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What's New: Around the Region

Member Spotlight: Oak Science

Monday, October 12, 2015  


Pictured: Bob Fahey and Lindsay Darling

The Morton Arboretum's team of scientists work steadily to dissect the complexity of oak ecosystems.

We interviewed two of these researchers: Bob Fahey, Forest Ecologist, and Lindsay Darling, Research Assistant, at The Morton Arboretum.

Q: What is the big deal about oaks - aren't other trees important too?

A: Oaks were the most abundant tree species before Euro-Americans colonized the region; they made up around 60% of all of the trees. Oaks are a keystone species, and form the structure that characterizes Chicago's ecosystems. Wildlife and plants depend on this structure, and if we lose oaks many of these other species will be imperiled as well. If we keep oaks and oak ecosystems healthy, then other trees, animals, and plants will also thrive.

Q: What is your favorite plant or animal that oak ecosystems support?

A: That is a hard one, and you probably want us to say something other than oaks. By and large, oak ecosystems are incredible because they offer such rich biodiversity. But if you're going to make us chose a single species we'll take the pileated woodpecker. They are big, impressive birds that make our hearts jump every time we catch a glimpse of one. In terms of plants, we'll go with the American hazelnut.

What does an oak ecosystem look like and where can I find one?

Q: Oak ecosystems are quite varied. They span from open savannas, where there are only a few trees per acre, to dense forests. A diverse array of plants grow under oaks. In savannas, this includes grassy species like you'd see in a prairie, along with unique flowering species like fringed gentians. Oak forests are characterized by abundant ephemeral spring flowers, shrubs, sedges and asters. Most of the natural areas in the region's forest preserves feature oak ecosystems, although they are frequently in poor health due to fire suppression and invasions from exotic species like European buckthorn. Some of the best oak ecosystems in the region that we've seen have been at Glacial Park in McHenry County and Ryerson Conservation Area in Lake County, but there are lots of great examples.

Q: As scientists, what is the most interesting discovery you've uncovered in the research for this recovery plan?

A: We've known that oaks have been declining for a long time, but the simple number that oaks went from 60% abundance to less than 20% in the last 150 years is harrowing. Also, we learned that 70% of remnant oak ecosystems are privately owned. Uncovering these powerful statistics are important to solving the problem. 

Q: Now that we know oak populations are declining, what can we do to fix this?

A: Oak ecosystems need disturbance. Fires used to be frequent across the region, but they have been restricted in the last 150 years. We need to restore these disturbances to the region to create situations where oaks can thrive. However, bringing fire back isn't always enough. We must eradicate buckthorn and other invasive species. Buckthorn creates a dense shade that oak seedlings and other native species cannot grow through. Additionally, because fire has been restricted for so long the forest has grown far more dense than it ever was historically. In order to restore light levels to the forest floor it is occasionally necessary to remove larger, canopy level trees.

Q: What is the biggest challenge facing the oak recovery effort?

A: The most important thing that the oak recovery project must do is to educate the public about the importance of oaks. Restoring oaks cannot be done by natural area managers alone. In more urban areas residents need to bring oaks into their own landscapes and along our city streets and parks whenever possible. Across the region, 70% of the remaining oak ecosystems exist on private property. Reaching out to these landowners and making sure that those areas are protected and well managed is imperative. The story of oaks must be widely told and broadly understood.

Q: How do you think climate change will impact oak ecosystems?

A: The ranges of our oak species extend far to the south, and oaks tend to be resilient to drought and higher temperatures. However, there's also a good chance that the stress associated with climate change will make oaks (and every other tree species) more susceptible to disease and pest impacts. Climate change could also change oak ecosystems by negatively impacting some of the other plants and animals that live in those areas.  


Chicago Wilderness is leading a coordinated recovery effort to preserve, restore, and expand oak ecosystems across the region. Thanks to lead collaborators from Lake County Forest Preserves and The Morton Arboretum as well as funding from the USDA Forest Service and Fish and Wildlife Service, Chicago Wilderness has launched an Oak Ecosystems Recovery Plan. View the Chicago Wilderness Oak Ecosystem Recovery Plan.