Understory burning is similar to broadcast burning in that it consists of low-intensity fires over large areas. Understory burns are also used to reduce fuel loads on the forest floor in order to minimize the risk of devastating canopy fires.
Longleaf pine ecosystems in the Southeastern U.S. are often prescribed understory burns. The technique creates the patches of bare soil needed for longleaf pines to reproduce, and also prevents invasive grasses from spreading.
Pile burning occurs in a concentrated area where wood and other flammable materials are stacked and burned. These fires are intended to reduce the fuel load in an area, generally after trees are selectively removed. Pile burns are prescribed in areas where large-scale fires are impractical or altogether impossible, such as national parks.
Controlled Fires vs. Wildfires
Unlike meticulously planned controlled burns, wildfires start naturally, accidentally, or by arson. According to the National Fire Protection Association, lightning strikes caused almost 25,000 fires between 2004 and 2008.
Despite often being naturally ignited, wildfires are not without significant human influence. In an area where fire has been absent, there can be a huge buildup of flammable materials, making the wildfire burn hotter and longer than if fires had never been suppressed. Under these circumstances, wildfires can quickly get out of control, devastating huge swaths of forest or grassland. From an ecological perspective, these out-of-control fires can kill large carbon-storing trees, leading to a huge loss of carbon storage.
Uncurbed wildfires also threaten people and property. In 2020, wildfires in California, Oregon, Washington, and Colorado caused an estimated $16.6 billion in property damage.
According to the Center for Climate and Energy Solutions, the climate crisis is raising the risk of dangerous wildfires by making many areas warmer and drier. These ideal fire conditions are extending the fire season in affected areas.
Fire Suppression in the US
Wildfires earned a bad reputation in the U.S. during the early 20th century. This was, in part, prompted by devastating fires that burned across Montana, Idaho, and Washington in 1910 — just five years after the founding of the U.S. Forest Service. These fires, known as the Big Blowup, burned an estimated 3 million acres of land in just two days and smoke from the fires traveled as far as New England.
These and other tragic fires led land managers, conservationists, and the public to view fires as a danger to ecosystems and people. What followed was decades of policy that favored fire suppression and dramatically changed ecosystems.