Numerous swift mountain creeks carve through their rocky channels to forest and meadow below. Disturbances to the land, both natural and human-caused, influence plant and animal communities. This landscape has evolved with fire as a constant force for change and renewal. Frequent low intensity surface fires kill the small trees and shrubs and leave the more fire-resistant trees largely intact. Lodgepole pine, which maintains its seed in fire-resistant cones for several years, is often abundant on sites where whole stands have been destroyed.
Some seeds remain dormant in the soil for decades and sprout after a moderate fire.
Aspen, huckleberry, fireweed and grasses quickly move in to regenerate the vegetation. Native Americans commonly burned prairies and pine-forest understory plants to improve grazing for deer, elk and bison. Introduction of non-native species has also disrupted natural habitats, most notably fish and noxious weeds. Noxious weeds introduced largely by Euro-American settlers in crop or pasture seeds over the past two centuries, are so aggressive they have infested millions of acres, choking out native plants, and destroying fish, wildlife and livestock habitat. Landowners are responsible for eradicating weeds from their property.