Controlled (Prescribed) Burns

One of the most important management tools in restoration ecology is fire.

Fire is a natural element in the ecosystem, and under appropriate conditions may develop spontaneously as a result of lightning strikes. Lightning-caused fires occur mainly during warm windy dry conditions and hence occur rather randomly. However, tree ring studies have shown that most oak savannas were burned at 10-year or more intervals.

Imitating nature, humans throughout the world have used fire for thousands of years. In North America, fire was used by Native Americans to encourage berry production, expose acorns for collection, prepare planting sites, control undesirable pests, fireproof villages, create and maintain open woodlands and savannas, concentrate game, and help maintain trails. Fires were ignited either in spring, before plants had started to grow, or in fall, after frosts had killed above ground parts of plants.

When European settlers displaced Native Americans, the use of fire continued, for many of the same reasons. In the hill country of southwestern Wisconsin, farmers continued to use fire to keep grazing land from getting choked with brush and weeds. Early spring burns encourage the growth of grasses by removing detritus and debris, and by top-killing shrubs.

However, by the late 19th century, widespread logging left vast acreages with dried slash that ignited easily and burned with unusual power, creating landscapes prone to dangerous high-intensity wildfires. State laws related to wildfires were enacted to prevent damage to the land and to humans. In the early 1900s, the newly established U.S. Forest Service began a major campaign to control forest fires. "Smoky the Bear" was created as an icon of fire suppression. All of these activities had unintended consequences, destroying the values that the oak forest provided, and replacing the oaks with undesirable trees and shrubs.

Fire was reintroduced into the Upper Midwest as a management tool in the 1940s by John Curtis and associates during their work on the establishment of new prairies at the University of Wisconsin-Madison Arboretum. The demonstration of fire’s utility led to a gradual increase in the use of fire throughout the region.

Prescribed Fire

The term "prescribed fire" refers to fires that are set on purpose according to a written and approved plan, the prescription. The plan describes the objectives of the burn and the expected results. The burn plan specifies, either in words or by a map, the parcel of land to be burned, the landowner(s), and owners of adjacent land not included in the burn. Any considerations of smoke management are identified. The burn plan specifies the required governmental permits, and lists those who must be notified on the day the burn is to take place. The locations and characteristics of all fire breaks are given, as well as strategies for containment of fire within the burn unit. Any preparations of the burn unit needed before the burn can take place are indicated, including a list of fire sensitive elements within or near the burn unit that must be protected. The burn plan should state the personnel needed, as well as their qualifications and duties. The burn plan also lists the equipment needed to conduct the burn.

In Wisconsin, prescribed fire is now a critical management tool for organizations such as The Nature Conservancy, The Prairie Enthusiasts, Pheasants Forever, and the Wisconsin Department of Natural Resources. Many private landowners also use prescribed fire on a regular basis. The U.S. Department of Agriculture, through its Natural Resources and Conservation Service, strongly promotes the use of prescribed fire in management of private lands that have been dedicated to various soil and water conservation programs. The Wisconsin Prescribed Fire Council strives to make the use of fire in Wisconsin safer and more accepted. A number of commercial contractors carry out prescribed burns for landowners.

Since the early 1970s there has been a gradual reintroduction of the use of prescribed fire. Even the forest industry now realizes that in the oak forest fire plays a major role in removing many weedy trees and shrubs. Prescribed fire removes the thin-barked shrubs and trees from the midstory and understory of the forest without harming the dominant oaks. Fire also consumes the litter, thus promoting the growth of grasses and forbs, and encouraging the regeneration of oak. Long-term research studies have shown that annual burns over a number of years gradually restore the oak savanna to its original state.

 
Prescribed burn in bur oak savanna. Note how the fire hugs the ground. The principal fuel is oak leaves. Prescribed burn in prairie. The principal fuel is Indian grass.
 

History of Fire Use at Pleasant Valley Conservancy

According to oral reports, the farmers who had settled the Pleasant Valley Conservany area (the Lockwoods) had used fire every year to encourage early "green up" of the grazing land. The south-facing slope as well as the white oak savannas surrounding the Pocket Prairie were burned. After Harold Lockwood died in the 1950s, the land fell into absentee ownership and fire was no longer carried out.

We introduced fire to Pleasant Valley Conservancy soon after restoration work began in 1997. Originally only small burns were carried out, on areas that had been newly restored. These were primarily prairie remnants on the south-facing slope. As restoration advanced, more areas were burned.

The results were dramatic. The south-facing slope that had originally been heavily brushed in was opened up, prairie grasses flourished, and many prairie forbs appeared. Beginning with two small prairie remnants of about 0.5 acre each (Units 1 and 4), the whole south slope eventually was restored and burned. In recent years, south slope burns of 25-30 acres have occurred.

Prescribed burn of the south-facing slope carried out in March 2003, after 5 years of restoration work. The principal fuel is little bluestem and Indian grass.

 

Starting in 1998, annual savanna burns have also been carried out (see left photo above). These burns have proceeded in tandem with control of brush and weedy trees. In recent years, 50 or more acres of oak savanna have been burned, in either the fall or spring burn season.

Burns have also been carried out on the north-facing oak woodlands. The first burn was done in the fall of 1999 and was very successful. The north woods was burned again in the spring of 2007. Because of its aspect, it takes much longer for the north woods to dry out sufficiently so that it can be burned, and only in certain years can it be burned.
Lady slipper orchid (Cypripedium caleolus) growing out of the ashes of the fall burn of the north woods. A large number of these orchids developed after the burn, noticeably more than usually develop.

