Insect Attack and Value Loss in Wind-damaged Spruce and Jack Pine Stands in Northern Ontario
The forests of northern Ontario are damaged frequently by strong winds that develop along cold fronts. Deterioration of spruce (Picea spp.) and jack pine (Pinusbanksiana Lamb.) saw timber because of wood-boring insects was studied in an extensive area of blowdown between 1969 and 1972. Sawyer beetles (Monochamus spp.) were the most important agents of degrade, but a surprising amount of damage was caused in spruce by Tetropium spp. Broken trees fared worst, but all uprooted trees were heavily attacked by 2 years after the storm. Milling studies showed about a 10% loss in all material combined 1 year after the storm, with the loss in general more than doubling in the 2nd year. The greatest loss occurred in white spruce (Piceaglauca (Moench) Voss), which was of greater original value than jack pine. Trees left standing were not attacked by emerging beetles but were subject to windthrow by relatively light winds. Salvage operations, when desirable, should begin as soon as possible after a blowdown and all stems, including those left standing, should be harvested at once.