Why the Morton Arboretum is removing hundreds of trees

Hundreds of trees are being cut down at the Morton Arboretum in Lisle as part of a multiyear restoration project along the river that flows through the 1,700-acre property.

Crews have been removing trees and shrubs - mostly invasive plants such as buckthorn - for more than a month along a 1.5-mile stretch of the East Branch of the DuPage River.

But the work recently shifted to areas along Route 53, which runs through the middle of the arboretum, and has drawn the attention of many passing drivers.

Any project that involves removing large numbers of trees is a rare step for the outdoor museum that opened in 1922 to champion the value of woody plants.

"We know people would be concerned because it's unusual that we would be cutting down trees," arboretum spokeswoman Kelley Regan said. "But it is for a good cause in the end."

The arboretum and the U.S. Army Corps of Engineers launched the roughly $5 million project with an eye toward restoring portions of the DuPage River to its more natural state.

The project - the cost of which is being split between the arboretum and the Corps - is meant to reduce the unintended consequences of work done in the 1920s to straighten the river when surrounding land was being farmed.

Because the river is so straight in the arboretum, water rushes through it and erodes the banks, leaving them artificially steep.

"The riverbanks start to almost get concave," Regan said, causing some trees to fall into the water. "It's not the way the river should be."

As part of the project, crews will regrade the eroded banks to give them a gentle slope.

To do that, though, at least 600 trees must be cut down.

"The removal of select trees is absolutely necessary to regrade the soil and stabilize the riverbanks where erosion is severe, which will result in better habitat in the future," Regan said.

She stressed that most of the trees being removed are invasive.

"They're not good trees anyway," Regan said. "We don't want invasive species in our ecosystem. They destroy the ecosystem."

In cases where the river runs by some of the arboretum's more important collections, steps are being taken to protect the trees. Some, for example, are being transplanted to other parts of the arboretum.

In the meantime, the arboretum has been keeping visitors and members informed through a Web page and interpretive signs.

Once the regrading is complete, wildflowers and other native plants will be added along the riverbanks.

"It will be really nice," Regan said. "Our goal is to attract more wildlife - more native birds, native plants."

The path of the river won't be changed, but boulders and other features will be added to slow the water flow.

"All in all, it's good for the ecosystem," Regan said. "We won't have the erosion, which was really the problem. And it will improve the water quality of the river as well."

The entire project is expected to be done in five years, but most of the work will be finished in the first 18 months.

And what will happen to all the wood from the trees that have been cut down?

"The arboretum is committed to sustainability and recycling whenever possible," Regan said. "Wood from the trees is mainly being used for mulch or firewood. Wood from some of the larger trees will be saved and may be used for demonstration and educational programming - we don't know yet how feasible this is, but we're looking into it."