The year 2019 marked 75 years of Smokey Bear, the advertising icon of the United States Forest Service who encourages visitors and campers to prevent wildfires. Wildfires are destructive forces that can result from natural causes (like lightning), human-caused accidents (like cigarettes and campfires), or deliberate acts of arson. Despite Smokey’s education campaigns, wildfires burned about four million hectares (10 million acres) of land during 2017, and in 2018, a single California wildfire, the “Camp Fire” destroyed nearly 20,000 structures and killed more than 80 people, with insured losses topping $10 billion. However, while these frightening and negative consequences dominate news headlines, forest fires have a positive side. Controlled use of wildland fires for positive environmental effects is common around the world.
While a wildfire refers to an unintentional, uncontrolled fire, the term “wildland fire” is broader and includes fires purposefully set as part of prescribed burns. While all fires have the potential to become dangerous to property and life, prescribed, or controlled, burns are planned extensively and performed with tight safety parameters. Humans have been performing such burns for thousands of years and for multiple reasons, but, today, they are mainly used to promote ecological health and prevent larger, more damaging, uncontrolled fires.
It might seem counterintuitive that a fire, which burns plant life and endangers animals within an ecosystem, could promote ecological health. But fire is a natural phenomenon, and nature has evolved with its presence. Many ecosystems benefit from periodic fires, because they clear out dead organic material—and some plant and animal populations require the benefits fire brings to survive and reproduce.
For example, as dead or decaying plants begin to build up on the ground, they may prevent organisms within the soil from accessing nutrients or block animals on the land from accessing the soil. This coating of dead organic matter can also choke outgrowth of smaller or new plants. When humans perform a prescribed burn, the goal is to remove that layer of decay in a controlled manner, allowing the other, healthy parts of the ecosystem to thrive. Moreover, nutrients released from the burned material, which includes dead plants and animals, return more quickly into the soil than if they had slowly decayed over time. In this way, fire increases soil fertility—a benefit that has been exploited by farmers for centuries.
Several plants actually require fire to move along their life cycles. For example, seeds from many pine tree species are enclosed in pine cones that are covered in pitch, which must be melted by fire for the seeds to be released. Other trees, plants, and flowers, like certain types of lilies, also require fire for seed germination.
Even some animals depend on fire. The sole food source for the endangered Karner blue butterfly caterpillar (Lycaeides melissa samuelis) is a plant called wild lupine (Lupine perennis). Wild lupine requires fire to maintain an ecosystem balance in which it can thrive. Without fire, the lupines do not flourish, and the caterpillars cannot consume enough food to undergo metamorphosis and become butterflies. In this way, healthier, post-burn plant populations generally have broad food web effects that trickle up to the foragers and other animals in the ecosystem. Similarly, animals that use pine trees for their homes benefit from the germinating powers of fire.
Perhaps surprisingly, the animal casualties from wildfires are low—animals survive by burrowing into the ground or fleeing to safer areas. Conversely, fires can help rid an ecosystem of invasive species that have not adapted to regular wildland fires. While animals and plants within fire-prone ecosystems have adapted to thrive within a cycle of wildfires, invasive plants and animals are less likely to recover and could thus be controlled or even eradicated from the ecosystem they invaded.
Moreover, prescribed burns are well established as a way to prevent more devastating naturally occurring fires. The buildup of decaying organic matter on the ground is fuel for wildfires. Without periodic fire to clear this out, a naturally occurring fire may grow and move quickly, doing much more damage that a prescribed burn—and without its safety parameters.
In the end, it is true that the burden of preventing uncontrolled wildfires lies with humanity. Smokey Bear’s message is right—nearly 85 percent of wildfires originate from human activity, and we have to take action to prevent these damaging fires. But suppression is not enough. Nature needs fire, and ecologically benefits from periodic burning. In fact, suppression alone might make matters worse, depriving nature of its equivalent of spring cleaning and leading to hotter, larger blazes when built-up forest decay finally catches flame. Understanding and appreciating the benefits of fire is the only way to truly keep our homes, population, and ecosystem safe from its dangers.