The Mighty Oak

Chicago Region Works To Protect Keystone Species

Thriving in Michael and Kendra Eiermann’s Niles backyard is a centuries-old bur oak tree that stands more than 80 feet tall with a diameter of 57 inches and a canopy stretching more than 107 feet.

That the oak is still standing is a testament to folks like the Eiermanns, who along with countless other private residents and public entities, are working to protect not only the many species of oaks native to the Chicago region, but also the ecosystem in which they live. The Eiermanns recently earned a certification of achievement for stewarding their oak tree from the Chicago Region Trees Initiative, headquartered at The Morton Arboretum, in Lisle.

The coalition of organizations works to improve the urban forest where people live, work and play. It also oversees the Oak Ecosystem Recovery Project for the region. Toni Dati, street superintendent for the village of Niles and municipal director of the Illinois Arborists Association, says, “I played under the Eiermanns’ oak when I was a child. It is a magnificent tree.”

The tree was likely standing before the Europeans settled in the United States. “Back then, oaks were by far the most dominant tree species,” says Lydia Scott, director of the Chicago Region Trees Initiative.

Over the past century, the number of oak trees and the acreage of ecosystems in which they thrive have been declining in the region. Lack of sunlight, invasive plants, disease and development have contributed to the decline.

Eight native oak species are common in the Chicago region. These include bur, white and red oak, which grow in harmony with shagbark hickories and other trees where hundreds of other species of plants and animals can thrive. “Oaks in our part of the country are considered a keystone species,” says Lisa Haderlein, executive director of The Land Conservancy of McHenry County.

“Normally, people think of a predator like a lion or wolf as a keystone species,” Haderlein says. “We don’t have those. But we do have these amazing trees that support a wide diversity of other plants and animals.”

Birds, insects, salamanders, frogs, butterflies, bats and even the fungi beneath the soil co-evolved with the oaks and are all tied to one ecosystem. “By helping oaks, you help a whole suite of other species,” Scott says.

An acorn and bur oak tree leaves. Photo by Sheryl DeVore

 Oak trees also are contending with diseases such as wilt, which particularly affects red oaks and came from Mexico or South America perhaps a century ago. A newer and slower-spreading disease, bur oak blight, is caused by a native fungus, and is being watched by local arborists and land managers. The main task now for forest preserve and conservation districts in the region is to remove buckthorn and open up the canopy in the oak ecosystems they manage.

“For example, the Lake County Forest Preserve is creating canopy gaps,” Scott says. “They are carefully selecting trees for removal to provide light for young oaks. Age diversity is important in healthy woodlands so that there are new trees coming up to replace those on decline. Oaks grow in light gaps, and increased age diversity of oaks is really important.”

Work being done on public and private lands to help the oaks is showing early signs of success. In the Lake County Forest Preserves and The Morton Arboretum, the smaller oaks are starting to grow and birds such as red-headed woodpeckers that need open oak woods in which to breed are increasing in numbers.

Private Landowners Contribute

“But 70 percent of all the existing oak ecosystem in northern Illinois and southeastern Wisconsin are on private lands,” Scott says. So the recovery project works to not only enhance oak ecosystems on public lands, but also to improve those held privately. “People’s yards connect to natural areas,” Scott says. “The key is to provide information to private landowners about practices they can undertake to improve ecosystem health on their properties.”

A bur oak tree at Wolf Oak Woods in McHenry County is more than 350 years old. Photo by Whitney Rupp.

The Oak Ecosystem Recovery Project is working with municipalities near the 14,000-acre Cook County Palos Preserves to enhance private oak woodlands. “One of the challenges that the forest preserves have is that while they’re battling buckthorn on their property, the people who live nearby don’t know it’s a problem,” Scott says.

A recent U.S. Forest Service grant is providing funding for forest preserves and land trust organizations to work with private landowners on caring for oak ecosystems. They learn to replace buckthorn with native species and how fertilizers and pesticides impact the ecosystem, not just their property.

“We asked each county to identify one priority oak ecosystem where they are working to help engage private landowners,” Scott says. “Each of them has undertaken a range of activities and outreach.” The Land Conservancy of McHenry County, for example, has created the 5,000 Acre Challenge. “In McHenry County, we have about 5 percent of the oak woodland areas remaining that would have been here historically, and 85 percent of that is on private property,” says Executive Director Lisa Haderlein.

The challenge becomes to encourage oak woods owned by private landowners to join the effort to save and protect them, bringing the total acreage of managed oak woodlands to 5,000 acres.

Since the challenge began in January, McHenry County now has more than 4,100 acres of oak woods being cared for by private landowners and public entities. Private landowners recently committed to maintaining more than 300 acres of oak woods, and the Conservancy is working with the village of Bull Valley, a community of 1,100 people and nearly 1,500 acres of oaks, to inform residents about the challenge. “When 5,000 acres is reached, we’ll raise the bar. We want to get to 18,000,” Haderlein says.

The nonprofit also owns and manages roughly 600 acres in McHenry County, many of which contain oak ecosystems. Wolf Oak Woods demonstrates what landowners can do to enhance these ecosystems. “Wolf Oak Woods is named in honor of one of the most amazing bur oaks in the area,” Haderlein says. “It’s at least 350 years old. The branches come down to the ground. It’s spectacular.”

Since its acquisition in 2016, volunteers have worked there to open up the woods, which have attracted red-headed woodpeckers to nest. “This spring, there was a blanket of wild geraniums beneath the oaks,” Haderlein says. “We didn’t plant the geraniums. They were just there waiting for the sunlight.”

Sheryl DeVore has written six books on science, health and nature. She also writes nature, health and environment stories for national and regional publications. Connect at [email protected].

Celebrate Oaktober 

• Clear non-native shrubs such as buckthorn and Amur honeysuckle to let the sun shine in.

• Plant oaks in sunny areas. Take advantage of plant sales and giveaways. For example, the Conservation Foundation, recently gave 50,000 free oak trees to Cook County residents.

• Volunteer to plant and care for oak trees and ecosystems at local nature preserves.

• Learn more at Chicagorti.org/OakResources.