After a tough year, trees recover from drought in time to display fall colors

Despite a year of extreme dry and wet weather, arborists say Illinois trees still have a shot at a vibrant autumn transition - as long as the next few weeks deliver them warm, sunny days and cool nights.

A national map from the Smoky Mountains website predicts when trees will showcase their most vibrant colors - down to the day. The map, which can be found at tinyurl.com/2023FallColors, predicts the greater Chicago area will see its peak Oct. 23.

"I'd say that what we saw in 2022 with those fewer extreme weather events resulted in a rich and vibrant fall color season. This year, the story is still being written," said Spencer Campbell, the plant clinic manager at the Morton Arboretum.

That story began in spring and summer, when the weather has a huge effect on fall color. When the statewide drought hit in the early summer after a flux of cold and warm spring temperatures, many trees had trouble producing and supporting their leaves.

"Most trees in the region put out their leaves this spring during a stressful time of drought, and species have responded differently to those conditions," arboretum forest ecologist Christy Rollinson said in a press release. "Some trees whose leaves emerge late in the year, like honeylocust, seem to have made fewer and smaller leaves, while trees that leafed out earlier showed a range of responses, including discoloration and leaf curling."

But then July came, and it wasn't just any July. It was the second wettest July in the area's recorded history, behind that of 1936.

"Most of the visible signs of drought were alleviated, and a lot of trees experienced new spurts of growth," Campbell said. "That quick recovery after the rainfall was (very green) and in some cases is now higher than average, according to satellite imagery."

Because yellows typically emerge first while oranges and reds come later, Campbell said it's difficult to nail down a "peak" for fall color.

"Generally, you're going to see lots of color whenever you go out in the months of September and October. But when they're all coinciding, I would say the next two weeks or so, because we're going to start to see some more of the reds and oranges. It really just depends on the weather."

That's because the chemical that creates those oranges and reds is a response to sun exposure. If trees capable of making that chemical are treated to warm, sunny days in the next few weeks, there's a good chance their colors will bloom vibrantly.

Rollinson added that the year will give researchers "an incredible amount of information" about how early, mid- and late summer each influence the timing and vibrancy of fall color.

As climate change increases the likelihood of extreme temperatures, scientists are concerned that events like heat waves, drought and flooding could disrupt the timing of when trees change color and dull the radiant hues that many look forward to seeing each fall.

"The conventional wisdom is that healthy trees will have the best fall color, and we really saw this in 2022 where there were fewer extreme weather events," Rollinson said.

The arboretum is one option for leaf peepers who want to see a diversity of trees - including whole collections dedicated to species known for bright color.

According to the arboretum's latest weekly fall color report, "yellows and golds are beginning to emerge most noticeably in the Elm Collection near Parking Lot 1. Elsewhere in the collections, yellows are showing in hackberries, redbuds, corktrees, coffeetrees, honey-locusts, hickories, black walnuts, cottonwoods, witch-hazels and catalpas. A few viburnums and flowering dogwoods have turned purple-red, adding color to semi-shaded areas, while sumacs, Virginia creeper and poison-ivy have turned vivid red in spots with full sun."

In general, some of the best species to seek out anywhere in the suburbs are sugar maples, red maples and honeylocust. Maples tend to concentrate further north in hardwood forests, especially in Wisconsin, and honeylocust are more centralized in the southern half of the state.

Trees aren't the only plant displaying interesting color right now, Campbell added.

"I always like to throw in the idea about our native plants in herbaceous fall color as well," he said. "There's a lot of color changing in our natural areas, the Schulenburg prairie, for example. It's just as exciting and a neat way to enjoy fall color."

• Jenny Whidden, jwhidden@dailyherald.com, is a climate change and environment writer working with the Daily Herald through a partnership with Report For America supported by The Nature Conservancy. To help support her work with a tax-deductible donation, see dailyherald.com/rfa.