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What is a Wildfire? Exploring Types and Definitions

what is a wildfire graphic with wildfire burning in the background

In this article


Types of Wildfires

Wildfire Definitions

How do Wildfires Start?

Impact of Wildfires



Wildfires are a fascinating natural phenomenon that has intrigued people for centuries. In this article, we'll explore the basics of wildfires, including what causes them and how they affect the environment. Let's start by asking: What exactly is a wildfire?

The National Geographic defines wildfires as uncontrolled fires that burn in wildland vegetation, often in rural areas. They can burn in forests, grasslands and other ecosystems and have been a part of life on Earth for hundreds of millions of years.

Wildfires consume natural fuels and flammable materials and their spread is often affected by environmental factors such as wind speeds and topography. Though there are wildfire hotspots, they are not a phenomenon specific to a particular region or climate. Unfortunately, they are a significant environmental, societal and economic problem that’s only getting worse.

Though these fires can be started naturally as a result of occurrences like lightning strikes, up to 85% of wildfires are caused by humans. A small portion of rural fires are controlled or prescribed burns and these can sometimes be beneficial. However, the fact remains that the vast majority of fire incidences are both human-caused and potentially ruinous.

How Do Wildfires Start? What Causes Wildfires? | Dryad Networks
graphic stating that 84% of wildfires in in the united states are caused by humans

In places like California and Australia, forest fires are an annual occurrence. These regions often see hot summers with little rainfall and humidity followed by dry autumns after the end of the wet season. This combination of dry vegetation and low rainfall make these areas prime locations for massive outbreaks. Climate change is undoubtedly making things worse, with warmer temperatures altering weather conditions and increasing the frequency and severity of fires.

Let's look at some definitional issues before exploring wildfires in more detail, including how they start and what makes them so dangerous to society.

The Three Types of Wildfires

The three types of wildfire are surface, ground, and crown fires. Surface wildfires burn the top layer of dead plants and debris. They also burn some or all of the plants growing beneath the trees. The understory is the underlying level of vegetation such as seedlings, saplings and understory shrubs.

Surface wildfires move rapidly through an area and can reach speeds of up to fourteen miles-per-hour. However, the soil’s moisture often prevents the ignition of the humus layer, protecting the soil and the organisms within it.

graphic for statistic stating that wildfires can reach speeds that exceed 14 miles per hour

Ground fires can be more damaging since they can consume almost all of the organic cover within an area. These fires are common during periods of severe and prolonged drought when the entire organic layer dries. Though slower moving than surface fires, they can burn for weeks or even months and often won’t stop until they’re extinguished or they run out of fuel.

Crown fires occur within the crowns of trees themselves and can often spread from tree to tree. They are often started by surface or ground fires reaching wooded areas. As you might expect, these fires occur in forests and are more likely to ignite and spread during periods of drought and low relative humidity. Dense and volatile understories can worsen the spread and intensity of crown fires.

Wildfire Definitions - What’s the difference between a bushfire and wildfire? Or the difference between a wildfire and forest fire?

Mentions of wildfires, forest fires, grass fires and bushfires are common, but are there differences between them? Other terms used when referring to wildfires more broadly include brush fire and wildland fire. This picture is often complicated by many agencies and publications using the terms interchangeably.

graphic showing different kinds of wildfires including forest fires, grass fires and bushfires

Where they exist, terminological differences are often related to the type of fuel being burned, and therefore to the where the wildfires are occurring. ‘Wildfires’ is a term often deployed as a catch-all term for the types of fires mentioned below:

Forest fires

Forest fires are large and unpredictable fires that occur in forests, woodlands and shrub lands. Forest fires can be categorized into low-intensity fires, moderate-intensity fires or high-intensity fires.

  • Low-intensity fires start and spread slowly with little smoke. They do not normally kill mature trees but may kill saplings and shrubs. Low-intensity fires may be best left to burn out naturally because they may help to maintain the health of the forest. Prescribed fire mimics low-intensity fire and is used as a means to maintain many ecosystems.

  • Moderate-intensity fires produce more smoke and higher temperatures than low-intensity fires. They can kill trees and damage the forest. Trees that survive moderate-intensity fires may be seriously weakened and become more likely to be blown over by high winds.

  • High-intensity fires are the most dangerous and damaging types of forest fires. They produce a lot of smoke and are difficult to control. They kill mature trees and can destroy the whole forest. High-intensity fires can also kill wildlife and nearby animals including livestock and wildlife such as birds, reptiles and amphibians.

Grass fires

Grass fires are fires that develop in grasslands, savannahs and other open areas. They can also occur in agricultural areas and can quickly consume crops such as corn, rice, wheat and barley. They are capable of burning for long periods, especially in areas with high temperatures and low levels of rainfall.

Grass fires can become more dangerous during periods of drought when there is little rainfall. Since grass is a fine fuel, grass fires often burn faster than forest fires or bushfires. Fires that kill grasslands and crops can reduce the amount of food that is available for grazing animals, with severe knock-on effects for the food chain.


Bush fires are wildfires that occur in the bush, which is a term (most commonly used in Australia) for a wild area of land. Bushfires are generally slower moving than other types, but have a higher heat output.

Like forest fires, bushfires can spread very quickly and destroy large areas of land.

How Do Wildfires Start?

Fires can be started by anything that can ignite, including downed power lines or sparks from machinery, campfires or cigarettes. Fire risk is driven by three main factors - which together make the Fire Triangle:

  • Lots of dry fuel to burn (grass, leaves, branches, and other organic matter)

  • Enough heat to ignite and burn

  • Oxygen in the air

graphic showing the fuel triangle

When it comes to naturally occurring wildfires, the main culprit is usually lightning strikes, which generate heat and cause fires to ignite on the forest floor. Some areas are particularly prone to these kinds of wildfires, such as Canada’s British Columbia, where lightning strikes are responsible for 60% of wildfires.

