DIGITALNA ARHIVA ŠUMARSKOG LISTA
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ŠUMARSKI LIST 1-2/2009 str. 38 <-- 38 --> PDF |
Ž. Zečić, I. Stankić, D. Vusić, A. Bosner, D. Jakšić: ISKORIŠTENJE OBUJMAI VRIJEDNOST DRVNIH ...Šumarski list br. 1–2, CXXXIII (2009), 27-37 According to the assessment of forest condition in Croatia (ICP FORESTS) for the year 1999, undamaged fir trees accounted for only 14.3 %, whereas severely damaged trees accounted for as much as 63.8 %. Severe damage denotes crown needle loss ranging from 26 % to 99 % (Potočić and Seletković 2000). Particularly high participation of damaged fir trees of 81.6 % was recorded in Gorski Kotar in 1999, while only 3.8 % were healthy fir trees. The results of field research suggest that the portion of damaged fir trees is constantly increasing. Thus, as much as 88.4 % of severely damaged trees were recorded in 2004 (Vrbek et al. 2008). The value of wood assortments of dead trees from salvage cuts is lower compared to those obtained from regular silvicultural treatments in healthy selection stands. The goal of this research is to analyze the quantity, quality and value of wood volume obtained from salvage cuts of silver fir in a selection forest. The research was conducted in the area of Gomirje forest administration within the management unit of “Potočine – Crna Kosa”. The management unit extends over northern and north-eastern slopes of Mt. Velika Kapela at altitudes between 339 and 1,200 m. The compartment covers an area of 36.00 ha. The management class is a managed forest of silver fir and common beech with a total growing stock of 339 m3/ha. The growing stock of fir is 112 m3/ha. There are 304 trees per hectare, of which 157 are silver firs. To investigate fir trees during salvage cuts, breast diameters and heights were measured on every blazed tree and crown damage was directly assessed using the ICP FORESTS methodology. Trees marked for cutting were divided into two classes (degrees) of crown damage (“3b” and “4”). Crown damage for class “3b” ranges between 81 % and 99 %, while class “4” represents completely dry trees (Figure 3). The volume of each marked tree was calculated according to the Schumacher-Hall expression. Values of wood and timber assortments change in accordance with changes in the society, on the market and in economic relations, and in accordance with the application of new technologies and impacts of other factors (Rebula 1996). Value analysis of the obtained wood volume is made by determining the price of every single timber assortment. The price of every single piece of roundwood corresponds to the valid pricelist of the main forest products. The pricelist is used to calculate the price of roundwood from forests owned by the Republic of Croatia during the sale of standing trees (“on the stump”) to contractual buyers. Value coefficients were established in accordance with mutual relations of price classes in relation to the most represented price class, which was taken as 1.00. The results were expressed by the relative value ratio of timber assortments produced from trees in crown damage classes “3b” and “4”. Figure 3 shows distribution of dead silver fir trees in compartment 7b with regard to crown damage degree. Diameter classes range from 17.5 cm to 77.5 cm. The lowest number of trees, i.e. only one tree, was in the largest diameter class, while the majority of the trees were in the diameter class of 47.5 cm. A total of 200 trees with average breast diameter of 48 cm and average height of 29.4 m were marked and processed. A comparison of the total marked volume determined with the Schumacher-Hall form and the volume taken from the mentioned tables is given in Figure 5. The comparison wasmade on the basis of individual and total tree volume. According to Šurić, the total volume of marked trees was 491.93 m3, according to Schuberg it was 570.32 m3, and according to Schumaher-Hall it was 570.95 m3. Statisticallysignificant differences (for p<0.05) were found in Šurić – Schuberg and Šurić – Schumacher – Hall relations, whereas insignificant difference was found in the comparison of volume of Schuberg – Schumacher–Hall. |