Forest fires, also known as wildfires, are uncontrolled fires that occur in wooded or forested areas. They can be caused by both natural and human-related factors and can spread quickly, consuming large areas of vegetation and causing significant damage to the environment, wildlife, and human structures.

Many foresters and wildland managers have been hesitant to utilize managed fire in forest management, which is reasonable. On the other hand, fire has a place in some ecosystems’ management. The choice to employ fire is frequently based on a trade-off of advantages and drawbacks—that is, potential or predicted damage must be evaluated against potential benefits.

Purpose Of Prescribed Fire

Prescribed burning may be used to prepare seedbeds for the natural germination of most tree species, manage pest and disease infestations, minimize weed competition, reduce fire hazards, and modify forest cover type under the right conditions.

Forest animals and birds rely on wildlands for food and refuge. Fire clears dense brush from wildlands, allowing fresh grasses, herbs, and regenerated shrubs to grow in their place, providing food and habitat for a variety of animal species. The water supply is boosted when someone eliminates a dense stand of bushes. Streams are fuller as a result of fewer plants absorbing water, benefiting other sorts of plants and animals.

Prescribes forest fires also destroy many tree-killing diseases. Sometimes very useful to kill insects like borers. The fire debris also enriches the soil in the forest with important nutrients. Insect infestation and disease kill more trees each year than fire. Pitch canker and bark beetle infestations – pests that kill the portion of the tree that provides nutrients to the roots, leaves, and needles – plague many forests. Fire-charred vegetation provides a rich supply of nutrients for the trees that survive.

A healthy forest necessitates change. Some tree and plant species are genuinely fire-dependent. For regermination and to continue the life cycle, these species need fire every 3-25 years. Some trees have fire-resistant bark and cones that open and release seeds for regeneration when heated.

Different Types of Forest Fires

Forest fires can be categorized based on various factors, such as their cause, behavior, and the type of vegetation they affect. Here are some different types of forest fires:

Underground Fire

Underground fires are low-intensity flames that consume the organic stuff beneath and the surface litter of the forest floor. On top of the mineral soil, a thick layer of organic matter may be found in the densest woods. By eating such things, the fire spreads across the area. These flames typically spread completely underground and burn for many meters below ground level. This sort of fire spreads slowly, making it difficult to identify and suppress in the majority of situations. They might burn for months, destroying the soil’s vegetative cover. Muck fires are another name for this sort of fire.

Ground Fires

These forest fires start in subsurface organic fuels such as duff layers under forest stands, Arctic tundra or taiga, and swamp or bog organic soils. The boundary between subterranean and ground fires is hazy. Smoldering underground flames might turn into ground fire at any time. This fire consumes roots and other material on or under the surface, i.e., it consumes herbaceous growth on the forest floor as well as a layer of organic materials in various stages of decomposition. They are more dangerous than surface fires because they may entirely kill plants. Surface flames are more likely to start ground fires because they burn under the surface via smoldering combustion.

Surface Fire

A Forest fire may burn largely as a surface fire, spreading throughout the forest floor when surface litter (senescent leaves and twigs, dry grasses, etc.) is absorbed by the expanding flames.

Crown Fire

A crown fire is a fire that starts at the tops of trees and bushes and is typically fueled by a surface fire. Crown fires are especially harmful in coniferous forests because the resinous substance released by burning logs burns rapidly. If a fire begins downhill on a hill slope, it quickly spreads uphill since warm air next to the slope tends to travel up the slope, carrying flames with it. It’s less likely for a fire to spread downhill if it begins uphill.

Firestorms

Among Forest fires, the firestorm, which is an intense fire across a vast region, spreads the fastest. Heat increases as the fire burns, and air rushes in, causing the flames to spread. More air causes the flames to spin furiously as if they were a tornado. Flames erupt from the base of the flaming twister, and burning embers erupt from the top, igniting smaller fires all around it. Inside these storms, temperatures may exceed 2,000 degrees Fahrenheit.

Sources of Forest Fires

Forest fires are triggered by both natural and man-made sources.

1. Natural Causes – Many forest fires are started by natural causes, such as lightning striking trees and setting them ablaze. Rain, on the other hand, extinguishes such flames without inflicting significant harm. Naturally, the combination of both little humidity and high temperature creates the most ideal conditions for a fire to ignite.

2. Man-made Causes – When a source of ignition, such as a bare flame, cigarette or bidi, electric spark, or any other source of ignition, comes into contact with combustible material, it generates fire.

• Thunderstorms (but could also include volcanic meteors)
• Coal seams are a type of outcrop or underground coal seam that burns.
• Because of the tourists, there will be a campfire. Cooking, warmth, and a campfire
• Tobacco is lit using cigarettes, cigars, pipes, and matches/lighters.
• Debris burning, burning ditches, fields, or slash heaps, among other things.
• Arson and illegal or unauthorized burning are all examples of incendiary behavior.
• Vehicles, airplanes, exhaust, flat tires, dragging chains, brakes, and other equipment
• Railroads: Exhaust, brakes, and railroad work, among other things
• Juveniles: Matches, fireworks, lighters, and other fire-related activities
• Burning structures, pyrotechnics, power lines, shooting (ammo, exploding targets), spontaneous combustion (hay baled while still wet, compost piles, greasy rags), blasting, and coal seams are all examples of miscellaneous activities.

