natural chicago
THE MIGHTY OAK Chicago Region Works to Protect Keystone Species
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hriving 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 (Chicagorti.org/OakRecovery). 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 (crti.org). 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
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and animals can thrive (FieldGuides.FieldMuseum.org/sites/default/files/rapid-colorguides-pdfs/500_usa-common_oaks_of_chicago.pdf). “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. The Oak Ecosystem Recovery Project was established in 2015 after surveys of the Chicago region showed that only 17 percent of the original oak ecosystems were left. As trees grow old, saplings that sprout from seeds, like acorns, grow and replace the old ones. “But oak trees are not regenerating,” Scott says. “Oaks need light as young plants to grow, and the sun isn’t reaching them because they are living in a very dense canopy.” Hundreds of years ago, Native Americans managed the forest with fire, creating a more open canopy. Maples and non-native buckthorn are part of the problem. “Young maples don’t need as much light to grow, so they outcompete the oaks,” Scott explains. Buckthorn, introduced from Europe, “creates a dense thicket and takes away the sunlight needed by young oak saplings. It also creates a chemical in the soil that makes it inhospitable for young oaks to grow. Buckthorn provides berries, which birds eat, but it’s not healthy food. It’s low in fat and nutrients.”
Photo by Peggy Malecki
by Sheryl DeVore
