Lake Alexander prescribed burn
Prescribed Fire. Firefighters conducting a prescribed spring burn at the Lake Alexander Preserve in central Minnesota. © Jennifer Linehan/TNC

Stories in Minnesota

Restoring Fire to Native Grasslands

Fire can be used safely to restore native grasslands and provide many benefits to people and nature.

This page was updated on September 14, 2018.

Before Europeans settled the Great Plains and upper Midwest, vast prairies and savannas once covered about 110 million acres in Minnesota, North Dakota and South Dakota, and these grasslands burned on a regular basis. Some fires were caused by lightning strikes, while many more were started by Native Americans who burned to clear the land for agriculture, improve grazing and forage for game species, direct game migration and clear brush to ease travel or prevent hostile forces from approaching unnoticed.

Fire is a natural part of the grassland ecosystem and helps maintain its health and vigor. It warms up the soil and reduces the leaf litter that accumulates each year, allowing sunlight to penetrate. Warming the soil increases microbial activity, which releases nutrients from decaying plant material that new grasses and flowers need to grow.

After a fire, blackened fields quickly revive with new, green grasses and abundant, showy wildflowers. Big bluestem, purple coneflower and blazing star are among the many species that thrive with fire. Indeed, hundreds of Minnesota, North Dakota and South Dakota’s plant species would be lost without it.

Fire Provides Many Benefits

The Nature Conservancy supports the safe and ecologically appropriate use of fire to maintain the grasslands and their plant and animal diversity in Minnesota, North Dakota and South Dakota. Here are a few of the many benefits that fire provides to people and nature:

  • Fire, sometimes in combination with cattle or bison grazing, is used to control trees, woody shrubs and invasive species and keep grasslands healthy. After a fire, grazing animals are attracted to the lush re-growth of grass and concentrate their grazing in that burned area. As new areas are burned, grazers shift to the most recent burned area, allowing previously burned areas to recover.
  • Regularly applied fire can reduce the intensity of an unplanned fire. Without fire, leaf litter builds up over time providing lots of fuel. If an unplanned fire should occur, it will be much more severe and harder to control where a lot of fuel has built up.
  • As Native Americans did before settlers arrived, land managers today use fire to maintain grasslands for wildlife including elk and other game species. Healthy grasslands provide food and cover for wildlife all year long. They can also provide nutritious forage for cattle.
  • Fire can also be used to increase wildflower diversity in grasslands, which benefits butterflies, moths and other pollinators, providing a variety of food sources throughout the growing season. Diverse grasslands also provide the different types of vegetation and structure that pollinators need during different times in their life-cycles.
  • Fire is critical to maintaining the habitat of grassland-dependent birds, including meadowlarks, dickcissels and chestnut-collared longspurs, whose populations are declining dramatically across North America and other parts of the world.

It’s Safe!

A team of highly skilled and experienced professionals and volunteers applies fire to Nature Conservancy preserves and project areas. A “burn boss” organizes and supervises the event around a written plan and schedule. Strict safety procedures ensure the safety of the team members, nearby residents and private property. Conditions such as weather, wind and drought factors must be right before a fire is lit.

See the Frequently Asked Questions below for more information about how the Conservancy uses fire as a management tool and the precautions taken to ensure safety.

Fire at Nature Conservancy Preserves

The Nature Conservancy first used fire as a management tool in the United States at Helen Allison Savanna in Minnesota in 1962. Today, the Minnesota-North Dakota-South Dakota chapter has one of the largest fire programs at the Conservancy, burning approximately 12,000 acres each year. A few of the Conservancy’s grassland preserves that depend on fire include:

  • Agassiz Dunes, Bluestem Prairie, Chippewa Prairie, Hole-in-the-Mountain Prairie, Ordway Prairie, Schaefer Prairie, Weaver Dunes and the Wallace C. Dayton Wildlife Area in Minnesota
  • Pigeon Point, John E. Williams Preserve and Cross, Davis and Brown ranches in North Dakota
  • Prairie Coteau in South Dakota

Good Fire Takes Team Work

With many government agencies and non-profits like the Conservancy working to conserve the grasslands in Minnesota, North Dakota and South Dakota with limited resources, it is important that we work together. The Conservancy works with agency partners including the National Park Service, U.S. Fish and Wildlife Service, U.S. Forest Service, Minnesota Department of Natural Resources and with private landowners to share information, provide training opportunities and implement burns collaboratively.

