Fire destroys and renews. The boreal forest of the Sahtu has been shaped by fire for thousands of years. All life in these forests has in some way adapted to or, in many cases, come to rely on the presence of natural wildfire. In the heart of boreal, natural fire frequency probably ranges from 50 to 200 years. Some areas burn more frequently, some less. Below is a map showing the forest fire history of the Sahtu.
What does fire do for the forest?
- breaks rock and builds soil
- kills pathogens and bacteria
- clears accumulated leaf (needle) litter exposing good mineral-soil seed bed
- fire blackened soil absorbs light, creating greenhouse effect for seeds and seedlings
- knocks back fire-sensitive/shade-tolerant trees
- helps re-establishment of conifer forest
- recycles nutrients locked up in leaf litter and woody debris.
Black spruce and Jack pine are well adapted to fire. Black Spruce cones tend to sit high on the tree to ensure the best chance of seed survival during a fire. Their semi-waxen seal often breaks open after a fire, allowing reseeding of the burned area.
Jack pine are thin barked and highly resinous. Biologists have described these trees as "roman candles" that can literally explode into flame. Jack pine cones only open under high heat – 50 degrees Celsuis or more – and its seedlings need the open post-fire conditions to thrive.
Natural fires can range drastically in intensity, from smouldering ground fires that slowly clear off leaf litter to searing crown fires that destroy all vegetation in their path. Interestingly, it is now widely acknowledged that our efforts to suppress wild fires may in fact be skewing the pattern of wildfires toward less frequent, but much larger, hotter fires. By allowing dead wood and other fuels to build up in the forest, we are actually setting the stage for more destructive fires.
Forest Fire History In The Sahtu
top - Tulita fire 1995
middle - water bomber demonstration
above - fire crewpreson puts out hot spot