OF FIR TREES (Abies alba, Mill) IN THE EDUCATIONAL-EXPERIMENTAL FOREST SITE ZALESINA, MANAGEMENT UNIT "BELEVINE"

This paper presents research results of some quality characteristics of fir trees (Abies alba, Mill) in selection forests in "Belevine" management unit, EEFS Zalesina. Research encompassed 1, 404 fir trees with dbh from 20 cm to 85 cm and heights from 12 m to 40 m. After felling and debranching, the timber volume of trees up to 7 cm diameter under and over bark was determined with the sectioning method. Timber assortments were processed and measured according to the Croatian standards for roundwood. Timber volume of trees to 7 cm diameter under and over bark, as well as the processed timber volume is shown in two-entry and one-entry tables. Bark volume ranges from 12.45 % to 10.67 %. The proportion of bark decreases from 21.8 % at 20 cm diameter to 7.4 % at 84 cm diameter according to the diameter of roundwood. The yield has values from 81.7 % to 83.0 % ; it decreases with an increase in dbh and rises with an increase in tree height. In the regressed assortment structure, sawlogs in quality class I have the highest values in the 42.5 cm diameter class (18.4 %), but sawlogs in quality class II have the highest value with the thinnest trees in the sample (36.2 %). The proportions of quality class III increase from 29.7 % to 42.4 % with a rise in dbh. The maximal proportion of mining timber is in the diameter class 22.5 cm (59.96 %), but it decreases to 0.51 % in the diameter class 77.5 cm. The proportions of pulpwood are under 8%. The maximal value of wood is found in the 52.5 cm diameter class.

fir tree; quality characteristics; timber volume; timber assortment; quality class

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