The interior knot structure of Pinus sylvestris stems

Knots negatively influence the use of pine wood for many products. Knowledge on the interior knot structure of the stems is therefore essential for many decisions regarding wood utilization. This knot structure was studied using data from 185 stems of Scots pine (Pinus sylvestris L.) scanned by computerized tomography. First with respect to distance between whorls and number of knots per whorl, and second, by dividing the stems into knot structure sections, to determine if knot diameters follow some kind of predictable and uniform pattern. The results showed that distance between whorls and number of knots per whorl both increased with increasing site index and reached their maximum values at 2-4 m height in the stems. The study also showed that a division of the stems into four knot-structure sections can be a useful basis for description of the interior knot structure. These sections were named establishment section, constant growth section, retardation section, and crown section.