Fall 2001

by Kathleen Kostel

After 15 years of burning, a Cook County forest preserve is a feast of biodiversity all summer long. Photo by Doug Sherman.

I had recently purchased 10 acres of woods and wetlands in northern Porter County, Indiana. I thought, being an environmentally concerned citizen, that I would not touch the property, but rather leave it in its “natural native” state. Little did I know how unnatural it had become through the years.

Standing on my back deck just few short weeks ago, I looked out and proudly admired a forest of dense shrubs and trees. Since then, I’ve written this article. Having talked to lots of seasoned land managers in Chicago Wilderness and having walked my property with one, I now look out and see a wooded area of primarily stinging nettle and brush, mixed in with a few oaks. Still wooded, but a lot less healthy than I had thought. For a truly healthy, diverse woodland, I’ve got some work to do.

A novice bird-watcher, I reach for the binoculars in excitement at the sight of a blue heron feeding on tadpoles on the shore of my one-acre pond. Yet, I can’t help but wonder what other kinds of birds I could enjoy seeing if my land were a more inviting habitat.

Slowly I will make it happen – remove the purple loosestrife, cut back the brushy understory. I’m even considering “girdling” a few invasive trees. This, I’ve learned, is the process of cutting a swath six-inches wide and a quarter-inch deep around a tree’s trunk to kill it without the major expense of hiring a tree removal service. Sunlight will slowly filter back to the woodland floor and the standing snag provides habitat for birds and mammals. Had I been asked about girdling a month ago, I would have referred you to Carson’s lingerie department. Now I recognize that this process will invite more light for native plants and wildflowers, many of which fortunately still exist on my property.

It all takes time, it all takes resources. But as one land manager told me, “In the end it’s worth it.”

We grew up in the age of advertising’s “Smokey the Bear.” We learned that only we could prevent forest fires. A fire in the woods simply spelled disaster.

And yet many public land managers are learning firsthand that too much protection is not necessarily a good thing. Thinning a forested area – through fire, removal by machinery, or other means – can restore an oak woodland community to good health and result in a more diverse and sustainable ecosystem.

Fire controls invasive species and invigorates the oaks and wildflowers. Photo by Joe Nowak.

“There’s an incredible rebound when you open up a forested area,” says Wayne Schennum, natural resource manager for the McHenry County Conservation District. “Much more diversity in plants, which leads to a more diverse insect population and more types of birds.”

The average citizen doesn’t have words to distinguish between denser or more open forests. But there are definite differences. Ecologists define natural forests, woodlands and savannas as three parts of a continuum – based on the kinds of animals and plants that live there. These are correlated with the long-term density of a site’s canopy cover, or tree top “roof.” A long-term canopy cover of 80 percent or more produces a forest. An oak woodland will have developed a canopy cover of 50 to 80 percent, while a savanna has coverage of 10 to 50 percent. Below 10 percent is considered a prairie.

A prairie growing over with brush doesn’t become a savanna, then woodland, then forest. It becomes a degraded prairie. If there were savanna animals and plants living nearby, and if it were being regularly burned and if other problems didn’t intervene, it could become a savanna in time. But that rarely happens these days. When an oak woodland is invaded by maples, it doesn’t typically become a maple forest. The natural maple forest ecosystem needs thousands of interdependent species. Most of them don’t fly through the air as easily as maple samaras. The thousands of interdependent species of the oak woodland die in the shade, and the result is a depauperate ecosystem – where often even the soil washes away.

In the last 20 years, land managers at Chicago area forest preserves and other natural areas have been working to restore densely overgrown woods to original oak woodlands. Employing “prescribed” or controlled burns, and in some instances heavy machinery, as well as following with spot treatments of herbicide, they are reducing invasive plant species to a minimum with great success.

“The results have been fantastic,” says Ken Klick, restoration ecologist with the Lake County Forest Preserves. “It’s exciting to see what returns from the bare earth that had appeared to have died out. Many of our ground layer forbs (wildflowers) responded very well to clearing. And we walk through these areas now and see bluebirds where we didn’t see any before, or towhees, and catbirds.”

Wayne Lampa, an ecologist now retired from the Forest Preserve District of DuPage County, reports similar success at restoration efforts, particularly at Waterfall Glen.“Through burning and improving the general habitat, the natural plant species made a dramatic come back,” Lampa says. “Some plants had reappeared, like Cacalia, pale Indian plantain, which is a big, beautiful plant. We’ve also seen white wild indigos, a legume highly prized by many animals, which when really in its element can stand four feet tall with very large, white pea-like flowers. And there has been a rebound in ferns, such as the bracken fern. They’re now starting to make a good recovery and had almost disappeared from the landscape.

“Once the plants recover we see all sorts of things come in,” Lampa continues. “There were times in late ‘80s we would hardly hear birds at all. But once things opened up again, mice and moles returned. Now we’re seeing hawks and owls, as well as bluebirds and great crested flycatchers.”

In addition to actual restoration work, Lampa says DuPage land managers have completed a “tremendous amount of monitoring and recording” of the return of diverse native species. “There’s been a lot of light monitoring to see what light levels are required for vegetation to come back,” he says. “The preponderance of evidence shows the positive effects on diversity.”

Blue-spotted salamander. Their numbers rise as health is restored to a woods. Photo by A.B. Sheldon/Root Resources

Success in restoring native oak woodlands isn’t always as simple as striking a match. It can require significant resources in terms of time, fire management personnel, and funding. Because of the expense involved, managers carefully select sites based on criteria for restoration. They note certain features and prioritize according to the greatest potential for success.

“It’s like a triage operation,” Klick says. “You learn to read the landscape of a forested area and look for clues or indications of the vitality or recoverability of the woods. You look to see what kinds of stray plants may be along a trailside or at a ‘tip-up’, a spot where a tree blew down, where you can see what came up in the light. That will give an indication of what native species may still be viable in the area.”

