Prairies, wetlands and woodlands burned with some frequency. As this area became more densely settled, fires were extinguished before they spread, disrupting the natural disturbance patterns. 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 the spread of plants that are adapted to fire, Djupstrom explained, while simultaneously killing off many of the woody and weed plants that would otherwise have taken over the sites. Fire enriches the soil and lengthens the growing season.
Fire also allows diverse, native plant and animal communities to thrive.
Although burning bans may be in place in several counties, the DNR crews are often exempt because trained crews and specialized equipment are used to conduct these burns to ensure that the process is done carefully. Local fire departments are notified in advance of a burn. Before a burn begins, wind speed and direction, temperature, relative humidity and fuel conditions are calculated. The burn leader also takes into account smoke drift, nearby buildings, livestock and other safety factors. Other agencies and organizations also burn prairies.