Fire Ecology

A forested area 5 years after a fire

NPS/Stephanie Metzler

Fire is a powerful force of nature. While burned trees may look stark and dead, they are evidence of a natural process that helps maintain a healthy forest. In many ecosystems fire is essential for the continued survival of both the plants and animals that live there. While loss of homes, property or human life is a tragedy to be avoided, fire is a beneficial force necessary to ensure forest succession.

 

Already back in the forest after a fire

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Fire Effects

Fire is a major ingredient in the ecology of the Northern Rockies just like the snow, the wind, the rain, and other natural forces. Wildland fire is an essential component of this ecosystem and native plants and animals are well adapted to it.

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. Various animals forage on these young plants. It is rare for mammals to get caught in a fire. Larger animals are able to move out of the way and most small animals, amphibians, and reptiles avoid fire by seeking refuge, often in tunnels in the ground, under large downed logs, or in damp areas. Grazers (such as elk, rodents, and ground squirrels) and browsers (such as deer and moose) find new habitat and succulent vegetation where only unpalatable plants grew previously. As these populations flourish, so do predators and scavengers. Birds that nest in cavities take advantage of dead snags and other birds thrive on the increase in insects found in decaying trees.

 

A willow returns remarkably quickly

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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 ground, fireweed, lupine, pinegrass, spirea and willows will thrive in the newly nutrient-rich soil, creating a high-contrast landscape of blackened bark, bright flowers, and green plants. Shrubs such as serviceberry and huckleberry resprout after a fire producing a more vigorous plant, which increases fruit production. Many shrubs and plants have roots or bulbs that are able to produce new growth even if the above-ground parts of the plants are burned.

Some plants that live in fire-prone areas have adaptations that need fire to ensure the survival of the species in that area. Lodgepole pines, for instance, 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 large numbers of stored seeds are released. When fires occur, large stands of lodgepole pines may burn, but the seeds produce a massive regeneration or seedling trees after the fire. An individual tree will not survive a fire, but the species will reproduce and thrive.

Other trees are adapted to survive fire. Older ponderosa pine, western larch, and Douglas fir trees have thick bark that insulates the inner living tissue from the heat of a fire. Larch trees have additional fire adaptations. In an intense fire they can lose all their needles to the heat, and then can grow new ones and even replace burned branches along the bole of the tree. These survivors provide seed for reforestation.

 

A mosaic near Apgar Mountain, 2003

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Forest Mosaic
Seldom does everything burn within a fire perimeter. Some areas may be untouched by flames, while adjacent sections burn at a low to moderate severity. These areas will rejuvenate quickly. Other areas are fully engulfed, but will in time provide a vibrant habitat. The result is a dynamic blend of mixed severity burned and unburned forest called the forest mosaic.

The diverse stands of forest seen throughout the park are in different stages of regeneration and everyday move one step closer to a time when they will once again be blackened. Glacier National Park has been described as one of the most intact natural ecosystems in the lower 48 states. Fire has played a dominant role in creating the rich biological diversity.

 

Looking Ahead

Climate change patterns have an impact on the nature of wildland fires. Observed climate changes in the Glacier area include increased annual and minimum/maximum temperatures and altered precipitation patterns. Less snowfall, earlier snowmelt, and the increasing number of hot days and length of season in which they occur combine to create conditions suitable for increased frequency, size, and duration of wildfires.

Already we have seen that the forested area burned in the western US from 1987 to 2003 was more than six and a half times the area burned from 1970 to 1986. More frequent large wildfires and longer wildfire seasons will certainly have an effect on park lands, air quality, and visitor experiences.

For more info about fire and climate change:
Crown of the Continent Research Learning Center fact sheets
US Forest Service Climate Change Resource Center website

 

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Be sure to read the many Crown of the Continent Research Learning Center's resource briefs on Fire Ecology.

See the Fire Education page for even more sources.