 

Each year we prepare a map of areas that were burned. The one for the 2007-2008 burn season is shown below.

 

 

The Burn Permitting System

Burn permits are required in our part of Wisconsin between January 1 and May 31. The rest of the year we can burn without a permit, although we must notify the local fire department (Black Earth Joint Fire District) that we will be burning. Therefore, we can carry out fall burns without a permit, but need one for spring burns. Our permits are issued by the Fire Control Ranger of the Division of Forestry of the Wisconsin Department of Natural Resources. Most of our burns are carried out between the middle of March and the end of April. (These permits are for daytime burns. Burns carried out after 6 PM can be done with a permit issued by the local fire warden.)

Every February we submit to the Ranger our spring burn plan. Based on this plan, our permits are issued, one for each burn in our plan. However, we must obtain oral authorization from the Ranger on the day of the burn. We reach the Ranger through the District Office in Dodgeville. Once we have authorization, we can proceed with the burn.

Procedures for carrying out prescribed burns, and details of the permitting system, can be found in a publication of the Wisconsin DNR titled "Prescribed Fire Management (Part II of Chapter 17 of Wisconsin Forest Management Guidelines" (Pub-FR-226-2003). Download a PDF version. Note that although the prescribed burn program is administered through the Division of Forestry, it does not include only forests. Prairie and wetland burns are also regulated by the Forest Ranger.

 

Burn Equipment Used at Pleasant Valley Conservancy

We are well equipped to carry out safe and effective prescribed burns.

Water Our electrically operated well provides an unlimited amount of water.

Pumper Units We have two pumper units available.

  • Kawasaki Mule (4 WD All Terrain Vehicle) with 65 gallon tank, 100 feet of hose, high-pressure hose nozzle, 5.5 HP Honda gasoline operated engine. An additional 200-feet of hose can be added if needed.
  • Custom designed high pressure pumper unit installed in a full-size pickup truck. 100 gallon tank, 300 feet of hose, high-pressure hose nozzle, 6 HP Tecumseh gasoline operated engine. Although less mobile than the ATV, it can carry more water and the long hose can reach fairly remote areas. Here the unit is being used to put out fire in a living but hollow bur oak which caught fire during a savanna burn. The truck is owned by Savanna Oak Foundation but the pumper unit, designed by Tom Wise, is shared equipment of The Prairie Enthusiasts.

Backpack Water Sprayers We have five backpack water sprayers with special waste-band harnesses. This 5-gallon unit has a brass slide-action hand-operated pump. It is possible to spray precisely and accurately. This sort of unit is used for putting out small (spot) fires or for controlling fires in areas inaccessible to ATVs or trucks.

Flappers We have two flappers for use in putting out small spot fires.

Drip torches We have three drip torches capable of dispensing fire (lighted fuel) along a fire line or throughout a burn unit. The tank is a heavy-duty aluminum canister with a specially designed fire nozzle equipped with a safety loop that prevents flashback. A check valve in the cover provides a second level of protection against flashback. The fuel is a mixture of 2 parts diesel and 1 part gasoline. Once lighted, the fire drips slowly out of the end.

Two-way radios We have four wide range two-way radios, each capable of reaching anywhere in the Conservancy. Our radios are Kenwoods that are capable of transmitting up to 6 miles, even over rough terrain and through smoke. They are pretuned to channels used by the Prairie Enthusiasts, the Nature Conservancy, and the Wisconsin Department of Natural Resources, permitting their use in cooperative burns. Special hands-free harnesses are used.

Fire protective clothing We wear Nomex fire protective clothing.

Mule pumper unit
Truck pumper unit
Use of the drip torch
   
Worker equipped with fire-resistant jump suit of Nomex. The water can is mounted on a used knapsack frame.

 
Custom-made signs are used at the road corners to inform people of what is going on. If there is any danger of smoke blocking the road, personnel are assigned to control traffic.  

 
 

Summary of Burns Carried out at Pleasant Valley Conservancy

Most of the 140 acres of Pleasant Valley Conservancy has been burned at one time or another, and many areas are burned annually. The table below provides a brief summary.

Area Units Type of habitat Character Frequency of burns Notes
Barn Prairie 0.8 acres Planted prairie Wet mesic Annual ( spring or fall) CRP
Crane Prairie 3 acres Planted prairie Wet mesic Annual (usually spring) Wooded marsh edge restored
North-facing slope 15, 16, 17 Woodland Mesic Rarely (twice since restoration began)  
Pocket Prairie 4.5 acres Planted prairie Dry mesic to wet mesic Annual (usually spring) CRP
Ridge Prairie 2 acres Planted prairie Dry mesic Annual (usually spring) CRP
Savanna 8, 10, 11, 12, 19, 21 Restored savanna Dry mesic to mesic Annually (fall or spring)  
South-facing slope 1, 2, 3, 4, 5, 6, 7, 9 Prairie and savanna remnant Dry mesic Annual (spring)  
Toby's Prairie 3.5 acres Planted prairie Dry mesic Annual (spring) CRP
Valley Prairie 4 acres Planted prairie Dry mesic to wet mesic Annual (usually spring) CREP
Wetland 40 acres Marsh, sedge meadow, shrub carr, stream bank Wet (standing water) or wet mesic Whole wetland once (F&WS); small parts occasionally  
Basswood area 20 Woodland Mesic Annually (fall or spring) Faces steep ravine

CRP: Conservation Reserve Program; CREP: Conservation Reserve Enhancement Program