Beth Botts, Chicago Tribune
In the treasure chest of autumn color, you're especially lucky if you find the burnished gold of oaks.
Oaks are what ecologists call "keystone species," the foundation of living communities. With their spreading branches and nutritious acorns, they provide shelter, food and other benefits to so many other kinds of plants and animals that entire ecosystems depend on them.
"We know that hundreds of species rely on local oaks," says Robert Fahey, forest ecologist at The Morton Arboretum in Lisle.
In the forests and savannas that came before Chicago and its suburbs, oaks were the dominant trees. They are so important throughout the state that Gov. Bruce Rauner has declared October as Oak Awareness Month — or "OAKtober," as its promoters call it.
They're calling attention to oaks because these native trees need help to keep their important place in our forests and communities. As the city and suburbs were built up, conditions changed so much that not enough young oaks are able to take root and grow — unless we plant them.
So consider a native oak whenever there's a chance to plant a tree. Oaks will grow to be large trees, so it's important to give them plenty of space, well away from buildings and power lines, says Doris Taylor, plant information specialist in the Arboretum's Plant Clinic. Although many landscapers and homeowners fear oaks are too slow-growing, in fact their growth rate is about average once they're established, she says.
Among the native oaks most often recommended for residential sites in the Chicago area are white oak (Quercus alba) and swamp white oak (Q. bicolor). Both are large, strong, adaptable trees, Taylor says.
But it's important to plant a wide variety of trees in our neighborhoods, including different species of oaks. Matt Lobdell, curator and head of collections at the Arboretum, suggests other options such as shingle oak (Q. imbricaria). Its big, handsome, shiny leaves look more like laurel leaves than our classic idea of an oak leaf.
Chinkapin oak (Q. muehlenbergii) is another native oak that can thrive in a yard, Lobdell says. It has long, shiny leaves with wavy edges.
For a parkway or a smaller garden, consider the hybrid Ware's oak (Quercus x warei). This tall but relatively narrow tree — about 25 feet wide when it has grown 40 to 50 feet tall — is named after George Ware, the late tree hybridizer at the Arboretum. It's a cross between English oak (Q. robur) and swamp white oak.
Any of these oaks — especially native oaks — will provide acorns and homes to a wide variety of wildlife. You can learn more about oaks in the Arboretum's Tree and Plant Finder, or search for other trees through the Northern Illinois Tree Selector.
As with any tree, it's important to plant an oak in a wide, shallow hole that is not too deep. A new tree will need regular watering for the first two years, and even a mature, established oak will need to be watered in times of drought, according to Beau Nagan, arborist at the Arboretum.
With a good start from an appreciative gardener, your young tree can grow to help keep our region's oak heritage rich and strong.
Beth Botts is a staff writer at The Morton Arboretum (www.mortonarb.org) in Lisle.
For tree and plant advice, contact the Arboretum's Plant Clinic (630-719-2424 orplantclinic@mortonarb.org).
