[Explainer] The good, the bad, and the ugly side of forest fires

Forest fires, also called wildfires and bush or vegetation fires, are described as uncontrolled, often widespread burning of plants in forests, grasslands, brushland, and tundra.

These fires can be of three types – surface fires, ground fires, and crown fires. Surface fires are the easiest fires to control and cause the least damage as they burn only surface plant litter. Ground fires, also called underground or subsurface fires, burn within humus, peat, and piles of vegetation that are dry enough to burn. Although such fires spread very slowly, they are often difficult to suppress or fully extinguish, which makes them dangerous. Crown fires are the most intense and dangerous forest fires as they burn whole trees and can spread rapidly by spreading across tree tops due to winds.

The 2022 report on wildfires by the United Nations Environment Programme (UNEP) notes that although human carelessness and lightning strikes may start wildfires, climate change, land-use change, and poor forest management are allowing these fires to burn longer and hotter than ever before. The report also provides a new classification for forest fires – landscape fires and wildfires. Landscape fires are defined as being seasonal, of moderate intensity (with few instances of high intensity), easily controlled, and having a low environmental impact (for some species it may even have a positive impact). Wildfires are defined as extreme events, of high intensity, that are difficult to control, and have severe social, economic, and environmental impacts.

How are forest fires started?  

According to the 2020 report by the World Wildlife Fund (WWF), humans are responsible for 75% of all forest fires. Naturally occurring forest fires can be caused by lightning, volcanic activity, and coal seam fires, though these are relatively rare.

Typically, human negligence – often in the form of a carelessly thrown matchstick or cigarette, or a smoldering campfire left unattended – can start an uncontrolled blaze, though in many cases active arson is also suspected. In India, more than 95% of all forest fires are caused by humans either unknowingly, or through negligence.

The behaviour of a forest fire typically depends on three factors – fuel (vegetation amount, structure, continuity, and dryness), weather (air temperature, relative humidity, solar radiation, rainfall, and wind speed/direction), and land topography (slope, aspect, and elevation). All of these conditions affect how soon the forest fire is spotted, its intensity, spread rate, flame height, and duration. Large amounts of dry fuel and low relative humidity coupled with high winds can fan the flames of relatively small fires into blazing infernos that can eat up acres of forest land.

How can forest fires be controlled?

Technology has very limited utility in fighting forest fires, but is most useful in detecting fires at an initial stage and can even be used to anticipate fire occurrence on a given day. This is because forest fire behaviour is highly dependent on prevailing local factors such as weather, fuel availability, and the lay of the land. Therefore, a thorough understanding of these factors and appropriate preparations during fire-risk seasons are the best strategies for tackling forest fires.

In addition, strengthening fire-watch and rapid response systems to fires, specially by empowering local communities, can help in better management of forest fires. Active measures at fire suppression in the Nilgiri Biosphere reserve seem to have paid off as the overall frequencies of fires and area burnt had steadily decreased between 1989 and 2014.

The risk of forest fires can also be reduced by judicious management of fuel availability in fire-prone areas by pre-emptively burning vegetation in strategic spots to create ‘fire-breaks’. While setting fires to control fires sounds counterintuitive, controlled fires have been found to be very useful in both, forest fire prevention, as well as forest land management.

Why are some forest fires good?

According to Bharath Sundaram, an assistant professor of environmental studies at Krea University, India has different types of forests, each of which respond to fire differently.

In his commentary on alternate perspectives on forest fires, he points out that dry deciduous forests (the North Deccan forests in east-central India) and savannahs (such as the grassy ‘forests’ of Bandipur) have evolved with the regular occurrence of fires over millions of years. “The iconic shola-grassland system is maintained by frost and fire, with frost creating tree stunting and grass die-back, and fire preventing ingress of the vegetation when occurring on the grassland,” he writes. However, other systems such as evergreen forests (such as those in the Western Ghats, northeast India, and Himalayan foothills) have not been regularly exposed to or evolved resistance to forest fires and so these forests cannot withstand even low-intensity fires.

Despite the danger that fires pose to forests, all forest fires may not be bad fires. Indigenous people like the Soligas and Kurubas have used controlled forest fires in landscape management. The ground fires lit by these communities kept down hemiparasite populations and probably reduced incidences of tick-borne diseases, while also stimulating the growth of grasses that served as fodder.

The tribes’ selective firing stimulated grass growth and curtailed tree growth, which helped these people to maintain their pasturelands. This not only ensured better visibility and safer movement for collecting non-timber forest products, but the fire-stimulated grass growth also inadvertently supported local wild herbivores.

However, since the complete ban on fires that was brought in during the British Raj, local communities have suggested that hemiparasites are now overwhelming larger trees. Furthermore, the invasive Lantana has spread through forests causing widespread loss of native understorey plants and changes in forest structures. The massive fire in Bandipur late in February 2019, which destroyed over 60 square kilometers of forested area, is thought to have occurred due to a poor understanding of how fires provide ecosystem services.

The total ban on forest fires precluded the occurrence of grass or ‘cool’ fires that usually burn fast at much lower temperatures. Draconian fire suppression policies coupled with the invasive spread of Lantana in this landscape contributed to a massive buildup of fuel which created a huge conflagration that killed off whole trees.

Why are some forest fires bad?

Forest fires can have lasting negative impacts on biodiversity and are especially dangerous in evergreen forests such as those along the Himalayan slopes which are also home to rare flora and fauna.

In addition, forest fires directly impact the economic stability of many communities that live in forests and depend on non-timber forest products as a source of income. By the end of May 2021, the Indian Forest Department had sent out more than 3 lakh fire alerts, a number that was nearly triple that of the previous year. Forest dwellers, already reeling under the economic impacts of the COVID-19 lockdown, were hit hard.

Added to the loss of income, was the terrifying threat of having their homes burnt as many of the fires this year were more massive and burning hotter than ever before. During the peak fire season (November–June) in 2020–2021, there were more than 21,000 large forest fires, of which over 1500 burned for four days or more; of these, 24 lasted 10 days, and two blazed on for two weeks. This year, the Forest Survey of India (FSI) spotted over 7800 fires in just 3 days towards the end of April.

At a time when the world is looking for solutions to bring down atmospheric carbon dioxide levels by locking it into forests, grasslands, soils, and other areas, fires – especially large forest fires – are reversing these efforts. The forest fires from Uttarakhand in just one month alone (March) in 2021, emitted nearly 0.2 mega tonnes of carbon.

Globally, forest fires were responsible for emitting about 1.76 PgC (Petagrams or 10¹⁵ grams of carbon), which is about 5% of the total emissions of about 36 PgC. In an effort to curb these emissions, the practice of harvesting large-diameter timber trees was introduced (to ‘reduce’ fuel loads in forests), but recent work shows that this practice may actually do more harm than good. Harvesting such trees leads to higher carbon emissions than if forest fires had actually occurred. Instances such as these highlight the need for a better understanding of forest ecosystems to create effective policies that reduce the negative impacts of forest fires without resorting to extreme measures to suppress them.

Given that 36% of India’s forests are prone to frequent forest fires, with nearly 4% being extremely prone to such fires, India needs comprehensive forest fire mitigation strategies. While there have been setbacks to such efforts, India is working towards improving its forest fire fighting capabilities. The FSI is using satellite imaging technology to set up fire alert systems and analyse fire-affected forest areas to better understand the ecology of forest fires for restoration and fire prevention efforts.

Banner image: Fire at the Bandipur National Park in 2019. Photo by Naveen N Kadalaveni/Wikimedia Commons.