Once managers designate a site as having strong potential for restoration, they decide on the approach. A prescribed burn may be planned, according to the season, usually in the late fall or winter when the availability of natural, dry “fuel” is more abundant. With their splayed, curvy “fingers,” oak leaves have an inherent design that allows them to catch fire quickly.

According to Klick, some woodland areas have so few remaining oaks and are so inundated by brushy plants such as Tartarian honeysuckle and European buckthorn, a fire simply won’t burn under the moderate conditions of prescribed fire. This requires initial hand clearing or using machinery to rid invasive brush and woody plants. Machines are generally brought in during the winter so as not to tear up the soil. Afterward, sunlight can reach the forest floor, eventually triggering oak regeneration and the growth of grassy vegetation that can fuel a fire.

While fire can keep invasive plants at bay, it often needs help to eradicate them entirely. Land managers described how fires “top kill” or burn off the brush above ground, leaving the roots and stumps to sprout anew, sometimes with even thicker brush. As a follow-up approach, some managers spot spray herbicide on stumps to eliminate invasive plants down to the roots. “At Old School and Grant preserves in Lake County (IL),” Klick says, “we have gone in with chain saws and mechanical equipment and selectively cleared buckthorn, honeysuckles and ash, both native and non-natives. And then we carefully apply herbicides because you can’t rely on fire alone to control woody plants.”
Once a clearing is complete, land managers will wait a year or two to see what kinds of native vegetation return. In areas where there are few surviving grasses and wildflowers, Klick says, “we introduce seeds to help the process along.”

Two shots of the same woods—Vestal Grove in Northbrook. (Left) Here a wall of European buckthorn grows in a section that has not been burned for six years. (Right) This area looked just like the photo on the left—just 20 feet away. But this area is part of the fire management unit. It's been burned every two or three years since 1980. Photos by Stephen Packard.

The invasive green ash was killed by girdling. Photo by Doug Sherman.

“Deer can be a problem with browsing if their numbers are high,” Schennum says of McHenry County areas. “They will munch away at the native flora. We monitor deer with exclosures, 13 x 13-foot fenced-off areas, to keep the deer out. We then look for the difference in flora inside and out of the exclosure. We also do a winter deer count. We haven’t done culls as of yet, but the numbers are certainly building, and that affects the overall balance of the area.”

At Waterfall Glen, Lampa describes a “recovery of an incredible number of species of plants” through a reduction in the deer population. “At one point in 1991, parts of Waterfall Glen looked as if they’d been mowed,” Lampa says. “There was not a single grass above five or six inches.

“Once we reduced the number of deer, there was an explosion of plants,” he recalls. “There are on the order of around 500 to 600 plant species that are now known at Waterfall Glen, where before there was an incredibly small number. The plants probably had been there at one time but were reduced from too much shade and deer browsing. Even trilliums and onions, which deer highly prize, were coming back just as strong.” Just like too many trees, too many deer will gradually degrade an ancient ecosystem.

Two shots of the the same area in Daniel Wright Woods near Mettawa. On the left—in 1991—trillium carpet the forest floor. On the right—in 2001—most of the trillium are gone, and garlic mustard is taking over. Unfortunately, with soaring populations of white-tailed deer in so many suburban areas, this woods is fairly typical of woods throughout the region. Photos by Doug Sherman.

He continues. “Five years ago, there was concern. People would ask us, ‘Why are you cutting trees?’ ‘What’s going on?’ We’d answer that it creates a better abundance of plants for insects and birds. Now they can simply compare and contrast. They’ll see an area loaded with bur oaks and buckthorn and then look across the street at the Old School Forest Preserve and see a big difference. Our past successes reinforce our efforts.”

Lampa agrees that public influence can make or break the success of oak woodland restoration. “Generally people in DuPage County were very supportive,” he says. “Commissioners take notice when people are supportive. I would go to a commission meeting and hear a commissioner say, ‘I got 14 calls on this last week.’ So when the vote comes up, it sticks in their minds and they know which way to go.

“To generate support I would try to send people to a place like Waterfall Glen so they could see results,” he adds. “I’d also ask them, ‘Please, give us a chance, sit back and see what happens. If you’re still concerned after a few years, call me back and we’ll talk about it.’ I’ve never had one single person call me. If people are willing to be patient and see what happens, they’ll see wildflowers and a greater variety of insects and birds come back where all they saw before was a green wall.”

Lampa says that while much has been accomplished, more remains to be done. “There’s a large number of remnant woodlands and savannas left, and only a fraction have been touched because resources are not there. I don’t think we’ll ever touch all of the oak woodlands in this area,” he says, “and maybe that’s not necessary. Maybe some examples should be left to show in the future what happens to those areas when they’re not managed or touched at all. If people really want to learn more about this, they should check with their local forest preserves or conservation district and find out from them the really good sites in terms of prairies, savannas, or woodlands. Good examples of places that show what works.”

Lampa says that as local citizens understand the need for and process of oak woodland restoration, more people volunteer to help. “For the first few years, I was out there doing a lot of stuff by myself because I was the only person available,” he says. These days the retired Lampa sees an expanded land management staff and a dedicated volunteer team. “You have to keep working on it or nothing will ever get done. Keep looking at the good stuff and what’s been done. Keep plugging away at it. In the end it’s worth it.”

Kathleen Kostel is a former board member of Friends of the Indiana Dunes and
the Shirley Heinze Evironmental Fund. As Director of Communications at Valparaiso University in Valparaiso, Indiana, she frequently hikes in the dunes. Trail 8 in Indiana Dunes State Park is her favorite “because it’s the hardest.”