Improvement of Quality Grading of Douglas Fir Logs


1Department of Wood Industry, Faculty of Forestry Sciences, Agricultural University, Tirana, Albania

2Department of Forestry, Faculty of Forestry Sciences, Agricultural University, Tirana, Albania


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Positioning of Douglas fir’s branches (Pseudotsuga menziessi Mirbel.) at the same level in the form of branch whorl is a morphological characteristic of this wood. Actually the standard EN 1927-3 does not take into consideration this morphological feature for quality grading of logs. A study was carried out to estimate the influence of this morphological feature on the qualitative grading of Douglas fir logs. The method was based on the system “free of branch sector” of transversal section where the branches are positioned. There were applied five quality classes referred to the “free sector”. There were sawed 48 logs sampled from 40 to 45 years old forests located in the regions of Stravaj (Librazhd) and Biza (Tirana). The logs diameter varied from 40 to 60 cm. Interknots along the log were from 40 to 55 cm far from each other, without any difference between the two regions. In small diameter logs the “free sector” did never exceed 2/3 of the transversal section, while in large diameter logs it could take the 4/5 of the section. In regard with the whole sample the “free sector” was decreasing with increasing the height of the tree. After sawing, there was observed a positive relationship between the “free sector” and the sawn timber quality yield. This was clearly evidenced to logs with diameter over 50 cm. According to these results the “free sector” appears as a pin-pointing remark for quality classification of Douglas fir logs with a diameter over 50 cm.

Keywords: quality, Douglas fir, branch whorl, free sector, sawing..

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