What Causes Wildfires

A wildfire is an uncontrollable and rapidly spreading fire, occurring on wildland, rangeland or brushland. It is also referred to as wildland fire, forest fire or vegetation fire. On an average, about 1.2 million acres of woodland in the United States, burn every year due to wildfires.

In ecology, wildfires are regarded as a natural process of the wildland ecosystem. However, there are both positive and negative effects of wildfires. They are considered beneficial, as many plant species depend on fire for germination and growth. On the other hand, wildfires are detrimental, as they cause air pollution and other atmospheric consequences.

The smoke from wildfires contains a mixture of gases and other particulate matter, which are harmful to health. Smoke worsens the condition of heart and lung diseases and causes irritation to the eyes and respiratory system. Many a times, wildfires destruct homes and property, situated in the zone between native ecosystems and the developed urban areas.

What Causes Wildfires

Wildfires are mainly caused due to climate change and human activities. Some of the common causes of wildfires are:

• Lightning - Wildfires caused due to lightning occur at a frequency of three to five per year. Since lightning is usually associated with rain, such wildfires do not spread over large areas.
• Human Carelessness - Majority of the cases of wildfires occur due to human carelessness, especially while handling fireworks. Debris burning and arson (burning to destroy property) are examples of other human activities that often result in wildfires.
• Slash-and-Burn Farming - This common practice of farming refers to cutting and burning of woodlands and vegetation for clearing the land. Quite often, the slash-and-burn practice results in catastrophic wildfires.
• Volcanic Activity - Sometimes, volcanoes create a favorable condition for ignition of wildfires in the nearby areas. Wildfires are also caused due to pyroclastic clouds, generated from active volcanoes.
• Underground Coal Fires - Very often, underground coal fires cause wildfires. Underground coal fires are the slow and flameless forms of combustion, below the earth's surface. Such fires continue to burn for many years, resulting in the release of toxic fumes and destruction of vegetation and human property.

Though, natural disaster and human activity cause wildfires, it is estimated that 90 percent cases of wildfires are due to human interaction with nature, either directly or indirectly.

Wildfires are more prevalent in summer and autumn. They are also common during droughts, when the fallen branches and leaves become dry and flammable. However, the overall spread of wildfires depend on weather, type of vegetation and geography and topography of the area. Under the influence of strong winds, wildfires can spread to more than 40 miles a day, which is about 1000 acres per hour.

In order to extinguish wildfires, firefighters use pulaski (combination of an axe and hoe) to dig a fireline. While constructing a fireline, the mineral soil is exposed (by removing the surface litter and organic matter), so as to stop the spread of wildfires. In case of huge wildfires, helicopters and airplanes are used for spraying water and fire-retardant chemicals to extinguish the fire.