Predicting the value of grey alder (Alnus incana) logs based on external quality

Abstract

The quality of grey alder logs (Alnus incana) was studied by sawing sample logs from two different forests in November 1995-February 1996. For grading of grey alder logs and sawn timber the proposed system of Keinanen and Tahvanainen (1995) plus the reject-grade was used. In general, grey alder logs have knots from the base to the top. All types of knots appear, and the length of the knot-free section is small at the base. In small-dimensioned logs there are fewer knots than in larger logs. Especially in large top logs, there were many more fresh knots than in other types of logs. Evidently, in different types of logs the different grades of sawn timber are located in comparable sections along the length. It also seems that the worse the grade class was, the longer was also the length of the class. The most common reasons for decreasing grade were dry knots and discoloration.