Fire is a valuable tool to help preserve the diversity of life on Earth – now and for future generations. Have we kindled your interest? If so, you can learn more about fire with the click of your mouse:

Frequently Asked Questions

When and how does The Nature Conservancy use fire to manage its land?

We ignite fires using carefully developed fire plans and under pre-determined weather conditions for specific resource management objectives including fuel reduction and brush control, and to reintroduce a natural disturbance to a fire-dependent forested landscape.

How are these fires conducted?

The first step is creating firebreaks—strips of cleared land to prevent fire from spreading—by removing trees, shrubs and grass using a chainsaw, mower or other equipment. The firebreaks may also be raked or disked using a tractor to remove nearly all flammable wildland fuels. Rivers and lakes are examples of natural firebreaks.

The burn unit is then ignited using drip torches—portable canisters used to drop small amounts of flammable material (usually a mixture of diesel fuel and gasoline) along a fire line. A carefully planned ignition pattern utilizes wind direction, topography and other factors to help control the spread of fire until it extinguishes itself at the firebreaks, where it runs out of fuel.

Special wildland firefighting equipment also helps control the fire and protect the fire crew – such as mobile water sources (e.g., an ATV or pick-up truck with a water tank and pump), flame-resistant clothing, specialized fire control tools (e.g., backpack pumps and a wide range of hand tools), portable pumps and hoses.

How is the fire kept under control?

Four strategies are employed in every burn to keep the fire under control:

  • Setting requirements so that the fire will only be ignited under safe, manageable conditions. These include elements such as wind speed and direction, relative humidity and estimates of fire behavior, identifying the crew and equipment needed to manage the fire, making back-up contingency plans and setting other specific guidelines for the burn.
  • Trained burn crew members continuously patrol the burn unit and its firebreaks watching for potential hazards. They use wildland firefighting equipment when needed to ensure that the fire remains within the burn unit boundaries.
  • Establishing firebreaks and a specific fire ignition pattern restricts the fire to the targeted area.
  • Emergency fire suppression equipment—including fire pump trucks—stationed at each burn can be used to quickly extinguish the fire should weather conditions change or the fire threaten to escape control.

How will this affect the ecosystem, including plants and wildlife?

Extensive research shows that fire helps cycle nutrients and reduces the invasion of less desirable fire-sensitive species such as non-native buckthorn and native cedar trees. Fire can also improve the vigor of native grasses and flowers that evolved with fire.

Because these fires are relatively small and slow-moving, most wildlife can easily escape the flames by moving to adjacent areas or by hiding in underground burrows. Some birds fly away, while others, such as hawks, may soar overhead, hunting for small prey flushed out by the fire. Some mortality of small animals may occur during fires; for this reason, land managers conscientiously burn small units at a time. Patchwork burning (i.e., burning one-quarter of a preserve in a given year) enables small animals to find refuge from fires and enables recolonization of burned areas from these refuges after the fire. It is important to realize that not burning will, in the long term, lead to loss of habitat for some wildlife species. While burning may entail short-term loss, fire managers look at habitat and wildlife management over the long term.

Fire is beneficial because it helps preserve biodiversity by maintaining habitat for species that need sunny, open conditions to germinate and thrive, such as most oaks and many wildflowers. Once the canopy is opened up by fire, it may provide an opportunity for these species by increasing the light on the forest floor.

Changes brought on by the fire can create habitat that draws an influx of new species, while other species may decline in response to the changed environment. Burned trees can provide shelter for small animals and an abundant food source for wood-boring insects such as ants, beetles and wasps. While the post-burn conditions may be less hospitable to some nesting birds, they may help others to thrive by meeting their specific habitat, food source and nesting requirements. For example, a 1995 study in California showed that nests located within a burn zone had a success rate 15% higher than in the unburned habitat. In this way, prescribed burns can help increase biodiversity by providing food and shelter for a changing variety of wildlife.

Schaefer Prairie Burn Learn why and how the Conservancy uses prescribed fire at the Schaefer Prairie Preserve in Minnesota.