Fire hazard in budworm-killed balsam fir stands on Cape Breton Highlands

Abstract

The forests subject to budworm attack in eastern Canada vary considerably in tree species composition, and the severity of fire weather in those regions also varies. It is likely, therefore, that fire hazard or fire potential in budworm-damaged forest has complex causes. A forest of mixed conifers near the Aubinadong River in central Ontario represents probably one extreme situation, that of an abundance of combustible surface and aerial fuels coupled with high fire weather severity. This has resulted in many fires that are difficult to control. Then there are the pure and mature balsam fir stands of the Cape Breton Highlands in Nova Scotia, which have no apparent fire history and represent the other extreme: no accumulation of combustible surface fuels and low fire weather severity. A systematic study was undertaken between 1979 and 1988 in the Highlands, following a major budworm epidemic in the 1970's, to measure fire hazard quantitatively by monitoring changes in fuel distribution, and to evaluate fire weather severity and its seasonality. The results indicate that the cool and moist climate of the Highlands decomposed dead fuels rapidly, and there was little accumulation of surface combustibles. Furthermore, fire weather severity is low, and even when an unexpected drought occurs, direct attack and attainment of control of wildfire in these stands can be achieved with existing resources.