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Wildfires have captivated our attention for centuries, but understanding wildfires is crucial for prevention, mitigation, and reclamation.  With a focus on evidence-based research and expert insights, we aim to foster a deeper knowledge of the complexities of wildfires and their ecological impact.


What is wildfire?

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

Fire Triangle

The fire triangle, also known as the combustion triangle, is made up of the three elements needed to start and sustain a fire. The three components are heat, fuel, and oxygen. The fire triangle will collapse if any one of the components is removed, extinguishing the fire.

  1. A heat source is required for a fire to ignite. Different materials have varying ‘flashpoint”- the lowest temperature at which they ignite.

  2. Fuel: Plant matter, or grasses trees, shrubs, and other living and nonliving materials such as houses and other structures contain combustible materials. 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. 

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

Types of wildfires

Wildfires can be classified into three categories:

  • Crown fires involve the burning of trees up to their uppermost branches. These wildfires are known to be highly dangerous and intense.

  • Only surface debris and duff are burned in surface fires. They are relatively easier to put out and cause minimal damage to the forest.

  • 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 may smoulder underground all winter and then resurface in the spring.

Causes of wildfire

The fire season in Canada typically lasts from April to October, with the busiest months being mid-May to late August. Periods characterized by hot, dry, and windy weather are more prone to experiencing catastrophic wildfires.

Lightning strikes are responsible for just under half of all wildfires in Canada, yet they cause over 67 percent of the area burned. This is due to two key factors:

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

  2. 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. Human-caused wildfires can result from activities such as campfires, off highway vehicles, discarded lit cigarettes, equipment malfunctions, arson, trains, power line failures, fireworks, agricultural burning, outdoor burning, and negligence.

Both lightning and human-caused fires require a dry forest environment to propagate. Dry conditions create an environment where fires can easily start and rapidly spread, increasing the risk and severity of wildfires.

Wildfire Behaviour
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What is wildfire behavior?

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


The wildfire 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 wildfire 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. 


The weather has the strongest influence on the behaviour of flames. The elements of weather that have the most significant impact on fire behaviour are:

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

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

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

  1. Slope angle - 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 uphill. 

  2. The aspect of a slope refers to the compass direction in which the slope is facing and affects the amount of sunlight it receives. In the northern hemisphere, slopes facing south receive more solar radiation compared to those facing north. This influences various factors, such as the timing of snowmelt, microclimate conditions such as temperature (drying), and variations in vegetation.

  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.


Anything that can burn in a fire is 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 usually burn relatively slowly but may smoulder persistently and be difficult to extinguish.

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

  3. The ladder fuels are what enable a fire to easily progress or “climb” from the surface to the crown. Examples of ladder fuels are tall shrubs, small and medium-trees, and low-hanging limbs.

  4. Crown fuels are in the treetops or “canopy” and are challenging to control and extinguish from the ground.


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

  1. Fuel size relates directly to the amount of heat required for fuels to reach ignition temperature (flashpoint). Fine fuels (small twigs, leaves, needles, grasses or other light weight, small diameter materials >5cm) have more exposed surface area in relation to their volume and consequently dry out faster than larger fuels. Fine fuels burn rapidly and play a huge role in ignition and rate of spread. Coarse fuels (logs, tree stumps and trunks, large tree limbs) require more heat for ignition and burn slower and for a longer time period than fine fuels.

  2. The arrangement of fuels has a significant impact on how fire behaves. Fuels that are loosely arranged will ignite quicker and burn more intensely as more surface area is exposed. This allows the fuels to dry and heat faster, while also providing space for air, and thus oxygen among the fuel.. As fuels are compressed, less oxygen will be readily accessible, less wind will be able to flow through the mass to carry moisture away, and a heat source is only able to directly interact with the outside of the mass. As  fuel becomes more compressed, even fine fuels can begin to behave like a course fuel, requiring more time and heat to dry and burn. Vertical arrangement is important for determining the potential fire type (ground, surface, crown) and behaviour. Fuels off the ground, like tall grasses, brush, and hanging dead branches and pine needles, are loosely structured and dry out quickly. When there are plenty of ladder fuels, a fire has the potential to move upwards. This happens when the ladder fuels are close to the fire and are heated by the surface fire below; eventually, the fuels catch fire and help carry the flames higher. Horizontal arrangement impacts the way a fire propagates across the landscape. The fire may not continue to spread 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, or they are already sufficiently dry and ready to ignite via ember (firebrand) transport). Some good examples are scattered logging debris, or a fire encountering a waterbody, wetland, or already burnt area.