Fire Triangle

The fire triangle in forest management is a concept to understand wildfires. The triangle is also referred to as the combustion triangle. The fire triangle is a basic picture for identifying the elements required for most wildland flames. This triangle model depicts the three key ingredients that must be present in the forests for a fire to start: heat, fuel, and an oxidizing agent (usually oxygen). When all of the components are present and mixed in the proper proportions, a fire will spontaneously form. Any one of the elements in the fire triangle can be removed to prevent or extinguish a fire. Reduced oxygen levels are not normally an option in huge fires where firefighters are called in since there is no practical technique to do it across a broad region.

• Heat: A heat source is responsible for the initial ignition of a fire, as well as the maintenance and spread of the fire. Heat facilitates the spread of fire by eliminating moisture from adjacent fuel, warming the surrounding air, and preheating the fuel along its route, allowing it to travel more easily. The use of a chemical that limits the amount of heat accessible to the fire response can eliminate heat. Frequently, this is water, which takes heat to transform from water to steam.
• Fuel: Fuel is any flammable material that is defined by its moisture content, size and form, amount, and the way it is distributed throughout the terrain. The moisture level of fuel impacts how quickly it burns. Fuel can be removed naturally, such as after the fire has burned all of the burnable fuel, or manually, such as by physically or chemically removing it from the area.
• Oxygen: The oxidizer, or oxygen, is the third component of a chemical process. In most circumstances, it is made up of little more than ambient air and one of its constituents, oxygen. Most flames require at least 16% oxygen concentration to ignite, whereas air contains roughly 21% oxygen. A fire can be put out by depriving it of oxygen.

Various Factors That Effect Fire Behaviour

The method in which fuel ignites, flame develops, fire spreads, and shows other associated phenomena as dictated by the interplay of fuels, weather, and topography is defined as fire behavior.

Depending on the contributing circumstances, forest fires, the location where they occur, and the flammable substance exhibit varied behaviours. It’s crucial to understand these variances in fire behavior to develop the best methods and strategies for putting out forest fires. The capacity to efficiently and effectively deal with forest fires is contingent on accurate fire danger and fire behavior estimates. To begin, it is vital to understand the qualities of fuel as well as the climatic and topographic conditions that influence and determine fire behavior.

The forward and lateral rates of spread, flame length, height and shape, fire intensity, head fire breadth, spotting distance, fuel consumption, and fuel layers are all fire behavior parameters that are monitored during controlled or field fires.

Three key factors often influence fire behavior:

• Weather: On hot, dry, windy days, wildfire activity is more likely to increase. The more moisture the air can carry, the hotter the day grows, and the relative humidity declines. The faster the fire spreads, the stronger the wind. It accomplishes this by delivering additional oxygen to the fire and by laying over the flames, pre-heating, and drying the fuel ahead of the fire front. Spot fires can also be caused by wind carrying sparks and embers well ahead of the main fire.
• Fuels: The amount of fuel available has an impact on how fire behaves and is organized vertically and horizontally. The more fuel that can be burned, the more energy is released as heat.
• Topography: Fire travels quicker upward due to topography. A fire’s pace doubles with every 10-degree rise in slope. This is due to the slope’s comparable impact to the wind, which effectively lays the flames down into the slope and pre-heats the plant, causing it to ignite more quickly

Modern Tools in Forest Fire Control and Prevention

It is critical to provide each firefighter with the required hand tools and safety equipment, as well as a communication link and supplies for personal comfort under extremely hot circumstances.

The following is a list of the fundamental tools, instruments, and equipment supplied to active firefighters and required to handle either a controlled fire or a wildfire under control.

• Hand Tools Used by Wildland Firefighters: These hand tools used by wildland firefighters are constantly dictated by the person’s task. The amount and kind of hand tools employed are also determined by whether the fire is under control or out of control, as well as the original or anticipated size. Depending on the situation, many types of fire rakes are utilized.
• Backpack Pump and Backfire Torch: When a forest management plan advises a planned burn, a backfire torch or drip torch is a vital piece of equipment for controlling “fire with fire.” This “torch” sets fire to the inner side of the protective firebreak and the desired burn area by dripping a combination of gas and diesel fuel onto a wick. If utilized correctly, it may also shift the path of an out-of-control wildfire.
• A 5-gallon backpack water pump: adds a layer of protection from spotting embers that cross the break and burning snags and stumps close to the fire line. It is, however, extremely heavy, requires frequent refueling, and should only be handled by a physically fit fireman.
• Wearable Firefighter Protection: The following are the three most significant items that should be regarded as standard equipment for all controlled burns and wildfires. Wildland firefighting gear includes a wildland fire suit, a full-brim hard helmet, and wildland firefighting gloves.

To Conclude

It’s important to recognize that forest fires are a natural part of many ecosystems and play a role in the renewal and regeneration of certain plant species. However, the increasing frequency and severity of wildfires in some regions have raised concerns due to their impact on the environment and human communities. Managing and mitigating forest fires require a comprehensive approach that considers both natural and human factors.

Also Read: Rise in India’s Forest Tree Cover: ISFR Report