Prolonged storage of birch timber in the forest results in remarkable raw material losses for veneer and plywood industries. Prolongation is typical for small timber lots, such as Finnish veneer birch lots (on average 5-15 Kubikmeter). The Finnish Forest Research Institute studied the insect damage, stain, decay and decrease in basic density of birch timber caused by one-summer and two-summer storage in the forest and their relationships with stem and bolt properties. In addition, losses in the yield, grade and value of rotary-cut veneer were studied. Storage trials were performed by 453 two- meter long bolts which were made of 30 tree pairs, each consisting of a silver birch and pubescent birch (Betula pendula and Betula Pubescens). Of these, 226 one-meter bolts with a diameter of 14 cm or more were cut for rotary-cutting. During the first summer of storage, Scolytus ratzeburgi caused inconsiderable stain in sapwood underneath bark, other stain and decay were constrained in the vicinity of bolt ends, basic density slightly decreased there and the overall deterioration was mild. After the second summer, considerable damage by Trypodendron signatum were observed, and stain and decay extended on average to 45cm distance from the bolt end. Stain and decay were the actual causes for the decrease of veneer yield by 12%, essential deterioration of veneer grade for appearance, and decrease in veneer value by 46%. Total value of veneer, chips and bark decreased by 41%, i.e. 453 FIM per one Kubikmeter birch timber. The decrease in value is reduced by increasing timber length. In storing veneer birch logs, cut to the conventional length of 3.1 to l.7m, the estimated decrease was 12-27%, i.e. 135-292 FIM/Kubikmeter.
34 (Lagerung des Holzes im Wald und auf Poltern (Sammelplätzen) [Auf Fabrikhöfen und Holzplätzen siehe 848]) 832.281 (Furniere) 832.282 (Sperrholz) 845.2 (Auf dem Land lebende Holzbohrer außer Termiten) 176.1 (Dicotyledoneae [Siehe Anhang D]) [480] (Finnland)
