Editor's note: Last of three parts
Gurnee streets supervisor Jake Balmes became the village's first forester in 2000, although as a certified arborist he knew when he joined the staff in 1995 that the village was overplanted with ash trees.
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He tries to explain how this happened.
First, the Dutch elm devastation of the last century was not personally imprinted on Gurnee. Even its older neighborhoods did not have the tree-lined streets enjoyed by towns closer to Chicago, Balmes said.
As subdivisions multiplied and the village boomed, on paper Gurnee was asking developers for tree diversity.
But, "I think most communities worry first that the roads are going in right, the curbs are right, the streetlights and the water mains," he said.
"A lot of times, even today, forestry is often overlooked. It's not considered an essential thing."
To avoid another regional catastrophe like the emerald ash borer or Dutch elm disease, arborists say Chicago area communities, developers and residents have to agree that a town's overall tree stock must be heavily diversified.
As well, nurseries must make less common trees more readily available.
To do that will take knowledge and political will, two commodities that could be in short supply as developers and municipalities try to bring residential and commercial developments in at budget.
But how diverse should a municipality's public tree population be? Why did the suburbs end up with so many ash trees after the lessons learned by Dutch elm disease? And what is going to make communities do the smart thing this time?
Ideal diversity means a community has only 10 percent of a single genus, according to the Illinois Department of Agriculture. This challenging standard means all kinds of maples, for example, from red to Norway or silver, count as one genus.
That didn't happen very often over the last 40 years. Ashes were attractive because they grew quickly and thus inexpensively, thrived in the dreadful environment of parkways, had few known pests and provided the shady canopy residents mourned with the loss of their elms.
Balmes can talk about the expense and heartbreak this monoculture causes in Gurnee today. But he also understands officials decades ago who looked at the self-sufficient ash and saw less future maintenance for village crews.
Nurseries -- the source of all these trees -- were another part of the equation, said Robert Benjamin, who was a Chicago forester from 1971 to 2003.
Few trees were generally available that were considered strong enough to survive the harsh urban environment alongside a city street, with its heat, sporadic watering, salt and often dreadful soil, said the Lombard resident, the recent recipient of an Arbor Day Foundation award.
Nurseries grew "bread and butter trees": maples, ash and locust.
"You can't buy a tree that nobody grows," Benjamin said.
Imagine trying to convince officials accustomed to looking for the low bid to pay $35 for a ginkgo rather than $9 for an ash, said Benjamin, who said achieving tree diversity in Chicago was far from easy.
Critically, at that time when small communities burgeoned into modern suburbs, many were understaffed.
Developers, who also faced cost pressures, did not deal directly with municipal foresters but with officials whose mandate was to encourage development and increase the tax base, Benjamin said.
"Even today it's an issue," he said. "If you have a $3 million project and you've got to cut costs, the first thing that gets cut is landscaping."
It's not far-fetched to imagine developers again pitching a single "ideal" tree to municipalities by arguing its cost-effectiveness would make the difference between moving ahead with a project or not, said University of Illinois Extension Entomologist Phil Nixon.
Private trees key
Scott Schirmer, EAB program manager for the Illinois Department of Agriculture, urges municipalities to inventory their trees so they know the variety, size, age and condition of their populations when it's time to replant.
That includes trees on private property. Suburban yards contribute more than we think to critical diversity, said Mike Raupp, professor of ornamental horticulture at the University of Maryland.
A specialist in how plants escape the ravages of insects, Raupp urges people to "plant flowering trees, shrubs, perennials, flowering everything; natives are better, but plant exotics, too, if they're not invasive."
Beneficial insects -- the basic food for birds -- need pollen and nectar, he said at a recent conference Bartlett Tree Experts held at the Chicago Botanic Garden.
A tree standing alone will attract predatory bugs, said Raupp. Studies show adding even a few different flowering plants can multiply the number of natural enemies for those predators.
The tree history of the U.S. shows the devastation of monocultures, both natural and man-made. The next worry might be maples -- as suburbs are planted heavily with them because everybody loves the brilliant fall colors.
Can we do it?
Schaumburg Village Manager Ken Fritz believes developed suburbs like his have learned their lesson. Schaumburg had about 12,000 public ash trees when the emerald ash borer was first discovered, and all but 700 "high value" trees may eventually be lost.
Under Schaumburg's reforestation plan, no single tree species will be allowed to make up more than 7 percent of the total population.
And while there is no state or regional directive pushing tree diversity, forces are aligning to make variety the norm, said Schirmer. He sees more municipalities producing diverse planting lists for parkways and public grounds.
"Communities are starting to look at more unusual, less known, less popular trees," said Schirmer, suggesting the catalpa, Kentucky coffee tree and Turkish filbert should be on their lists.
Nurseries will also push more variety at the same time homeowners and municipalities are seeking it, he said.
Some communities frustrated by a lack of tree choices are achieving diversity by contracting with nurseries to grow specific trees, said Lydia Scott, community trees program manager at the Morton Arboretum.
She works with municipalities to broaden their list of desirable trees and says nurseries are themselves diversifying their stock because of the emerald ash borer.
Municipal codes often do not require developers to provide tree diversity. Instead there are lists of allowed trees, which can be updated as varieties get overplanted. And developers often must provide landscape plans, then municipal staffs and other officials can urge changes.
Benjamin says his fellow foresters have more weapons today to convince officials and the public of the economic and environment importance of trees.
Mark Spreyer, naturalist at Stillman Nature Center in South Barrington, is encouraged that government grants for replanting trees often encourage species diversity.
There's beauty in diversity, too, says Schirmer.
"I think it's fun to turn a corner and see different trees of different heights and different colors with different smells, too," he says. "One that turns purple and one yellow in the fall."
• Daily Herald staff writer Melissa Silverberg contributed to this report.