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Roadside Use of Native Plants

Implementing Prescribed Burns: Burn Management — as a Roadside Tool

Wayne R. Pauly, Dane County Parks, Wisconsin

There is no substitute for fire in managing some natural plant communities. Here in Wisconsin, grassland fires favor prairie plants and discourage unwanted weeds, while woodland fires favor oaks and discourage most other trees and brush including buckthorn and honeysuckle. Fire stimulates blooming, seed production, and the general health of prairie remnants. However fire does little to discourage "weeds" in most ordinary roadside mixes.

Fire management requires as little as a few hundred dollars in equipment including drip torches, 5-gallon water back packs, flappers, rakes, and safety clothing. Of course several hundred gallons of water with a high pressure pump and hose are also handy to have.

Roadside prescribed burns are fairly easy. The road is one fire break and the others can be a mowed strip, a plowed field, harvested hay, or lawns. Some lessons, though, are learned the hard way. For example, corn stubble burns quite well, old fence posts smolder while newer ones usually don't, and a crack in a wooden telephone pole acts like a chimney conducting the fire to the top.

Common sense and planning, along with lawn mowers and rakes, solve many problems. However, the quickest and safest way to learn fire behavior is the prescribed burn classes sponsored by local conservation organizations or state natural resource staff. Form partnerships with private and governmental conservation organizations and have their fire bosses work with your crews. Solicit help from local volunteer fire departments who want to learn about prescribed burns, since most of their available formal training involves structural fires, or attacking wildfires.

Many highway departments have staff who've had personal experience burning, especially in rural areas where farmers burn out fence rows, roadsides, and drainage areas to keep down weeds and 'clean up' areas. With training, road crews can easily handle the hazards of prescribed burning just as they handle the every day risks of roadside work.

The most frequently overlooked factor affecting a grass fire is relative humidity. On an early morning with a 95% humidity grass won't burn, but a few hours later a rising temperature might reduce it to 60% allowing a nice slow fire. Finally, by late afternoon on a warm, sunny, spring day a 25% humidity would encourage a hot, lively grass fire. Below 15% fire conditions are usually too hot to handle. A frequently used rule of thumb is that a temperature rise of 20 degrees will reduce relative humidity by one-half.

Fire is a powerful tool for improving some native plant communities, but as with all powerful tools, it can cause problems. You should seek training and respect fire as a necessary but untamed force of nature.

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Questions and feedback should be directed to Deirdre Remley (deirdre.remley@dot.gov, 202-366-0524).

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