posted on May 18, 2005 00:00
Controlled fires help restore, protect Minnesota's prairies (2005-04-19)
Controlled burns will be conducted on the prairies and savannas of western, central and southern Minnesota this spring. Unlike wildfires, these fires are part of a carefully managed prairie/savanna conservation program to make these grasslands better for wildlife and native plants.
The fires are part of the Minnesota Department of Natural Resources (DNR) Prairie Conservation Management Program. Only a portion of native grassland at any given location is burned at one time, which creates a mosaic of habitat conditions and leaves refuges from the fire for plants and animals.
Many natural communities are vitally linked to fire. Historically, fire was a common feature of the midwest landscape. Prairies, wetlands and woodlands burned frequently. As the area became more densely settled, fires were extinguished before they spread, disrupting the natural disturbance patterns. With the cessation of fire, society has allowed many fire intolerant, non native species to out-compete native, fire adapted plants, according to Ellen Fuge, DNR Scientific and Natural Areas Management supervisor.
"Intact prairies, wetlands and woodlands are species rich," Fuge said. "With the heavy competition from non native species, these areas have a tendency to become thickets of shrubs or weeds, with very little diversity. By reintroducing fire, we're reintroducing a natural process."
Fire controls the invasion of undesirable plants by stimulating the spread of plants that are adapted to fire, Fuge 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 restrictions are in place in several counties, DNR crews are often granted variances because trained crews conduct these burns using specialized equipment.
"Prescribed fires" set by DNR burn teams are controlled from beginning to end. Local fire departments are notified in advance. Before a burn begins, temperature, wind speed and direction, relative humidity and fuel conditions are calculated. The burn leader takes into account smoke drift, nearby buildings, livestock and other safety factors. A burn is conducted only if the conditions meet the approved "prescription" for the project, since prescribed burns have a set of definite vegetation objectives.
The Nature Conservancy and U.S. Fish and Wildlife Service also have burning programs.
Prairies are Minnesota's most endangered natural habitat, with less than one half percent left of the state's original 18 million acres of prairie.
"Prairies once stretched from the southeast across one third of the state to the northwest," Fuge said. "Prescribed fires help us keep healthy the little bit of prairie we have left."