U radu je istraživana vjerojatnost pojave drvnih sortimenata tehničke oblovine u bukovim stablima s obzirom na vrstu sijeka, kao i razlike između postotnih udjela drvnih sortimenata tehničke oblovine po debljinskim stupnjevima i vrsti sijeka. Postotni udjeli tehničke oblovine određeni ovim istraživanjem uspoređeni su s planskim vrijednostima (sortimentnim tablicama) koje se primjenjuju u šumarskoj operativi. Na temelju rezultata istraživanja izrađene su nove sortimentne tablice prema Hrvatskim normama proizvoda iskorištavanja šuma od 1995. godine. Istraživanja su provedena na uzorku koji obuhvaća 787 stabala u proredama, 1025 stabala u pripremnim, 606 stabala u naplodnim i 583 stabala u dovršnim sjekovima. Sveukupno je istraživanjima obuhvaćeno 3001 primjerno stablo. Starost istraživanih sječina iznosila je od 59 do 91 godinu kod prethodnog prihoda (proreda), od 94 do 110 godina kod pripremnog sijeka, od 100 do 112 godina kod naplodnog sijeka te od 98 do 112 godina kod dovršnog sijeka.
Dosadašnji je pristup određivanju sortimentne strukture jednodobnih bukovih sastojina u velikoj mjeri pogrešan. Operativne sortimentne tablice daju previsoke procjene za najkvalitetnije drvne sortimente svih vrsta sjekova osim zadnjih sjekova oplodnih bukovih sječina. Tablice šumskih drvnih sortimenata koje uvažavaju vrstu sijeka kao jedan od ulaza, omogućuju pouzdaniju procjenu sortimentne strukture sječine i preciznije planiranje sječivog etata. Pri tome su kao čimbenici razdvajanja uzeti kriteriji selekcije prilikom doznake stabala za sječu koji se primjenjuju do uključivo pripremnog sijeka. Iz tih su razloga tablice šumskih drvnih sortimenata izrađene zasebno za prorede i pripremni sijek, a zasebno za naplodni i dovršni sijek.The subject of research was probability of appearance of technical roundwood timber assortments in trees according to type of felling, as well as the difference between shares of technical roundwood timber assortments according to diameter class and type of felling. The percentages of technical roundwood established in this research were compared to the planned values (assortment tables) which are applied in forestry operational bodies. Research was carried out on a sample consisting of 787 trees in thinning felling, 1025 trees in preparatory felling, 606 trees in seeding felling and 583 trees in final felling. An overall number of 3001 exemplary trees were included in the research. The age of the felling areas studied was between 59 and 91 years in the preliminary yield (thinning), 94 to 110 years in preparatory felling, 100 to 112 years in seeding felling, and 98 to 112 years in final felling areas.
We think that the approach to establishing the assortment structure of even-aged beech stands taken so far is to a large extent wrong. The operative assortment tables give too high estimates of top quality timber assortments of all types of felling, except the final felling of seeding beech felling areas. Timber assortment tables that take into consideration the type of felling as one of the inputs, enable a more reliable estimate of assortment structure of the felling area and more precise planning of timber mass marked for felling. In this case, as a distinguishing factor, we took the selection criterion for marking trees for felling which is applied for the types up to, and including, the preparatory felling. For that reason, timber assortment tables were made separately for thinning and preparatory felling, and separately for seeding and final felling.
On the basis of the research results, new assortment tables were made according to Croatian Standards of Forest Exploitation Products from 1995. Seeding and final felling show by ca 8–14 % higher shares of top quality timber assortment (F and L) than thinning and preparatory felling. On the other side, thinning and preparatory felling show by ca 4–15 % higher shares of technical roundwood assortment of lower quality (second-class and third-class) than seeding and final felling
