Later this month, Kevin Flynn will do something he is passionate about, something he does regularly, something American Indians did for generations. He will set fire to acres of native prairie plants near Lincoln Marsh in Wheaton.

“That's what (the plants) enjoy,” he said.

Each year, prairie grasses in the Chicago area are intentionally set on fire to kill off invasive weeds and encourage native plants to grow stronger. The fires control the top layer of vegetation and expedite the return of nutrients to the soil.

Terra Johnson, Lincoln Marsh program manager for the Wheaton Park District, said fire has always been a natural and important ingredient of a healthy ecosystem. That is why, in the fall and spring, the park district, which maintains Lincoln Marsh, performs prescribed burns to some of its land.

This year, the burns are on hold until the land dries from recent rain.

Flynn, a conservation manager for the Wheaton Park District, compares the seasonal burns to the rhythm of a drum.

“I am a believer in every year,” he said. “We don't want to be off, because that allows for an invasive species to move in.”

But burning all of the land that needs to be burnt is not logistically possible, as Flynn said there is more land than manpower.

“We have so many parks that have little areas that have native plants ... that it would be, you know, just a huge maintenance if we wanted to burn it,” he said.

Flynn is confident he will have the opportunity to burn land this fall before too much snow falls. He said there is no way to predict when the burns will occur, and that it all depends on dry conditions.

“You can kind of feel it in the air,” he said. “However, I do try to tell people it’s around Thanksgiving. That’s usually around the time that plants become dormant.”

When the tops of native plants die, their roots below are very much alive. That is why the burns do not kill them. Flynn said this is a result of generations of controlled burns performed by American Indians. He says the plants grew up with the area’s aboriginal inhabitants.

If the fall burn is skipped, the leaf litter and grasses create a micro-climate that is too cold.

“The plants don’t really like that,” Flynn said.

If the land is burned before winter, the black ash attracts sunlight and warms plants’ roots. This warmer micro-climate prompts some plants to sprout again, attracting animals. Flynn said that is another reason American Indians intentionally burned the land.

“It was a way to attract animals all year-round,” Flynn said.

To Flynn, what makes the effort to burn the land worth it is seeing hundreds of species blooming throughout the year “thanking us.”