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Wisconsin Natural Resources magazine

Wisconsin Natural Resources magazine

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April 2005

Fire's role in nature

Shaping Wisconsin's landscape

Nancy Braker

Much of life on Earth has evolved with fire. Like storms and floods, fire is a powerful force that can give life or smother it. Fire has shaped many of the ecosystems we know today, in Wisconsin and worldwide.


Wisconsin's natural plant communities at the time of settlement were a mix of grasslands, oak savannas and oak forests in the south and southwest, and conifer-hardwood forests and pine savannas (or barrens) in the north. These ecosystems evolved over thousands of years under many influences. One of the most important was fire. Fire returns nutrients to the soil, exposes soil so that seeds may germinate, releases seeds from cones or hard seed covers, removes the thatch layer that shades small-statured species and plays many other ecological roles.

While lightning strikes started many fires, many more acres in North America were burned intentionally by Native Americans. Fire was used to clear the land for agriculture, improve forage for game species, direct game migration and clear brush to ease travel or prevent hostile forces from approaching.

In "The Vegetation of Wisconsin," John Curtis writes: "In the early years of settlement, the most important vegetational effects were caused by the elimination of fire." European settlers limited the extent of wildfires with their plowed fields, dirt roads and forest clearings, causing major changes in the frequency and extent of free running fire that changed the natural community.

In prairie and savanna regions of the state, land described as treeless by early settlers, quickly became covered with brush and forests as major settlements were established. Changes in fire-dependent plant communities were rapid after about 1850. Prairies, pine barrens and oak savannas disappeared as the forest canopy closed. Many of these formerly common plants and animals are now uncommon, and quite a few are listed as threatened or endangered.

Even with conservation efforts, only a small percentage of vegetation representing the original natural state remains and is largely maintained by fire such as prescribed burns.

Natural resources managers work to mimic the fire that plant communities experienced naturally. Since most significant natural fires burned when the vegetation was dry in the spring and fall, this is when managed fires usually are set. Using natural fire breaks such as rivers or lakes, or manmade breaks such as roads, mowed paths or plowed fire lines, land managers generally only burn a small portion of a protected area at one time in order to avoid damage to animal populations.

While state and federal agencies conduct most management fires, private organizations such as The Nature Conservancy, The Prairie Enthusiasts and many nature centers have prescribed burn programs as well.

For more information:

Maintaining Fire's Natural Role – The Nature Conservancy's Fire Initiative

Fire and Aviation Management – National Park Service

"Bibliography of Fire Effects and Related Literature Applicable to the Ecosystems and Species of Wisconsin," Technical Bulletin No. 187, Wisconsin DNR

"Fire In America: A Cultural History of Wildland and Rural Fire" by Stephen Pyne

Nancy Braker works for The Nature Conservancy out of its Baraboo office and is fire manager for the Conservancy's Wisconsin chapter.

Wildfire causes
About 1,500 fires annually burn over 5,000 acres on lands protected by the Wisconsin Department of Natural Resources. Over 90 percent of these fires are human-caused.

In the spring, a lack of rain and high winds can add up to especially bad fire weather. Burning debris may be left unattended and embers can re-ignite a large fire. ATV riders and other off road motorists also should be aware that grass and leaves can collect around the muffler and fall off causing a fire. If you build a campfire, clear all grass and leaves from around the area. When you put the fire out, pour water on the ashes and make a slurry to ensure that the fire is out.