  3. Fuel moisture - Another factor that influences fire behaviour is the amount of moisture in the fuels. When the moisture content of the fuel is low, like in a dry desiccated grassland, the fire may burn hot and rapidly, depending on the wind. The drier the fuel, the easier it will ignite and the faster it can burn. The wetter the fuel, on the other hand, the harder it is to ignite and the slower it will burn.

  4. 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 available fuel, on the other hand, could result in a difficult-to-control blow-up fire. The more fuel that is burned, the greater the amount of heat generated.  In general, the presence of ample fuel tends to make the fire more intense and active.

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What is wildfire management?

Wildfire management is the process of planning, preventing and fighting fires to protect people, and the things they value such as property, cultural sites, biodiversity, infrastructure, and other forest resources.

Wildfire management in Canada refers to the strategies, policies, and practices implemented to prevent, monitor, control, and mitigate the impact of wildfires within the country. Canada, known for its vast forests and diverse ecosystems, experiences a significant number of wildfires each year. Wildfire management practices can vary across Canada due to variations in ecosystems, climate conditions, and jurisdictional responsibilities. Here are several ways in which wildfire management is carried out:

Prevention and Mitigation: Wildfire prevention and mitigation involves measures to reduce the likelihood of fires occurring or impacting areas of value. This includes public awareness campaigns, enforcing fire bans, monitoring weather conditions, and implementing regulations for activities that may increase fire risks, such as campfires or logging operations. Other examples of prevention and mitigation efforts include integrating defensible spaces, fuels management (FireSmart), hazard reduction and prescribed burning, and having up to date wildfire management and evacuation plans to help aid decision making should an incident occur.

Detection and Monitoring: Early detection of wildfires is crucial for rapid response. Canada uses a variety of tools for wildfire monitoring, including aerial patrols, satellite imagery, remote sensing technologies, ground-based patrols, and lookout towers. These systems help identify and locate fires, allowing authorities to respond quickly.

Suppression: Once a wildfire is detected, decisions are made on whether to action or monitor the fire. If the fire threatening a value on the landscape, firefighting crews may be dispatched to contain and extinguish the fire. Firefighters, often supported by aircraft and heavy equipment, work to establish fire breaks, remove fuel sources, and utilize prescribed burns to manage the fire's spread. Canada has highly trained provincial and territorial firefighting
agencies that collaborate during larger incidents.











Coordination and Management: Wildfire management in Canada involves coordination among multiple agencies and levels of government. This includes federal, provincial, and territorial governments, Indigenous communities, and various stakeholders. Integrated wildfire management plans are developed to ensure effective response and resource allocation.

Research and Technology: Continuous research and technological advancements play a crucial role in improving wildfire management. Canada invests in research to understand fire behaviour, develop better fire prediction models, and explore innovative firefighting techniques. Technologies like fire modeling, real-time fire mapping, and improved communication systems enhance wildfire response efforts.

Community Engagement: Engaging communities is vital to wildfire management. Public education campaigns promote fire safety and responsible behaviour, such as proper campfire practices and reporting suspicious activities. Collaboration with Indigenous communities, municipalities, industry is also essential, as they carry extensive traditional knowledge and land management practices that can contribute to effective fire and land management.

Post-Fire Recovery: After a wildfire, efforts focus on assessing damage, rehabilitating affected areas, and supporting affected communities. This is typically the longest period of a wildfire incident and can span over months or even many years.

Airtanker effectiveness

Learn about the various types of airtankers used in Canadian wildfire suppression. Melanie Wheatley is a PhD Candidate at the University of Toronto studying airtanker suppression effectiveness.


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?

Wildfire plays an important ecological role in maintaining healthy ecosystems. However, as they spread over millions of acres annually they can result in damage to valuable assets. The direct costs of fire suppression efforts amount to billions of dollars annually, and wildfires have the potential to harm homes, infrastructure, essential natural resources, and tragically, even lead to loss of life.