The devastating 2020 Bay Area Fire which destroyed 5 million acres of land, over 10,000 structures and killed 33 people was also started by lightning storms.

Research suggests that up to 85% of wildfires in the United States are caused by humans, whether intentionally or unintentionally. Human-induced wildfires in the US tripled the length of the region’s fire seasons between 1992 and 2012, from 46 to 154 days.

The most common causes of wildfires are unattended camp and debris fires, discarded cigarettes, and arson.

'How do Wildfires Start?' | Dryad Networks

Impact of Wildfires

Wildfires have the potential to cause catastrophic damage to property, livelihoods and human health. According to the United States’ National Oceanic and Atmospheric Administration, between 1980 and 2021 the United States had 20 wildfire events that caused more than $1 billion in damage, with 16 of these having occurred since 2000.

The United States spends billions of dollars every year fighting wildfires. In 2020 alone, it spent $2.6 billion. And the damage wrought is far from purely financial: more than 1,000 firefighters have died fighting wildfires in the US since 1910.

Another startling statistic is that wildfires alone account for 20% of global greenhouse gas emissions. That's more than all the world's transit emissions combined.

Even communities far away from where wildfires rage cannot escape their deleterious effects. Smoke and fumes from wildfires have been linked to significant health consequences and societal costs, such as hospital admissions and respiratory-related deaths. This is because wildfires greatly reduce air quality and create air pollution from fine particulate matter. These toxic pollutants are then breathed in, leading to respiratory problems, diseases of the lungs, and issues with people's nervous system.

One of the the things that makes wildfires so destructive and frightening is that they can spread very quickly, sometimes travelling at a rate of 14.29 miles per hour or more. It is not a coincidence that 'spread like wildfire' has become an idiom in English-speaking countries. When a wildfire starts to rage, it's usually too late to save anything in its way. In addition to their terrifying speeds, wildfires are also notoriously hard to predict.

While the most obvious effect of a wildfire is damage to forests, infrastructure and buildings, wildfires can also affect the climate. Forests are some of the world’s best storers and sequesters of carbon. When they burn, they immediately release countless tonnes of carbon dioxide into the atmosphere. This in turn contributes to global warming, creating a vicious cycle of increased fire outbreaks and a warming planet.

To delve deeper into often unreported impacts of wildfires and to explore the solutions available to mitigate their devastating impact, we invite you to download our comprehensive whitepaper, 'What Lies Beneath: the hidden truth about wildfire.'

This paper discusses the negative impacts of forest fires. These include harm to the environment, loss of lives, effects on wildlife, and high economic costs. Additionally, it highlights the latest technological advancements and their pivotal role in combating these fires.

'What Lies Beneath: the hidden truth about wildfire' | Dryad Networks

Mitigating Wildfire Risk with Early Detection Technology

In response to the worsening wildfire crisis, innovative solutions that seek to detect wildfires quickly are increasingly coming to the fore. These solutions lean on a range of different technologies, from remote sensing to infrared satellite imagery. Dryad’s own solution is a solar-powered mesh network of AI-embedded sensors that can detect a fire within minutes. This means often within the initial smouldering phase, before a wildfire has a chance to get out of hand.

Dryad's Silvanet is a groundbreaking solution to the problem of wildfire detection. By harnessing the power of the sun, these sensors are able to operate continuously, ensuring round-the-clock monitoring of vulnerable areas. This technology is not only efficient but also cost-effective, making it accessible to organizations of all sizes.

The AI-embedded sensors are designed to detect even the slightest signs of a fire, enabling early intervention and preventing the spread of wildfires. By detecting fires during the initial smouldering phase, before they have a chance to escalate, Dryad's network provides a crucial window of opportunity for firefighters to respond swiftly and effectively.

graphic comparing wildfire detection speeds

In addition to its rapid detection capabilities, Dryad's network also boasts impressive accuracy. The AI algorithms constantly analyze data from the sensors, distinguishing between natural phenomena and potential fire threats. This ensures that false alarms are minimized, allowing emergency services to focus their resources where they are truly needed.

Furthermore, Dryad's system is not limited to a single point of detection. The mesh network allows for a wide coverage area, ensuring that no potential fire goes unnoticed. This comprehensive approach is particularly valuable in areas with dense vegetation or difficult terrain, where traditional detection methods may fall short.

The importance of early wildfire detection cannot be overstated. It not only saves lives but also protects homes, wildlife, and the environment. By providing a reliable and efficient solution, Dryad's network empowers communities to take proactive measures in preventing the devastating consequences of wildfires.

Dryad's solar-powered mesh network of AI-embedded sensors is a game-changer in wildfire detection. Its ability to detect fires within minutes, coupled with its accuracy and wide coverage, makes it an invaluable tool in the fight against wildfires. With this technology at our disposal, we can significantly reduce the damage caused by these natural disasters and ensure the safety of our communities.


The impact of these fires extends beyond the destruction of forests and infrastructure, reaching into the realms of public health, wildlife devastation, and climate change. As we have explored the nature of wildfires, their causes, and the challenges they present, it becomes clear that proactive measures are crucial in mitigating their devastating effects.

As we face the growing threat of wildfires, it is imperative that we embrace proactive measures and leverage technological advancements to protect our environment and ensure the safety of our communities.

By implementing early detection systems such as Dryad's network, we can take significant strides towards mitigating the risks posed by wildfires, preserving our ecosystems, and safeguarding lives and livelihoods. Together, let us stand united in the fight against wildfires and work towards a future where these destructive forces are brought under control.

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