• CANUSA
  

Effects of Spruce Budworm Caused Defoliation On The Growth Of Balsam Fir

Forest managers must be able to predict accurately wood production of different stand types in order to allocate harvesting for a sustained yield. When it is fore- cast that the forest resource will be in short supply, as it will be for some provinces in eastern Canada, the precision of wood supply predictions becomes very important. The manager must have reliable information about growth rates of forests and the effects on growth of external influences such as budworm defoliation. How- ever, few data presently exist to quantify the loss of wood production. Past studies of the effects of defoliation on the growth of host trees have generally lacked detail and often considered only growth loss at breast height. Attempts to relate this to some gross measure of defoliator (e.g., a light-moderate-severe scale) have not been very successful, and the need for more comprehensive studies of defoliation and growth loss has been recognized by both forest managers and researchers for several years.