Various ways that fuels are managed

Prescribed burning

Prescribed burning can be employed to enhance wildlife habitat or accomplish other resource management objectives. Forest managers may utilize prescribed fire as a means to address the substantial fuel load that has accumulated in forest regions and help mitigate future risk. Prescribed fires are meticulously strategized and executed fires. They serve as a versatile management tool primarily employed to deter the occurrence of significant unplanned fires that are exceedingly challenging to extinguish.

Cultural burning

Cultural burning refers to the intentional and controlled use of fire by Indigenous peoples to maintain and restore ecosystems, promote biodiversity, and enhance cultural practices. Indigenous communities in Canada have a long history of using fire as a tool for land stewardship. They recognize that fire can play a crucial role in maintaining healthy forests, grasslands, and wetlands by promoting the growth of certain plant species, reducing fuel loads, and preventing the spread of larger wildfires. Cultural burning is deeply rooted in Indigenous knowledge, traditions, and spiritual beliefs, and it is seen as a holistic approach to land management.

In recent years, there has been a growing recognition of the importance of incorporating cultural burning practices into modern land management strategies in Canada. Efforts have been made to engage with Indigenous communities and support their knowledge and expertise in utilizing fire as a land management tool.
 Indigenous Nations have recently been asserting their inherent and/or treaty rights by assuming leadership roles in fire management in their territories.

Fuel modification

Typically, fuel modification is applied to areas in the wildland urban interface. The wildland urban interface is the area where human development meets or intermingles with the natural environment. FireSmart Canada has developed manuals and guidelines to set risk reduction 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. These are some ways fuel modification is applied in these regions to mitigate the impact of wildfires:

  1. Defensible space: Creating defensible space involves modifying vegetation and clearing areas around buildings in the urban interface to reduce fuel continuity. This includes clearing trees, shrubs, and accumulated needle and leaf litter from the immediate vicinity, but also requires the removal of other human introduced fuels such as fire wood piles, mulch or straw bedding, flammable decorative arrangements, etc. This practice aims to create a buffer zone that minimizes the risk of fire spreading from nearby vegetation to structures.

  2. Fuel Breaks: Fuel breaks are strategically established in the urban interface to impede the spread of wildfires. These cleared areas or modified vegetation strips act as barriers, reducing the availability of fuel and helping to protect communities and infrastructure.

  3. Hazard reduction and Prescribed Burning: Hazard reduction and prescribed burning are conducted in the wildland urban interface and strategically selected surrounding areas under controlled conditions to reduce fuel loads and minimize the risk of severe wildfires. This technique aims to remove excess vegetation, provide strategic breaks for future suppression operations, and decrease the potential for fire to reach homes and other structures.

  4. Fuel Reduction Treatments: Fuel reduction treatments involve selective vegetation thinning and removal in the urban interface. By reducing fuel loads and creating spacing between vegetation, this practice helps mitigate the intensity and speed of wildfires, enhancing the safety of urban areas. Different types of vegetation exhibit varying levels of susceptibility or resilience to fire. Opting for native trees and plants that are naturally more fire-resistant is also a beneficial approach.

  5. Public Education and Awareness: Educating residents in the wildland urban interface about fire safety, responsible landscaping practices, and the importance of fuel management is crucial. Raising awareness about the risks of wildfires and promoting responsible behaviours minimizes the chances of human-caused fires and ensures the resilience of communities in the face of wildfires.


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. 

Fire has played a significant role in shaping the culture and history of Canada. Indigenous peoples in Canada, such as the First Nations, Inuit, and Métis, have long recognized the importance of fire in their cultural practices and land management. Traditional burning techniques were used to maintain ecosystems, enhance biodiversity, and facilitate the growth of important plant species. Fire was also integrated into spiritual and ceremonial practices, symbolizing purification, renewal, and connection to the natural world. However, the arrival of European settlers in Canada led to significant changes in fire management practices. European perspectives often regarded fire as a destructive power to be managed and suppressed, resulting in policies focused on extinguishing wildfires and discouraging traditional burning practices. This fire exclusion strategy disrupted the natural fire regimes, resulting in ecological imbalances and an accumulation of flammable materials. Additionally, the use of fire to foster a mutually beneficial connection between numerous communities and their environment was rendered unlawful. In recent years, there has been a growing recognition of the importance of incorporating Indigenous knowledge and practices into fire management strategies, promoting a more balanced approach that respects both cultural traditions and ecological health. This shift highlights the evolving relationship between fire and culture in Canada, emphasizing the need for collaboration, conservation, and cultural preservation.

