Fire’s role in in Idaho forests

Wildfires: from friend to foe?

Fire historically has played a natural role in forest ecosystems — it can both destroy and create habitat.  When it burns through dry underbrush, it allows sunlight to reach the forest floor, encouraging the growth of native species. Most young, healthy trees are resilient enough to survive a forest fire.  Burned trees offer homes for birds and small mammals. Nutrients from burned vegetation leach into the soil to fuel the birth of new plants.

But human response to fire and the resulting conditions, have changed the role of fire in the forest ecosystem from friend to foe.


Today’s wildfires are the most feared components of Idaho’s forest threats. In the last 100 years, fires were put out as quickly as possible. Fire suppression has created forests that are denser with more understory vegetation.  When a fire ignites, it shoots up quickly from the forest floor to the treetops creating intense heat that burns everything in its path. Add more residential developments in these forests and you have the recipe for huge economic and personal losses.

FOREST FACT: In Idaho, more than 686,000 acres burned in 2017.

FOREST FACT:  According to the Insurance Information Institution, Idaho ranked number two in the nation for the percentage of homes (26%) at a high or extreme risk from wildfires in 2018.

Fire In Forest Ecology

Forests exist in a complex combination of age classes and species mixtures. Many scientists agree that a healthy forest is able to renew itself, recover from a large range of disturbances, and retain its ecological resilience while meeting the current and future values, uses, products, and services desired by people.  

To learn more about the environmental benefits of forests, click here.

Watch a short video about forest fires – their role in forests, why they’ve become so severe and what can be done.  Click here.


History of Forest Fires in Idaho

Fires have always been a part of Idaho’s forests, whether natural or human-caused.  In fact, fire historically played an important role in maintaining forest health, particularly in dry pine-type forests and high elevation forests.  Periodic, low-intensity ground fires served to reduce underbrush and forest density.


In August of 1910, fires burning in northern Idaho blew up into a massive conflagration, generating hurricane-force winds that sent flames roaring and jumping through northern Idaho and western Montana, destroying more than three million acres of forestland and killing 86 people in just two days.  As a result of that fire and other massive wildfires across the country—burning up to 50 million acres annually in the early 1900s – Congress assigned fire suppression responsibilities to the Forest Service.

Learn more about “The Big Burn” in a documentary from PBS’s American Experience.  Watch now.

In 1930, more than 190,000 fires burned more than 52.3 million acres in the US, according to the National Interagency Fire Center.   Effective fire suppression and prevention efforts, starting in the 1930s, resulted in an unhealthy accumulation of forest fuels.  In the absence of thinning or controlled burning to reduce fuels, the potential for high severity fires in these forests has greatly increased.  

Fire Threats Today

Nearly a century of fire suppression in Idaho has allowed the growth of unnaturally dense vegetation, particularly in the drier pine forests throughout the state.  About a third of our forests are at high risk of uncharacteristically intense fire. Nearly 40% of our forests are at moderate risk. Only 28% is within or near historical conditions.

Click the graphs below to view acres burned over time in US.









In 2011, the University of Idaho Policy Analysis Group predicted that high forest mortality and low timber removal rates in the Western states promised hazardous fuel accumulations and big fires.  Read the report here.


A large percentage of Idaho’s forest are at dangerously high risk of severe fire because of dense and overcrowded conditions and dead and dying trees.  At-risk forests burn more intensely and are more likely to destroy existing wildlife habitat, threaten homes and watersheds, damage soils, and emit large amounts of carbon dioxide and other pollutants. 

Removal (mortality, harvesting, insect, disease and fire damage) versus net growth (growth less natural mortality) greatly exceeds removals (harvests) in Idaho forests, particularly on National Forests.  This condition is unsustainable and will ultimately be brought into balance by nature through insects, fire or a combination of both. Maintaining forest health is a matter of establishing sustainable stand conditions and reducing risks.  Management of at risk stands has significant economic costs, unless it is coupled with the production of forest products.

The Cost of Fire

Costs associated with fire suppression have greatly increased while timber harvests in many of these areas have greatly decreased.  Click the image to view the federal costs associated with fire suppression in the US from 1985-2017.


FOREST FACT: In 2017, it cost the federal government nearly $3 billion to suppress wildland fires across the U.S.

FOREST FACT:  The 2018 forest fire season cost the State of Idaho $20 million.

Wildfires also burn productive timberlands, make recreation and tourism unappealing and affect agricultural production. Smoke from fires has an adverse effect on health and safety. Depending on the severity and location of a wildfire, post-disaster recovery can come with a considerable price tag. Factors that affect state and local budgets in the long-term include replacement of lost facilities and associated infrastructure,  watershed and water quality mitigation and sensitive species and habitat restoration.




Read about current fire conditions in Idaho here.

To read the State of Idaho 10-Year Fire Data from 2007-2017

Learn about fire ecology and management in Idaho from Idaho Firewise

Learn about forest fire terms from the US Forest Service

View statistics about wildfire in the US from the Insurance Information Institute

Read the “National Report of Wildland Fires and Acres Burned by State

Read “The True Cost of Wildfire in the Western U.S” from the Western Forestry Leadership Coalition

Read “State Funding for Wildfire Suppression in the Western U.S.” from the University of Idaho

Read a 2016 report from the Department of Lands called “Managing Fire on Lands Protected by the State of Idaho”

Download a fact sheet about why some forest fires are more intense 

Download a report called “State of Fire in Oregon’s Forests”