Benefits of Prescribed Burns

By Ari Zimney

Many years ago, much of Sauk County consisted of oak savanna, a fire-adapted ecosystem. This habitat is distinguished by interspersed oak trees, predominately bur or white oak, surrounded by a distinct understory of grasses and forbs. Such understory residents include little bluestem, black-eyed Susan, and common milkweed. Regular fires on the landscape help maintain the spacing of these oak trees and reduce fuel loads in the area by burning through duff, a layer of partially decayed organic material. Removing the duff layer not only lessens the threat of wildfires but promotes vegetation regrowth and adds nutrients to the soil.  

For years, Indigenous peoples of Wisconsin and beyond have utilized the power of fire as a means of boosting forest health. Before Europeans settlers arrived, these original caretakers of the land utilized fire as a means of land management, controlling invasive species, and clearing sightlines for hunting purposes. Europeans suppressed fire, which allowed woody shrubs and trees to establish themselves and shade out the once open savannas, drastically altering the habitat function and vegetation structure.

And if prescribed fires didn’t promote enough benefits, they also assist in maintaining ecosystem functionality for many species that rely on the open savanna and interspersed oak tree structure. Species such as the Red-headed Woodpecker, Blue-winged Warbler, Willow Flycatcher, Field Sparrow, and American Woodcock are all species that need oak savannas to not only live but thrive.  

Here at the Aldo Leopold Foundation, prescribed burns are a management tool rather than a method of destruction. Looking at the land history (when the last burn was, what the ecosystem is like, etc.) is the key first step in deciding if a prescribed burn will occur or not. If there is a lot of woody underbrush or invasive species that need managing, it can be added to the prescribed burn “hopefuls” list, a site we hope to burn when conditions are right. Our objectives can shift a little from burn site to burn site, but typically include promoting grassland and prairie, opening woody understory, managing invasives, expelling nutrients into the soil, and releasing latent seedbanks. In alternative situations, each of these individual objectives could take many hours of work and resources on their own, but with fire, many different objectives can be accomplished in one go.

When looking at environmental factors that play into conducting prescribed burns, many different elements need to work in our favor. Wind direction, dew point, relative humidity (RH), cloud cover, temperature, fuel load, acreage to be burned, and days since last rain are considered. When conditions are right, burning is a comparatively low effort land management technique with extremely high returns. A crew of 4-12 people can conduct a burn over dozens or even hundreds of acres over the course of a day removing woody underbrush that may take the same crew weeks to clear by hand, without the added benefits of nutrient cycling. Once a site is selected, and long before the burn evolves into an “all hands-on deck” event, other preparatory work needs to have taken place. Our land stewardship fellows, Lily, Sophie, and Cate, along with ALF staff, have been doing great work to get our expected burn sites ready!  

Creating burn breaks is the biggest priority. A burn break is a perimeter around the desired burn site that has no vegetation, often bare mineral soil, that act as a stopping point for the burn. The burn breaks keep fire contained inside the unit, and largely minimize threats of fire escaping―jumping out of the unit and into other, undesirable areas. Mowing down, weed whacking, raking, and leaf blowing vegetation along the burn break creates an obvious perimeter for staff working the fire, but also decreases the risk of fire traveling where it isn’t supposed to go.

Felling trees along the burn break is crucial to minimizing hazards of fire “climbing and jumping” the burn break. Stump grinding along the burn break is also extremely useful to make paths drivable and ensure work vehicles and UTVs are not damaged during the burn. Clearing large, dense fuels such as big sticks, stumps, and woody debris along the break and moving them further inside the unit also minimizes risk of fire getting out of control near the burn break. When there are “priority trees” we want to protect from fire inside the burn area, a circle will be mowed around it to act as a buffer. Creating shorter vegetation around the tree correlates to shorter flame height, protecting the tree from nearby flames.  

We will also ensure our tools are up to our safety standards as well. Drip torches (used to start the fire and spread it) are filled, rogue tools (metal rakes, stiff-bristle brooms, water tanks, and firefighting pumps) are piled in the truck, AED, loggers first aid kit, eyewash and burn salve is loaded into a First-Aid Backpack, and Nomex clothing (able to withstand intense heat) are fitted.

On the day of the burn, the burn team will drive or walk, the perimeter of the burn unit to double check the quality of the burn break. If there are spots we’d like to see more brush removed, or a big log near the edge of the unit, we will move it or trim it down until it is no longer a hazard. Once ready, a test fire occurs at the point of ignition (POI) designated in the burn plan. We will start a small fire, watch how it moves with the wind, and see how quickly the vegetation is catching, and reassess if the fire doesn’t behave how we’d expected. Before the burn is officially underway, all crew members will be asked “are you comfortable?”―comfortable with the conditions, burn plan, and roles during the burn. Everyone has the chance to decide if they are comfortable or not, with plenty of support if rework needs to take place. Once everyone is comfortable, the burn will commence!

So much learning takes place on site at burn breaks, and so much camaraderie too! Fellows are learning how to communicate effectively, efficiently, and understand the important roles each person plays at the burn site, and I look forward to sharing those moments in the future!

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