Prediction of knot diameter in Picea abies (L.) Karst

(L.) Karst. from three different site indexes in south-eastern Norway. Ten branch whorls were sampled from each tree, and diameters of all the knots were measured at the radial stem plane. Knot diameter was evaluated as mean diameter of the two thickest knots in each sample whorl. The whorl with the maximum value in each tree was on average located at 30% of tree height at G11, 40% at G17 and 60% at G23. The vertical location was related to the position of the crown base, and single tree models for predicting the position and the value were constructed. Knot diameter in the butt log, i.e. in the lower 30% of tree height, was related to annual ring width and site index, and to diameter at breast height and site index.