Fire prevents brush and trees from overtaking the prairie, prevents build-up of dead vegetation that encourages weeds and retards new growth, and improves habitat for prairie birds, mammals and butterflies, many of them endangered. Intact prairies, wetlands and woodlands are species-rich. With the heavy competition from nonnative species, these areas have a tendency to become thickets of shrubs or weeds, with very little diversity. Fire controls the invasion of undesirable plants by stimulating those plants that are adapted to fire to spread, while simultaneously killing off many of the woody and weed plants that would have otherwise taken over the sites.
Fire enriches the soil and lengthens the growing season.
Fire allows diverse, native plant and animal communities to thrive. In general, prairies thrive by occasional influence of grazing and fire. One way managers decrease the risk is by constructing a barrier around the prescribed burn site. Natural firebreaks such as roads, ditches, water or other physical features devoid of natural fuel are the best barriers. Most often, however, a firebreak must be built ahead of time to burn away materials that would fuel a wildfire.