What is the main source of ignition for wildfires in Canada?

While human activities are responsible for the majority of wildfires worldwide, lightning-caused wildfires have a significant impact in Canada. Canada experiences approximately 3,000 wildfires ignited by lightning annually. These lightning-caused fires make up half of all wildfires and result in the majority of the area burned in Canada. Lightning strikes can occur throughout the year, but in Canada are most common during the hot and humid summer months, particularly in July and August.

In what conditions can lightning ignite wildfires?

During thunderstorms, lightning can jump between clouds and from clouds to the ground. It is the cloud-to-ground lightning strikes that have the potential to start fires. Not every lightning strike leads to a wildfire. In fact, in many regions of Canada, less than one out of approximately 200 lightning strikes cause wildfires. The likelihood of a wildfire starting depends on the dryness of the forest and its readiness to burn. If the weather has been hot and dry for an extended period, the forest floor becomes dry and susceptible to ignition. When lightning strikes this dry fuel, it often ignites a new wildfire. The amount of rain accompanying the lightning storm becomes crucial in determining whether the strike will start a wildfire, and if it will sustain or be extinguished.

In many thunderstorms, the rain is sufficient to wet the surface fuels, preventing the flames from spreading in the forest. However, due to the immense energy transferred into the ground by lightning strikes, smouldering ignitions can occur deeper in the forest floor where the rain did not reach. These smouldering fires spread slowly and can remain active and often undetected for days or even weeks, waiting for the surface fuels to dry out again. Once the surface fuels become dry enough, these smouldering fires can emerge and spread rapidly through the forest as flaming wildfires. This process, known as "holdover," refers to fires burning slowly beneath the forest floor until conditions are favourable for surface spread.

Can lightning be responsible for numerous new wildfires appearing at one time?

In a single day, a large thunderstorm passing through a forested area may produce tens of thousands of cloud-to-ground lightning strikes, potentially leading to hundreds of holdover fires waiting for favourable conditions to spread. If the weather changes and becomes hot, dry, and windy, these holdover fires can all emerge simultaneously, resulting in numerous new growing wildfires seemingly appearing all at once. This sudden influx of wildfires can overwhelm wildfire management agencies, as it becomes challenging to effectively deploy fire crews and aerial resources to suppress them.

Wildfire managers have access to technology that allows them to track the occurrence of lightning strikes and estimate the dryness of forest fuels. By using these tools and analyzing weather patterns, they can predict when larger clusters of lightning-caused wildfire arrivals might occur in an area. However, even with the best planning, the number of new lightning-caused wildfires resulting from significant storms can surpass the capacity of a single wildfire agency to manage effectively.

Wildfire smoke

What makes up wildfire smoke? How does smoke travel such far distances? How can you protect yourself from wildfire smoke? Where can I get information about current smoke conditions? Brian Wiens, Managing Director at Canada Wildfire, answers these commonly asked questions in this video:

lightning conditions
How do wildfires affect our water?

Many types of natural environments, like forests, wetlands, and grasslands, play an important role in providing us with abundant and clean water. Changes to water quantity and quality after a wildfire can widely influence rivers, lakes, and seas, affecting our ability to use these resources. 

Storms that occur directly after a wildfire can trigger various water-related hazards, such as flash floods, water pollution, and debris flows that can damage aquatic ecosystems, communities, and infrastructure. Although the initial impacts of a wildfire on water may lessen over time, they can persist for a considerable period, even lasting for decades. It is crucial to closely monitor these effects to manage them effectively, minimizing disruptions to human life and natural ecosystems. 

This does not mean that wildfire impacts on water resources are always negative. Wildfires can rejuvenate freshwater habitats and promote biodiversity. Smaller, less intense wildfires remove excess ground vegetation, which can help prevent extreme wildfire events from happening within the ecosystems that provide us with water resources.

The 2015 Stouts Creek Fire in Oregon led to more runoff and erosion. (Credit: Kevin Bladon, OSU)

Forest Road

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

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