FBP Fuel Type Descriptions
M3 - Dead Balsam Fir Mixedwood–Leafless
This fuel type (and its "green" counterpart, M4) is characterized by mixedwood stands in which balsam fir (Abies balsamea (L.) Mill.) grows, often as an understory species, in a heterogeneous mix with spruce (Picea spp.), pine (Pinus spp.), and birch (Betula spp.). These stands are found in the Great Lakes – St. Lawrence and Boreal Forest regions of Canada and are not to be confused with the pure balsam fir stands typical of Nova Scotia and New Brunswick. Repeated annual defoliation (due to spruce budworm (Choristoneura fumiferana Clemens) attack) causes balsam fir mortality, followed by peeling bark, draped lichen (Spanish moss or old man's beard, Usnea spp.) development, top breakage, and windthrow, peaking 5–8 years after mortality. The volume of down woody material is initially low but increases substantially with progressive stand decomposition following mortality. The forest floor is a mixture of feather mosses, conifer needles, and hardwood leaves. The organic layer is moderately compacted and 8–10 cm deep. After mortality, spring fires in this fuel type behave extremely vigorously, with continuous crowning and downwind spotting.
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