FIRE FACTS

 
WILDLAND FIRE

What is Wildland Fire?

A wildfire, also commonly referred to as wildland fire, brush fire, forest fire, or bush fire, is an unintentional and uncontrolled fire in an area with flammable vegetation. 

Fire Triangle

The fire triangle also called the combustion triangle, comprises the three elements required to start and maintain a fire. The three components are heat, fuel, and oxygen. The fire triangle will collapse if just one of these components is removed, extinguishing the fire.

  1. For ignition to occur, a heat source is required, and different materials have varying 'flashpoints,' or the lowest temperature at which they ignite.

  2. Houses, forests, and structures contain combustible materials such as paper, oil, wood, and fabrics. Any of these can be used as fuel and will keep a fire going. There wouldn't be fire if there were nothing to burn. Some materials are more flammable than others. Fuels are the most challenging side of the fire triangle to remove, so it's better to store or manage them properly to prevent them from becoming a fire hazard.

  3. Given that oxygen makes up 21% of the atmosphere, there is ample to start a fire if the other two ingredients are present.

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Types of wildland fires

Forest fires can be classified into three categories:

  • Crown fires burn trees all the way to the top of their branches. These are the most deadly and ferocious wildfires.

  • Only surface debris and duff are burned in surface fires. These are the simplest fires to extinguish and produce the least amount of forest damage.

  • Ground fires (also known as underground or subsurface fires) start when deep layers of humus, peat, and other dead vegetation become dry enough to burn. These fires burn slowly, but they can be difficult to extinguish or completely control. Occasionally, especially during periods of persistent drought, such fires might smoulder underground all winter and then resurface in the spring.

Causes of wildland fire

The fire season typically lasts from April to October, with the busiest months being mid-May to August. Catastrophic fires are more likely to occur during periods where the weather is hot, dry, and windy.

Lightning strikes are responsible for just under half of all wildland fires in Canada, yet they burn over 67 percent of the land. This is due to two key factors:

  • Lightning-caused fires frequently occur in isolated locations where human life, property, and timber assets are unaffected. As a result, fire suppression in these places may be purposefully limited, allowing fire to play its natural role.

  • Multiple lightning strikes might occur simultaneously, requiring agencies to make difficult decisions about where to dispatch available firefighting staff and equipment.

Humans are responsible for slightly more than half of all wildfires in Canada, primarily in densely populated forest and grassland areas.

 
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FIRE BEHAVIOUR

What is Fire Behavior?

Fire behaviour refers to the manner in which fuel ignites, flame develops and fire spreads. In wildland fires, this behaviour is influenced by how fuels (such as needles, leaves and twigs), weather and topography interact.

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The fire behaviour triangle has three components, fuel, weather, and topography. The weather is the most variable and unpredictable of the three factors. It is critical to be aware of present and expected weather conditions in order to be prepared to control and combat fires. The fire behaviour triangle describes how fire behaves once it has begun. For responders and homeowners alike, understanding the complexities of how these components interact is critical.

There are elements that determine how fire behaves under each key component of the fire behaviour triangle. Any change in one variable can cause the fire to behave in an unanticipated manner, and this can happen quickly. 

Weather

The weather has the most considerable influence on the behaviour of flames. The elements of the weather component that have the most significant impact on fire behaviour are as follows:

  1. Wind plays a significant role in fire behaviour, especially in catastrophic wildfires. More oxygen is blown into the fire by the wind, causing it to burn hotter. Wind can also propel flames into unburned fuels, resulting in the start of new fires.

  2. The amount of precipitation and humidity influences a fire's behaviour. For example, if it is raining heavily and there is a wildfire, the rain may aid in extinguishing the fire.

  3. Both the temperature and the fire can cause fuels to dry out, making newly dried fuels available for the fire to spread.

Topography
  1. Slope - The rate and direction in which a wildfire spreads is affected by the steepness of a slope. Uphill fires burn faster than downhill fires, and the greater the slope, the faster the fire will burn. 

  2. A slope's aspect is the compass direction it faces. The amount of sunlight that a slope receives is influenced by its aspect. South-facing slopes get more solar radiation than north-facing slopes in the northern hemisphere, which can influence microclimate and vegetation differences. As a fire spreads to different slopes, its behaviour can change dramatically.

  3. Terrain factors can influence airflow. Mountains and valleys channel and direct the wind in their respective areas. Wind velocity will increase as the wind is forced into a tight valley or canyon.

Fuel

Anything that will burn in a fire would be considered a fuel. Grass, trees, mounds of leaves or other debris, and, worst of all, homes or properties fall into this category. Ground fuels, surface fuels, ladder fuels, and canopy fuels are the four types of fuels.

  1. Ground fuels are found just beneath the surface of the ground and can burn for miles; however, they usually burn relatively slowly.

