Fire in Yosemite has many faces. It is a force that some people are fearful of, and others are inspired by. It is a phenomenon that is both fascinating and dangerous. In Yosemite, it is something that the park's staff manages carefully and continue to learn about. (See 2004 Fire Management Plan and the 2009 Operational Fire Management Plan.)
Yosemite's has an extensive fire history, including its prescribed burn history. Historically, fire was often seen as a negative force, but in recent years it has been realized that the benefits of fire in forests are numerous.
Yosemite's fire management program is designed to protect life, property, and natural and cultural resources, while ensuring the continuation of fire as a natural process. Yosemite's fire managers recognize that fire has been an essential part of the ecosystem for thousands of years. Due to decades of fire suppression, the natural occurrence of fire was eliminated, resulting in overgrown and unhealthy forests.
Naturally occurring fires allow forests to be thinned, opening the canopy and allowing sunlight through. Fire also allows for the recycling of nutrients to the soil while reducing the amount of dead, woody debris. This allows for the sprouting and regrowth of plants, shrubs and trees. A large accumulation of combustible material on the forest floor is hazardous and threatens to destroy forests and structures in an unwanted fire.
Fire managers use three tools to mimic fire's natural function in the ecosystem: prescribed fire, mechanical thinning, and wildland fire use. While visiting Yosemite, you may see evidence of any of these practices.
Prescribed fires are ignited by qualified park fire staff under certain pre-determined conditions. These fires are carefully managed to achieve such goals as public safety (by protecting developed areas) and ecosystem restoration (by clearing unsafe accumulation of dead and down wood).
Mechanical thinning removes smaller trees and brush with tools such as chainsaws. You may see piles of cut material while visiting Yosemite. Mechanical thinning helps provide community protection from unwanted wildland fire and provides safer conditions for firefighters.
Wildland fire use fires are caused by lightning and burn naturally in certain park wilderness areas under specific conditions, and with close surveillance by park fire staff. These fires are managed and allowed to burn to fulfill their natural role as an agent for the ecosystem. Where it is not prudent to allow fires to burn, park fire staff will suppress them.
"...we can't cut our way out of the problem. We can't burn our way out. We can't simply suppress. And we can't walk away. But maybe, we can cut a little, burn a little, suppress a little, and sometimes just back off from a fire that we can't hope to stop. The process will take decades, not years, but taken together, a lot of small steps could make a big difference." -- Author Stephen J. Pyne