Why Missouri and Kansas Cities Want to Plant More Tree Species | KCUR

Overland Park, Kansas – Every fall, as temperatures drop, people in this suburb can count on eye-catching displays of richly colored maple leaves.

But maples make up about a third of the city’s street trees, and Overland Park learned the hard way that too much of a good thing can mean too fragile.

So last year, the city put the capuchin on planting more maples.

the Emerald Ash Digger — a bright, green little hitchhiker from Asia with a voracious appetite for a different beloved street tree — taught this town and others in Kansas and Missouri a painful lesson.

Now some communities are hedging their tree bets and protecting local home values ​​and tax bases by embracing diversity.

Streets with mature trees command higher house prices, ease the summer days, and attract more people outdoors to get fresh air, walk and chat with neighbours.

“The emerald ash borer will likely kill all of the ash trees in Overland Park,” city spokeswoman Meg Ralph said in an email. “The more diverse we have in our tree canopy, the more resilient it will be when the next invasive species or tree disease comes into our community.”

Ash made up about a quarter of the city’s street tree canopy when the insect arrived a decade ago.

In a completely globalized world, the city has no guarantee that a maple syrup-flavored bug won’t turn up next.

So last fall, I downed their maple forests from List of trees People can plant along residential and commercial right-of-way streets – like that strip of grass between the street and the sidewalk.

Currently, Overland Park will not add more maples to any property in the city. It will steer developers away from those trees, too. Builders require city forestry approval for their landscape plans.

“We are working with developers to ensure that maples are not planted in new private development,” said Ralph.

Replacement price for 1,700 ash trees

Winterset at Lee’s Summit, Missouri, illustrates the stakes.

Ash trees are celebrated for their purple, red, and yellow fall leaves. So streets lined with hundreds of tall, graceful trees seemed like a dream when the developers of Winterset began in 1990—before the emergence of emerald ash borers in Michigan.

“It ended up being a huge mistake, because we did a monoculture,” developer David Gale recalled.

More than a decade later, Gil heard of the invasive beetles eating their way through American cities and forests, decimating trees. Neighborhood bosses keep track of the situation.

“You can see the radius expanding and expanding,” he said. “You just have to face reality.”

By the time the invading bugs approached Lee’s Summit, 900 homes in the Winterset growing region had enjoyed 1,700 ashes. After two and a half decades in the ground, it averaged 40 feet in height.

“You can imagine how attractive they are,” Gale said.

Winterset Council voted to remove and replace the trees. The work finished in 2021 and cost $475,000.

This time, the community planted a mixed street canopy.

Residents chose from nine local hardwood species, including oak, maple, basswood, and black gum.

The replacements are still relatively young, but once they’re ripe, they’ll feel like an expanse of deciduous forest in and around Winterset.

Picking trees in a globalized world

Landscapes have long capitalized on the appeal of visual symmetry by planting dozens or hundreds of identical trees at a time.

elm. red maple. ash. Bradford pear.

“Whatever tree was preferred at the time,” said Kim Bomberger, a forester who helps Northeast Kansas cities assess their conditions. “I made inventories where I went to burrow into a neighborhood, and as far as I could see, it was all oak.”

Bomberger works for the Kansas Forest Service.

She said that “the national conversation now is to reduce those numbers” of individual species or closely related trees that have been planted in certain areas. “We are trying to better guard against catastrophic losses.”

But it is difficult to get rid of this habit.

One woman called Bomberger, frustrated that her neighborhood charter had staked out ash trees before the Emerald ash borer showed up. Homeowners who encountered invasive beetles were bound by an ancient rule to replace their stricken trees with more.

The National Park Service raised some tree owners by surprise when it decided in 2013 to replace 800 ash-lined trails near the St. Louis Gateway Arch. With a new monoculture – 800 London Plane Trees. the agency said The consistency was impeccable to the historical character of the park.

The risks that come with overdoing any one type grow year by year.

Global trade is reshaping life on the planet at an unprecedented pace.

It transports organisms to faraway places where they escape many or all natural predators and find a buffet of appetizing plants ill-equipped with the evolutionary defenses that check their appetites back home.

This is when a beetle or fungus can transform from a balanced part of one place’s food web into a destructive invader of another.

Dutch elm disease appeared on our continent less than a century agodestroying street awnings and continually striking elms in natural areas.

