Light and fog on Mount Brown a year after the 2017 Sprague Fire burned through the area. Fireweed is one of the first spots of color to return.
Fire is a powerful force of nature. It’s a disturbance that resets the ecological clock—consuming old and dead material in the forest and making way for new regrowth.
While it’s easy to see a landscape as a snapshot in time—the way it appears on a postcard, or the way you first encountered it—forests and ecosystems are always changing. Disturbances like fires, as well as landslides, avalanches, and insect outbreaks, occur rapidly and are very noticeable. But other changes are happening all the time: erosion of cliffs and hillsides; the arrival of non-native species; the steady growth of mature forests.
A burned forest may look stark and dead, but fire is a natural process that helps maintain a healthy forest. In many ecosystems, including Glacier, fire is an essential element of the landscape. While the loss of homes, property, or human life is a tragedy to be avoided, fire is a beneficial force necessary to ensure forest succession.
Fire Effects
Fire is a major ingredient in the ecology of the Northern Rockies just like snow, wind, rain, and other natural forces. Wildland fire is an essential component of this ecosystem and native plants and animals are well adapted to it. While fire benefits some more than others, any species living in the forests of Glacier has to live with fire.
Animals
Most animals, plants and trees in the park have evolved with fire. Some plants thrive in soil with a thick layer of ash, and other plants benefit when a fire opens up the canopy of a forest, allowing more sunlight to reach the forest floor. These nutritious young plants provide forage for many animals, and as these populations flourish, so do predators and scavengers. Cavity-nesting birds take advantage of dead snags, and many birds thrive on the increase in insects found in decaying trees after a fire.
While it happens occasionally, it’s rare for wildlife to get caught in a fire. Larger animals can usually move out of the way, and most small animals, amphibians, and reptiles avoid fire by seeking refuge in tunnels underground, under downed logs, or in damp areas.
Plants resprouting after the 2017 Sprague Fire.
NPS Photo
Plants
Downed logs and duff on the forest floor are burned to ash, releasing nutrients back into the soil. Where dense tree canopies previously shaded the forest floor, wildflowers thrive in the nutrient-rich post-fire soil, creating a high-contrast landscape of blackened bark, colorful flowers, and green plants. Shrubs like serviceberry and huckleberry resprout after a fire, producing a more vigorous plant with increased fruit production. Many plants have roots or bulbs that can survive a fire below ground are able to produce new growth immediately, even if the above-ground parts of the plants are burned.
Some plants are highly fire-adapted, like lodgepole pines. While they produce normal cones with seeds inside, they also have what are called serotinous cones, which are held tightly closed by a sticky resin. When the cones are exposed to the heat of a fire, the resin melts and the seeds inside are released. So while large stands of lodgepole pine may burn, the seeds carpet the forest floor and produce a massive regeneration of seedling after the fire. An individual tree may not survive, but the species will reproduce and thrive.
Other trees are adapted to survive fire. Older ponderosa pine trees, western larches, and Douglas fir trees have thick bark that insulates the inner living tissue from the heat of a fire.
A mosaic of burned and unburned trees near Sperry Chalet after the 2017 Sprague Fire.
NPS Photo
Forest Mosaic
Looking at a map, a fire perimeter is a line on the landscape—burned inside the line, unburned outside. But it’s not that simple. Some areas inside the fire footprint may be completely unburned; other sections may have burned at low- to moderate-severity; and some areas may be completely blackened by high-intensity fire. The result is a dynamic blend of habitats called a forest mosaic.
The diverse stands of forest seen throughout the park are in different stages of regeneration. Some have seen fire repeatedly, while some old growth stands in wet areas have escaped it. Glacier National Park has been described as one of the most intact natural ecosystems in the lower 48 states, and fire has played a dominant role in creating its rich biological diversity.
Learn more about the effects of fire by exploring the Forest and Fire Nature Trail app tour. Download the National Park Service app, select Glacier, and look for Self-Guided Tours.
Looking Ahead
Climate change is already having an impact on the nature of wildland fires. Observed changes in Glacier’s climate include higher temperatures and altered precipitation patterns. This area is also seeing less snowfall, earlier snowmelt, and an increasing number of hot days. These factors are combining to increase the frequency and size of wildfires, and to extend the length of wildfire season.
Between 1984 and 2015, about 22 million acres of forest burned in the Western United States. Fire and climate modelling conducted by scientists at the University of Idaho and Columbia University estimated that about half of that acreage—11 million acres—were attributable to human-caused changes in our climate (Abatzoglou and Williams, 2016).
The Meet the Fire Scientist series profiles fire scientists, including fire ecologists, vegetation ecologists, fire effects monitors, and fire archeologists.
