Unit 5 -  Forest Protection

Lesson 2: Forest Fire as a Natural Disturbance

Historically, forest fires were seen as something to be prevented. Early forest management practices encouraged total fire suppression.

Today, however, we realize fire is a natural disturbance in forest ecosystems and forest fires actually play a critical role in ensuring the health and diversity of the forest, as described below:

  • Fires reduce the number of pests and the occurrence of disease in the forest.

  • Fires reduce the amount of litter on the forest floor. Litter is dead/decaying leaves, logs, and needles. Unless this litter is periodically cleaned up by forest fires, it accumulates. The end result is an excess of fuel on the forest floor that can result in a fire.

Reestablishment after a forest fire in Banff National Park, Alberta

  • Fire increases species diversity within the forest.

    • Some species are very resistant to fires, while others are not. Some tree species such as jack pine, lodgepole pine and aspen depend on fire for regeneration.

    • Fire creates openings in the treetops, allowing sunlight to reach the forest floor. This allows sun-loving species to establish. Once these species are large enough, they will begin shading the forest floor themselves (causing shade-loving species to dominate once more).

    • Fire releases nutrients back into the soil. Following a fire, nutrients are more abundant and accessible to vegetation. This favours new growth, which attracts grazers such as deer and moose.

    • The number of insects increases following a fire. For example, burned timber attracts beetles which provide a food source for birds. Increased numbers of insects also attract a variety of other species.