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M. Prka: POJAVNOST NEPRAVE SRŽI KOD BUKOVIH STABALA I TEHNIČKE BUKOVE OBLOVINE ... Šumarski list br. 9 10. CXXVII (2003). 4d7-474 Pranjić,A. 1986: Šumarska biometrika; Sveučilište fakultet, Zagreb, str. 2-22. u Zagrebu, Šumarski fakultet, Zagreb. Hrvatske norme proizvoda iskorištavanja Šuma; II iz- Prka, M. 2001: Udio i kakvoća šumskih drvnih sorti- danje, Državni zavod za normizaciju i mjeriteljmenata u oplodnim sječama bukovih sastojina stvo, Zagreb, 1995. Bjelovarske Bilogore, Sveučilište u Zagrebu, Hrvatska norma Oblo drvo listača - Razvrstavanje po Šumarski fakultet, Zagreb, str. 74-82. kakvoći -1 dio: Hrast i bukva (EN 1316-1:1997); Tomaševski , S. 1958: Učešće i raspored neprave I izdanje, Državni zavod za normizaciju i mjerisrži kod bukovih stabala u G. J. Ravna gora, Šu- teljstvo, Zagreb, 1999. marski list 11-12 /58, Zagreb 1958 Osnova gospodarenja "Bjelovarska bilogora"; važi od Ugrenović,A. 1957: Eksploatacija šuma; Udžbeni- 01.01. 1993.-31. 12. 2002.; Uprava šuma Bjeci Sveučilišta u Zagrebu, Zagreb, str. 1 -481. lovar, 1993. Va siljević,J. 1972: Osržavanje bukve na području Šumarska enciklopedija I str. 83-85, 438, II str. 33-39. Zrinske gore, Sveučilište u Zagrebu, Šumarski SUMMARY: The subject of research were the frequency and scope of the occurrence of false heartwood in beech roundwood coming from thinning and preparatory felling in the economic unit Bjelovar Bilogora. Research was carried out on 15 jelling sites and 835 exemplary trees, 573 of the trees coming from 11 instances of thinning felling, aged between 50 and 91 years, and 262 exemplary trees from 4 instances of preparatory felling, aged between 100 and 110 years. Appearance of false heartwood in trees was researched with regard to the type of felling and age of trees, number of trees with false heartwood, according to diameter class for thinning and preparatory felling, as well as the percentage of false heartwood volume in the volume of technical roundwood with false heartwood in thinning and preparatory jelling. False heartwood of beech trees was not found in thinning felling up to 50 years of age. In thinning felling of trees of approximately 60 years of age, false heartwood appears in less than 4 % of the trees, while in thinning felling of trees aged between 70 and 90 years, it occurred in about 15 % of the trees. In preparatory felling (main yield), aged between 100 and 110 years, the percentage of trees with false heartwood is considerably higher, and its value stands at about 50 %. A smaller number of trees with false heartwood, according to the diameter class, were found in previous yield jelling, aged between 50 and 91 years, than in preparatory felling, aged between 100 and 110 years. Percentage of false heartwood in the volume of technical roundwood with false heartwood amounts to 1,5 %for the thinning jelling aged up to 60 years, while for the thinning felling aged between 70 and 90 years, the percentage ranges between 4,9 % and 17,9%. In preparatory jelling, percentage of false heartwood in the technical roundwood is fairly unchangeable, and it varies between 6 % and 8,8 %, or 7,6% on average. Percentage values of false heartwood in the volume of technical roundwood decrease whit the increase of diameter class, i. e. with the breast diameter of the tree. In planning the assortment structure of previous yield, occurrence of false heartwood does not have major significance, since we can expect up to 15 % of trees with false heartwood in older thinning felling. On the other hand, while planning assortment structure of preparatory felling, i. e. main yield, the frequency of the occurrence of false heartwood has a great significance, since we can expect it in approximately 50 %> of marked trees. Key wo rds: false beech heartwood, beech felling, assortment structure |