Wildfires are a natural process in Alaska that has shaped boreal forests for thousands of years. With the high frequency of forest fires caused by lightning, it is natural to consider that plants and animals have adapted to fire as a natural part of their existence.
Fires burn at different intensities, influenced by the type of vegetation, terrain, weather conditions and many other factors. As fire moves across a landscape, it leaves areas unburned, lightly burned, or heavily burned (severe fire, deeper in the organic soil layer). This mosaic burning pattern creates a variety of habitats for wildlife. Heavily burned areas usually seed and repopulate over a period of years, while lightly burned areas regrow fairly quickly under the right conditions. Alaska’s signature flower, the fireweed, gets its name from the fact that it can revegetate quickly after wildfires. This is due to deep roots that are well insulated below the ground from the heat of the fires.
Black spruce is an example of a tree species that has adapted to fire or long periods of hot weather. The cones are sealed with resin and only open in the heat of a fire or years of hot summers in the sun. When the cones open and the seeds scatter on the ground, many of them will sprout into new trees. Another example is trembling aspen, a minor but widespread forest type in interior Alaska. The fire that kills standing trees allows the clone’s connected root system to sprout young stems, often in the same year as the fire. There are many other examples in fire-adapted ecosystems in Alaska.
Unfortunately, some animals perish in the fire because of the smoke and flames. However, many animals survive by moving into unburned areas or burrowing underground until the fire passes. Habitat changes caused by fire affect wildlife differently. An intense fire that has removed trees, shrubs and other vegetation forces some of the wildlife to move to different areas for food and cover, while other wildlife is drawn into a newly burned area a once new plants begin to appear.
Examples of wildlife attracted to burned areas include bark beetles which feed on the inner bark of trees that have been killed or injured in a fire. As the beetle population increases, they attract woodpeckers that feed on them. New grasses, shrubs and trees growing or seeding in newly burned areas provide a rich food source for insects, birds and small mammals. Predators are then attracted to the areas due to the abundance of prey and their ability to more easily find voles and other small mammals. Bears and other large mammals soon find themselves in the burned areas along with the new growth of grasses and shrubs bearing edible berries.
The boundaries between burned and unburned areas also provide opportunities for a variety of wildlife. Edges are easier to navigate and find food in burnt and unburnt areas. Many animals thrive on the diversity of more than one habitat during the changing seasons. According to an article titled “Regeneration After Fire Creates Fertile Wildlife Habitat” from the Alaska Department of Fish and Game, lynx, marten, moose, black and brown bear (grizzly ), snowshoe hare and resident birds like hoopoe and spruce grouse forage on early successional plants after a fire and seek shelter in nearby unburned forest.
As trees and shrubs become established in burned areas years later, they provide habitat for many breeding birds as well as moose, which feed on willow bark and leafy trees in winter. As this new forest ages and the hardwoods are replaced by spruce, porcupines, red squirrels and caribou move into boreal spruce habitat.
For thousands of years, wildlife has lived in tandem with fire, causing a natural and essential adaptation. As long as there is lightning, Alaska will continue to experience wildfires. Weather and receptive vegetation help spread the fire, which continues to play a vital role in the rich animal and plant life found in Alaska’s boreal forest region.
The link to the attached flyer illustrates logging practices that mimic natural disturbances like fire and river action (flooding, ice scour). It contains the fire succession diagram that illustrates post-fire succession: http://www.adfg.alaska.gov/static/lands/habitatrestoration/pdfs/managing_alaska_boreal_forest_wildlife_flyer.pdf
~ Story by Public Information Officer Pat York, Alaska Fire Information Center, (907)356-5511, [email protected]
Categories: AK Fire Info