Master of Arts (MA)
Geography & Environmental Studies
Faculty of Arts
The spruce budworm Choristoneura fumiferana Clem. is the foremost forest pest in Canada. The species is endemic to eastern North America. Since the turn of the century the insect has become a major problem in the “Great Lakes St. Lawrence Forest Region” of Ontario, an area where prior to recent times the insect did not occur in damaging numbers.
Analysis of the life cycle of the insect reveals that the only limiting factor capable of controlling outbreaks is a lack of food. The required tree species is balsam fir Abies balsama (L.) Mill. The forests of Ontario have been altered to favour the balsam fir. Logging of the former pine forests that once dominated the landscape and the fires which followed are responsible for such change. It has also been shown that changes in the climate may also be responsible for the increase in balsam fir as a dominant species of the forests of Ontario.
Once established balsam fir forests and the spruce budworm are a self-regulating natural system, an evolved process that ensures a future food supply for the insect. The suppression of forest fires since the logging era is also shown to encourage the continual presence of high balsam fir content forests. The budworm will continue to thrive and cause damage in that region where it did not formerly occur in significant numbers.
Bowen, John F., "Changes in the Forest Composition in the Great Lakes St. Lawrence Forest Region of Ontario and the Resultant Outbreaks of the Spruce Budworm Choristoneura fumiferana (CLEM.)" (1979). Theses and Dissertations (Comprehensive). 1485.