Chicago’s derecho damage points to need for more native tree planting, U of I scientist says

Most people are probably like my wife and I, who have traveled the city awestruck by the widespread tree damage caused by the Aug. 10 derecho that slammed through neighborhoods with 75 mile-an-hour winds.

We’ve observed only a small portion of what city officials tell us were thousands of downed trees — some that landed on cars, garages and houses — and marveled at the seeming randomness of nature’s destructive force.

Greg Spyreas came away with a different take.

“What I saw wasn’t random at all. As I walked around, I shook my head at the utter predictability of it,” Spyreas wrote in a letter to the Sun-Times.

Spyreas, 45, a botanist who works as a research scientist with the University of Illinois at Urbana-Champaign, said the damage was primarily the result of poor decisions made over many decades about which trees to plant.

Instead of native trees adapted to Midwestern storms, Chicago’s streets are lined with “non-native, ornamental and/or fast-growing, weak-wooded trees” that are the first to fall, Spyreas said.

“I see block after block of Norway maples snapped in half, European lindens completely uprooted, Callery pears split and shredded,” he said, naming some of the main culprits, their presence attributable to shortsighted fads.

To try to see what Spyreas sees, I took a walk with him Friday south of Welles Park near where he lives. It wasn’t the hardest-hit part of the city, but it took a punch, and the scars were evident.

We paused at a stand of Norway maples along Montrose Avenue that seemed to have weathered this storm well but might not the next.

“They’re 40 years old. They’re at the end of their life span,” Spyreas said.

The Norway maple is a good-looking tree. It grows fast and reaches for the sky, Spyreas said, making that nice circular shape on top like you see in a kid’s drawing.

But its wood is weak, and it measures life in decades, not centuries.

The next time we came across a Norway maple, it was badly damaged. By the end of our walk, Spyreas estimated that 75 percent of the damage we’d seen was to that one tree species.

We passed a pair of ash trees looking a little worse for wear. The ash is a majestic tree native to our area but, as most folks know, has fallen victim to the emerald ash borer.

Twenty percent of the trees in the city are ash, Spyreas said, and most will be coming down in the next five years, testament to the need for diversity in our tree population.

Our next stop was a healthy little tree.

“That’s a red oak, and that’s a good choice,” Spyreas said. “Whoever did that knew what they were doing.

“And over there, they didn’t know what they were doing,” he said, pointing to a Callery pear with a missing limb that had fallen into the street. “It’s the biggest fad tree that’s actually a piece of garbage.”

A neighbor told us the fallen limb had landed on a car.

Spyreas really hates Callery pears, so I didn’t tell him we planted some type of ornamental pear when we lived in the suburbs.

Rounding the corner, we found another toppled Norway maple. Spyreas inspected it closely and said the trunk and roots appeared healthy.

“You would have thought this one would have done better,” he said.

Which raises the obvious point that any storm of the derecho’s magnitude is going to cause tree damage. But Spyreas said it will be much less if we plant better trees.

It’s not like our choices are limited.

“Sassafras, flowering dogwood, serviceberry, hawthorn, Iowa crabapple, Canadian plum, redbud, blue beech, juniper, white pine, eastern hemlock, American elm, American sycamore, American beech, tupelo, catalpa, magnolia, walnut, hackberry, Ohio buckeye, Kentucky coffeetree and tulip poplar can all thrive in the city,” Spyreas said.

Most of the trees that sustained major limb damage Aug. 10 will die within the next five years, Spyreas warned.

With so many trees needing to be replaced, he said it’s a good time for homeowners to consider their options — and take the long view. A native sugar maple, for instance, can live hundreds of years.

Spyreas had one last piece of advice.

Don’t ever park under a Norway maple or a Callery pear.