Fall 2001

Designing the Burn

by Joe Neumann

I’m on the phone with the Palos North fire department in southwestern Cook County. “Is McMahon Woods in your jurisdiction?” After checking the location, the woman quickly confirms that I have called the right place.

The preparation for a controlled burn begins long before the day the fire is set. Each site needs a written burn plan. As volunteer steward, I find phone numbers for an extensive list of fire, police, and district departments that need to be informed when a burn is scheduled. The burn plan includes these phone numbers along with the procedures, conditions, equipment, and crew needed to carry out the burn. To prepare this section of the plan, I walk McMahon Woods with John Raudenbush, restoration forester for the Forest Preserve District of Cook County.

Much of McMahon Woods is now a formidable thicket. But it was once one of the most open sites in the district. A wave of non-native viburnum drowned the formerly open oak savanna. European buckthorn swallowed what was once prairie. Fire would have kept the invasive brush under control. John and I make our way into the interior along a brush-choked footpath. Once we leave the footpath, conditions get worse. We duck or crawl under the often thorny branches.

Our destination is the most significant natural feature of the site – a specialized wetland called a fen. The fen’s alkaline waters seep out of the ground after making a subterranean journey from the uplands to the north. When people emerge into the fen, after navigating the thicket, they often gaze around in relief and declare: “I can breathe again!” Nature has a similar reaction. The thicket has a stifling lack of diversity, while the fen bubbles with butterflies and wildflowers.

As we make our way through the thicket, John and I discuss details for conducting a burn here: crew members (8), temperature (maximum 70° F), relative humidity (at least 25 percent), wind speed (no more than 20 m.p.h.). One of the most important factors is wind direction. The nearest roads are to the west and north. A wind from these directions will ensure that smoke stays away from traffic. The crew will be equipped with drip torches to light the fire. Flappers and backpack pumpers will be used to control the fire. Two-way radios will keep everyone in communication. A 50-gallon pumper truck will be stationed along 104th Avenue where it can wet down the nearby cattails if necessary.

As we stand on the north side of the fen, John’s gaze crisscrosses the wetland’s width of a few hundred feet. His eyes sweep out along the extended length of the fen that trails away into the distance to the west. He glances back at the thicket to the north and east that we passed through. He glares at the low-grade woods to the south where a massive marsh once existed until it was devastated by the construction of the Sag Channel canal. “On the day of the burn we’ll start in the southeast,” John says as his arm sweeps the eastern end of the fen. “One crew will take the north side and the other the south.” As he talks he seems to see phantom crews moving into position. “The south crew always has to stay in front of the north crew – that’s a must.”

Back in the parking lot, John is soon on his cellular phone. Some assignments on the district’s expanded burn crews have not been finalized yet. Burn season is almost here. Time to put plans into action.