Entomology > Spruce Budworm

Summary of a project funded under British Columbia’s Forestry Innovation Investment Program

Spruce Budworm and Sustainable Management of the Boreal Forest

Current trends in sustainable forest management take the view that natural disturbances, such as fire and insects, are necessary for the maintenance of the forest's ecological balance. In theory, forest management strategies that imitate the effects of natural disturbances will preserve forest resources and maintain forest health.

Economic Importance

Damage caused by the spruce budworm is of concern to forest managers because of the potential losses it may inflict to important timber and non-timber resources of the boreal forest. The spruce budworm caterpillars consume part or all of the new foliage of spruce, balsam and other conifer trees. Severely defoliated trees grow more slowly, reducing wood production. Some trees will die from repeated budworm damage and poor health. Some trees that survive the budworm outbreak will often have a crook in the stem where a branch grew up to replace a killed tree top, reducing the timber value of the tree. Changes in tree species composition, tree age class distribution, tree density and understorey characteristics affect the supply of habitat of plant and animal species that live in this vast forest.

Project Objectives

• Determining the historical frequency of budworm disturbance in the Ft. Nelson Forest District of British Columbia
   
• Developing methods to measure its extent and intensity with satellite images
   
• Determining what makes the forest susceptible to defoliation
   
• Measuring the impact of defoliation on forest health and resources.

Distribution of the spruce budworm (C. fumiferana) and other
budworms in Canada

Fort Nelson Forest District with impact plot locations and the 2001 (close to the maximum recorded in the area) extent of spruce budworm defoliation.