In Defense of Prescribed Cool Burning

Prescribed burning has always been a controversial subject. The subject is going to be the epicenter of heated discussions in the days to come as the revision of management plan of Eravikulam National Park is on its way. I have always been an unabashed votary of prescribed cool burning.  The latest research buttresses my arguments.  As scientists gather more and more information on the effects of fire on forest ecosystems, they have learned that fire exclusion may not be the best practice for land management.  There is increased awareness that a forest fire is part of the overall ecology and is part of the overall balance despite earlier fears that forest fires were only deleterious. Not only does fire exclusion cause an accumulation of thick vegetation on the forest floor, but also causes and increased density of smaller trees. A fire in a forest that has been excluded from fires for many years is disastrous and pushes back all the good work by many years. The fire becomes a holocaust.  The blaze burns at a much higher intensity causing more damage to the forest ecosystem. On a long-term basis particularly in a thickly populated state like Kerala fire will be an inevitable part of forest ecosystems. So why not manage and mitigate the effects instead of living in a fool’s paradise.

Many people have concerns that prescribed fires affect animals in a negative way.  The fire itself does not harm the animals for several reasons. The prescribed burns are done in pre-designated patches. Most prescribed burns travel at a slow rate of less than 2 Km per hour giving most insects and animals time to leave the area or burrow deep into the ground.  Only 290 animals were found dead as a result of the Yellowstone fires in 1988, and this fire was uncontrollable and burned at very high intensities. Most prescribed fires occur when animals are not nesting or caring for their young. 

Forests that have not had a fire in decades may become the home to a plant species that is not adapted or dependent on fire.  Plants that are adapted for wildfire usually have a thick layer of bark to protect its living tissue from the heat.  Also, many trees are dependent on the heat of fire in order to open up their seed cones for regeneration.  Vegetation modification also affects the ecosystem’s insects and diseases, wildlife populations, soil structure, and nutrient recycling.

Recent ecological research has shown that forest fire is an integral component to the function and biodiversity of many ecological communities, and that the organisms within those communities have adapted to withstand and even exploit it. A fire may destroy one ecological community but allow greater long term diversity. It is not just the fire but the smoke also plays a very important role in the ecological processes. Smoke plays a prominent role in promoting the germination of seeds of many species following a fire. Even the carbon dioxide from a fire has an impact on the overall ecosystem.

Fire create a mosaic of different habitat patches, with sites ranging from just burned to untouched by fire for years, through a process known as succession. Succession is the progress of a site through continuous and directional phases of colonization by and extinction of species populations after a disturbance, such as fire.

In a recent study published in the Journal of Natural Products it was reported that a chemical compound in smoke from burning plants promotes seed germination. Such seeds, which remain in the undercover on forest and meadow floors after fires have been extinguished, are responsible for the surprisingly rapid regrowth of fire devastated landscapes.

In their research, the scientists report discovery of an inhibitor compound that may block the action of the stimulator, preventing germination of seeds. They suspect that the compounds may be part of a carefully crafted natural regulatory system for repopulating fire ravaged landscapes. Interaction of these and other compounds may ensure that seeds remain dormant until environmental conditions are best for germination. The inhibitor thus may delay germination of seeds until moisture and temperature are right, and then take a back seat to the germination promoter in smoke.

A recent study at Oregon State University indicates that some past approaches to calculating the impacts of forest fires have grossly overestimated the number of live trees that burn up and the amount of carbon dioxide released into the atmosphere as a result. A forest fire does not cause a complete destruction or release of carbon dioxide to the atmosphere as compared to the deliberate combustion of fossil fuels.

The past estimates of fire severity and the amounts of carbon release have often been high and probably overestimated in many cases, said Beverly Law, a professor of forest ecosystems and society at OSU. Even when a very severe fire kills almost all of the trees in a patch, the scientists said, the trees are still standing and only drop to the forest floor, decay, and release their carbon content very slowly over several decades. Grasses and shrubs quickly grow back after high-severity fires, offsetting some of the carbon release from the dead and decaying trees. Abundant tree regeneration will result in a relatively fast recovery of carbon uptake and storage.

More and more government agencies such as the National Parks Service and the USDA Forest Service are adopting prescribed fire plans. Although not all of the long term effects of prescribed fires are known, most evidence shows that a prescribed fire plan’s benefits outweigh a fire exclusion plan’s benefits.

In Eravikulam National Park prescribed cool burning has been practiced right from the British days. The ecosystem has stabilized around this practice. Tinkering with the practice is fraught with unseen dangers. In Eravikualm the recruitment of Nilgiri tahr has come down to about 5 % from the 10 to 20% that was there 30 years back. I have a sneaking doubt that tinkering with the burning regime has a role in it. Only detailed research can prove it. Other possibility is disturbance. Caughly has conclusively proved that disturbances even in the absence of  poaching bring about energetic demands on the animals affecting parturition.

Opponents of prescribed burning should read the book "Yellowstone in the Afterglow: Lessons from the Fire." Yellowstone has played a critical role in demonstrating the changes brought by fires. "The lessons of '88 in the park are like classic Led Zeppelin," says Mr. Renkin, a park ecologist. "They'll be around forever."

Have a look at the other recent papers on forest fires that are available on the net.