  2. Surface fuels are materials such as pine needles, leaves, grass, etc., that burn on top of the ground.

  3. The ladder fuels are what cause the fire to progress from the surface to the crown.

  4. Crown fuels burn in the treetops and are challenging to control and extinguish.

 

Following are a few elements of fuel that affect fire behavior:

  1. The arrangement of fuels has a significant impact on how fire behaves. Fuels that are loosely arranged will ignite quicker and burn more intensely because the fuel dries faster, and also, more oxygen is available among the fuel for the combustion process. Less oxygen will be accessible as fuels are compressed, and less wind will be able to penetrate the mass to carry moisture away. They take longer to dry and will be wetter as a result. As the fuel becomes more compressed, it begins to behave like a large fuel, requiring more time and heat to dry and burn. Fuels higher off the ground, like brush and hanging pine needles, are loosely structured and dry out quickly. The fire can extend vertically into the high brush and even the crown of the overstory if the volume is sufficient to carry flames and they are close enough for convective and radiant heat to pre-heat them to their ignition level. The fire may not continue to burn if the horizontal arrangement becomes patchy, except on the most extreme days when the radiant heat is high enough to pre-heat the fuel across the open sections. A good example is scattered logging debris.

  2. Fuel moisture - Another factor that influences fire behaviour is the quantity of moisture in the fuels. When the moisture content of the fuel is low, like in grassland, the fire will burn hot and rapidly, depending on the wind. The faster the fuel burns, the drier it is. The wetter the fuel, on the other hand, the slower it will burn.

  3. Fuel load - The amount of fuel has a significant impact on how fire behaves. A low-intensity, creeping fire can emerge from minimal amounts of fuel. Large amounts of fuel, on the other hand, could result in a difficult-to-control blow-up fire. The more fuel that is burned, the greater heat is generated. In general, the more fuel there is, the more fierce the fire will be.

 
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FIRE MANAGEMENT

What is Fire Management?

Fire management is the process of planning, preventing and fighting fires to protect people, property and the forest resource.

The practice of planning, preventing and fighting fires to safeguard people, property, and the forest resource is known as fire management. It also involves the use of fire to achieve forestry, wildlife, and land-use goals.

Canadian attitudes to fire have changed markedly over the years. For much of the 20th century, putting out fires (known as fire suppression) was the goal. Often costly to achieve, it was generally successful, though to the detriment of ecological values.

By the 1970s, recognition of fire’s ecological benefits had grown. Suppression, as forest managers were coming to realize, was not always necessary or desirable. Today, fire management includes a range of levels of fire suppression, from complete extinguishment to little or no intervention at all.

The decision to fight a fire or leave it to burn out naturally is based on a hierarchy of priorities set by the government agency responsible for fire management where the fire is burning. In most of Canada’s forests, provincial and territorial agencies have the responsibility for wildland fire management. Areas where federal government agencies are responsible include national parks and military bases.

High-priority areas for protection include residential areas, high-value commercial forests, and recreational sites. Low-priority sites are generally wilderness parks and remote forests of limited economic value—although protection of rare habitat, culturally significant areas, and similar values will influence suppression decisions.

*** need more on Fire Management. paragraph above was taken from CFS(https://www.nrcan.gc.ca/our-natural-resources/forests/wildland-fires-insects-disturbances/forest-fires/fire-management/13157), could we get permission or should we find another way to write this?

 
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FUELS MANAGEMENT

What is Fuels Management? 

Fuel management refers to changing the structure and composition of a forest to reduce the fuel available to burn in a wildfire

Why are fuels managed?

Wildland fires help maintain healthy ecosystems but also cause damage. The size and intensity of wildland fires are expected to increase in the coming years.

Wildland fire plays an important ecological role in maintaining healthy ecosystems. However, wildland fires also burn millions of acres each year, cost billions of dollars, damage homes and critical natural resources, and result in deaths. The size and intensity of wildland fires have increased in recent decades, partly due to climate change, and many scientists and researchers expect fires to become larger and more severe in the future.

Various ways that fuels are managed

Prescribed burning

Prescribed burning can also be used to enhance wildlife habitat or achieve other resource management goals. Forest managers occasionally use prescribed fire to cope with the fuel load that has accumulated in forest regions. "Prescribed fires" are fires that are carefully planned and executed. They're a multi-purpose management tool that's typically used to prevent major, uncontrollable fires.

Large fires cause the majority of the land burned in Canada, and they pose the greatest damage to Canadians' property, health, and safety.
Prescribed burning can also be used to enhance wildlife habitat or achieve other resource management goals.

Fighting fire

Forest and grassland fires are safely and effectively responded to by highly trained personnel using well-designed tools and high-performing equipment. Firefighting typically involves a combination of ground firefighters and aerial firefighting aircraft.

Fuel modification

Typically applied to areas in the wildland-urban interface. Wildland/urban interface describes any area where combustible wildland fuels are found adjacent to homes, farm structures, and other outbuildings. FireSmart Canada has developed manuals and guidelines to set standards across Canada. The goals for FireSmart Canada are twofold: to improve communication with stakeholders; and organize programs and assets into a logical, manageable structure based on three pillars – homeowners, neighbourhoods, and communities.

*** other ways fuel is modified? More ways?

 
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PEOPLE & FIRE

What relationship have fire and culture had?

Indigenous peoples around the world have managed fire for thousands of years. Through changing climatic conditions and in many different ecosystems, they have used fire to survive, adapt to local environmental conditions, and increase the abundance of resources and landscape conditions that they favor. 

***should I talk to Amy C about this?

 
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RESOURCES

Find more wildland fire related information and the organizations that work with wildland fire in Canada