Fire Effects

Fire is an important agent of change in many of Denali’s ecosystems. It is a naturally-occurring disturbance to many plant communities. Fire breathes new life and vigor into aging ecosystems and processes. Through observation, one can identify many ways in which fire benefits ecosystems.

As fire burns, it can release seeds of fire-adapted species such as Black Spruce (Picea mariana). Many plants resprout from their burned stems. Downed and dead woody material turns to ash to feed the next crop of growth. Fire burning through tundra consumes organic matter like dead leaves and grasses. Fire deposits valuable nutrients that feed recovering plant communities.

Many forest and tundra systems are fire-adapted. But changes to patterns in fire frequency, severity, or fire behavior can damage these systems or the services they provide. Repeated fires may lead to degradation of permafrost or ancient organic matter layers. Changes to soil conditions due to fire can have cascading effects on lake chemistry. During plant community recovery from fire, there may be less forage for animals.

More Information:

• Learn more on our Fire Ecology page
• Fire Effects Monitoring
• Studying Wildfire

 

Ecosystems After Fire

Fire is a natural part of the cycle of the boreal forest. It provides renewal and change to the species that call the forest home. Below are photos that highlight successional changes after fire and show the natural cycle of ecosystem.

 

2002 vs. 2007 Otter Creek Fire

Left image
Credit: NPS Alaska Fire Management

Right image
Credit: NPS Alaska Fire Management

In 2000, the Otter Creek Fire burned 10,071 acres. In 2002, park staff investigated burn severity and found there was low to moderate burn severity at the pictured site, evident because the ground did not burn to mineral soil and much of the vegetation re-sprouted. However, the fire killed the black spruce trees that formed the canopy. In 2007, park staff re-measured the plot, now 7 years post-fire. Low shrubs had grown denser, and over 2,600 black spruce seedlings and some birch trees had established. Since birch trees tend to grow faster than spruce, they are more visible in the lower photo. Over the next 30-50 years, under the current fire frequency cycle, it is likely these spruce seedlings will grow and re-form a black spruce forest.

 

Left image
Credit: NPS Alaska Fire Management

Right image
Credit: NPS Alaska Fire Management

This photo pair shows the effects of the 2001 Herron Fire (6,248 acres) one-year (left photo) and six-years (right photo) post-burn. This area burned with moderate to high severity as evident by the complete loss of the canopy. Nevertheless, abundant herbaceous vegetation and mosses have already colonized the resultant bare soil.