Though seldom seen by visitors, periodic, large-scale fires burn across Denali National Park and Preserve. The National Park Service manages ninety-three percent of the park as a Limited Management Option. This category recognizes areas where the cost of suppression may exceed the value of the resources to be protected and the exclusion of fire may be detrimental to the fire dependent ecosystem. The primary management strategies protect human life and specific resources and allow fire to contribute its natural role in the ecosystem.
The natural role of wildland fire at Denali varies considerably across the park and preserve's geographical zones. Much of Denali consists of higher elevations, including many glaciers and exposed rock in the Alaska Mountain Range; areas which lack substantial fuels and are not necessarily prone to fire. Fuel means combustible material such as grass, leaves, plants, shrubs and trees that feed a fire. South of the range, the receptivity of fuels to fire lessens due to higher levels of precipitation and humidity. The range blocks this wet moisture from traveling north, thus less precipitation falls on the boreal forest north of the range. North of the Alaska Range, fire has been and continues to be a constant force of change.
Periodic fires of considerable size and intensity prevail north of the range, as evidenced by forest mosaic patterns and local history. Throughout time, fires have served to select plants and animals that adapted to fire-caused change. Both black and white spruce depend on intense ground fire to clear organic layers thereby exposing fertile seedbeds. Moreover, black spruce partially depends upon fire, in that its seeds ready for germination at the peak of the Alaskan interior fire season and are released when its semi-serotinous cones open by canopy fire. Furthermore, fire plays a key role in the regulation of the permafrost table. Without the routine occurrence of fire, organic matter accumulates, the permafrost table rises, and ecosystem productivity declines. Vegetation communities, wildlife habitat and wildlife become less diverse. Fire, the agent of change, removes some of the insulating organic matter, elicits a warming of the soil, maintains and rejuvenates these systems.
Did You Know?
The vast landscapes of interior Alaska are changing. Large glaciers are receding, permafrost is melting and woody plants are spreading. Comparison of "then-and-now" photographs and data from major vegetation monitoring should allow detection, understanding and potential management of these changes.