Fire is an important part of Idaho’s ecosystems. It serves as a cleansing agent for both forests and rangelands.
More than 50 percent of Idaho is forested. Over time, forests grow thick with living and dead vegetation. Some wildfires burn all vegetation in a forest, but many leave behind a mosaic of live and dead plants.
After a wildfire, new vegetation has room to grow. New trees and tender grasses sprout in the sunlight, attracting wildlife such as elk, deer, and antelope.
Some trees rely on wildfire to repopulate the forest. Several species of native conifers are serotinous—the seeds remain in resin-covered cones, often for many years, until they are exposed to intense heat. The heat melts the covering and allows the cones to open. The seeds then fall to the ground just when conditions for germination are optimal—in the ashes immediately after a fire.
About 45 percent of Idaho is covered in rangeland. Rangeland can be a prairie, plain, savanna, steppe, or grassland. Rangeland vegetation consists of grasses, broadleaf plants (forbs), and shrubs that can survive on little moisture, especially during the summer.
Idaho rangelands produce a wide variety of goods and services, including wildlife habitat, livestock forage, water, mineral resources, wood products, recreation, open space, and natural beauty.
As in forests, wildfire plays an important role in the health of rangelands. Without regular wildfires, juniper trees begin to grow, crowding out sagebrush and grasses and reducing habitat for sagebrush-dependent wildlife such as sage grouse.
Good Fire/Bad Fire
Not all wildfires are good for Idaho ecosystems. In recent years, Idaho has experienced several large, long-lasting wildfires, which burned thousands of acres at a time. It is safe to say that these large burns are “bad fires.”
Wildlife is often affected by large burns. For example, animals such as deer, elk, rabbits, and chipmunks, sometimes must find new areas to forage for food.
Rangeland fires can also create opportunities for noxious weeds. Cheatgrass is an example that is widely distributed throughout the western U.S. An introduced species, cheatgrass has spread rapidly throughout Idaho, negatively affecting native rangeland plants such as sagebrush, grasses, and forbs. Cheatgrass sprouts earlier in the spring than native grasses, depriving them of soil nutrients and water. It is also very flammable and grows as a continuous bed, unlike Idaho’s native grasses, which grow in clumps. For this reason, wildfire burns rapidly through cheatgrass, creating larger, faster-moving wildfires that are difficult to control.
For more information on noxious or invasive weeds, visit the Bureau of Land Management/Idaho Department of Agriculture Noxious Weed website.
Go to Wildfire Ignition, Behavior, and Effects to learn more about how a wildfire starts, how wildland/urban interface homes ignite, and wildfire behavior and effects.