Not all flame's the same

Fire has played a significant role in shaping landscapes throughout history, sparked by both lightning and the intentional use of fire by Indigenous peoples.

Fire enabled people to manage and adapt to their local ecosystems, helping them produce food, tools, materials and medicines, as well as maintain prairies, clearings and travel routes. It also helped reduce the risk of larger, more destructive fires by preventing the accumulation of excess fuel.

Beyond human use, fire serves vital ecological functions, such as clearing dead vegetation, recycling nutrients, creating habitats for plants and animals, promoting germination and new growth and controlling insects and diseases.

• Fuel is any living or dead organic material that can ignite and burn, from grasses to shrubs to trees.
• A fire regime refers to the pattern, frequency, intensity and type of fire that typically occurs in a specific ecosystem or landscape over a long period of time. It describes the natural role of fire in maintaining the health and balance of ecosystems and how fire behaviors, such as how often fires occur, their size, the severity of the burning and the seasons in which they happen, shape the environment. Fire regimes are influenced by factors like climate, vegetation, topography and human activities.

Oregon is a very diverse state from the coast to the Cascade Mountains and the Great Basin. Because of this, it makes sense that the way fire behaves also varies across the state. In other words, fire happens in different patterns and has different effects. This resource explains the role of fire in seven of Oregon’s ecoregions.

• Ecoregion: A geographic area where environmental conditions such as specific vegetation patterns, climate, land formations and soils are similar.

Fire’s role and its impacts vary due to:

• Fuel type: Species, forms, sizes and arrangements of fuels that will burn similarly.
• Fuel continuity and distribution: The extent of uninterrupted areas of fuels and how they are spread across the landscape (continuous or patchy), which affects a fire’s ability to sustain combustion and spread.
• Fuel loading: The amount of fuels present expressed as weight per unit area, such as tons per acre.
• Fire resistant: Some vegetation (fuels) can experience fire without sustaining major damage due to features such as thick bark on trees.

Other fire ecology terms that describe fire’s actions and effects are:

• Fire behavior: Refers to how a fire responds to the combined influences of fuel, weather and topography. This includes factors such as how quickly the fire spreads, how much heat it generates and how much vegetation it consumes.
• Severity: The effects of a fire on the environment, typically referring to the loss of vegetation or soil impacts.
• Intensity: The amount of energy (heat) a fire produces, often described by flame height, rate of fire spread, temperature and duration. High fire intensity typically leads to more significant damage and longer-lasting effects. In contrast, low-intensity fires tend to be less destructive and may burn more slowly.

People are an important part of fire ecology. We interact with fire in many ways, such as trying to prevent it or reducing its effects. Our presence on the land also affects how fire behaves and the risks it creates.

Terminology used throughout this resource to describe this includes:

• Colonization: Control by one power over an area or people. In the place now called Oregon, Indigenous people were displaced from their lands and their relationships with fire were disrupted by settlers who introduced agriculture, timber management and other land uses.
• Fire exclusion: The policy of suppressing all wildfires to the extent possible.
• Wildland–Urban Interface: The area where structures and other human development meet or intermingle with undeveloped wildland or vegetative fuels.
• Fuel break: A natural or constructed area with little or no fire-resistant vegetation that can stop or slow fires.
• Prescribed fire: Intentional, planned use of fire to achieve management or ecological objectives.
• Broadcast burning: The application of prescribed fire across an area, in contrast to piles.