A mushroom has been discovered from Asia Billions of chestnut trees in North America In just a few decades.

Beetles wipe out pine trees and thousands of cancers plague Colorado black walnuts. Aphid-like insects decimate great hemlock trees on the East Coast and in the Upper Midwest.

Scientists race to grow plants resistant to the new invaders, but these efforts take decades with no guaranteed success.

Nor does it prevent the massive economic and environmental losses that are taking place in the meantime.

Kevin Boyle, economist and director of Virginia Tech’s real estate division, studies trees from the perspective of property values.

He has studied the financial impact of large-scale tree-killing pests – incl Emerald ash borer in the Milwaukee area.

“When trees are damaged and die, it reduces the value of the property,” he said.

This financial loss multiplies the dollars realtors and public agencies are pouring into removing and replacing diseased trees.

The three types of diversity

From a purely financial perspective, trees are an investment.

Boyle and colleagues sifted through existing research and published A Dimensional analysis. The results indicate that a house in a neighborhood with a fiery tree costs about $3,250 less than a house in a neighborhood where the mature canopy covers about 30% of the land.

To protect their investment, many cities are taking an increasingly careful approach.

Although they generally can’t control what you plant in your garden, they often set rules for trees in the public right of way.

Forest experts recommend—and cities increasingly follow—three types of diversity in these areas.

1. Plant lots of different types.
2. Make sure that these types are sufficiently different. Imagine filling a town with a dozen species of oak and nothing else. All of these oak species are so closely related—part of a single oak genus—that a single threat can wreak havoc. So he planted different races.
3. Make sure that these races are sufficiently different. If you fill in a subsection with crab, hawthorn, cherry, and raspberry, you’ll get four different genera, but all within one family called rosacea. These distant relatives can still share a lot of vulnerabilities.

old rule is10-20-30. Ensure that no more than 30% of the trees planted in a community fall into any one family, no more than 20% fall into a single genus, and no more than 10% fall into a single species.

But Bomberger says many experts now recommend that cities push diversity even further, and she agrees.

Neighborhoods can have the best of both worlds: tree diversity and visual consistency, said Robert Whitman, landscape architect with Multistudio in Kansas City.

Central American Regional Council helped write Model Tree Ceremonies In 2020 cities could use them to protect the curtains that strengthen their tax rules, clean the air and mitigate street flooding.

“Diversity is very important,” he said. “But what I will say is, if every street has a consistent mix of genres falling on it, it’s less uniform. It looks a little less organized.”

Imagine instead switching genres from street to street. White bog oak lines one street, sycamore lines the next, and sugar maple lines the third. Some neighborhoods of Al Barari Village that were built in the 1940s followed this approach.

“You’re still building diversity into neighborhoods,” he said, “and there’s a clear identity between every street.”

This approach makes some foresters nervous.

“We can plant very diverse streetscapes that are still attractive,” Bomberger said. “It wouldn’t just be the ones we’ve all seen from American elms, who have that symmetry. Because in this day and age, why would we want to roll the dice for something to come and be a disaster on that street?”

native or non-native

A second debate in the field: Should we stop planting trees from far away?

Views differ because some experts are more concerned about maximizing diversity to hedge against pests, while others focus on the environmental downsides associated with non-native species.

“I prefer the natives,” Bomberger said, but “the people that I work with, the cities that I work with, we’re going to plant some non-native trees because what we’re trying to do is guard against catastrophic losses.”

Many cities like Overland ParkAnd Kansas City, Kansas, And Salinapromoting a mix of native species (bur oak, lily poplar) and non-native species (zelkova, ginkgo).

But an increasingly boisterous movement of scientists, environmentalists and passionate homeowners is promoting native species.

Some non-native trees do not support native wildlife, such as birds and butterflies. Others spread from the suburbs into the natural areas, where they suffocate the native plants that these organisms need to reproduce. Bradford pear Provides a prime example.

Whitman, at Multistudio, draws heavily on regional genres in his designs.

“I’ll look at my species choices,” he said, “and always choose a native if the native fits the bill.”

Whitman is not absolute and says he relies on non-native options if they fit the site’s conditions and design better.

But he argues that cities can grow enough diverse canopies using native species — and warns that some non-native options, such as ginkgo and zelkovas, have “nearly no benefit to the overall ecosystem.”

“It looks good in a neighborhood,” Whitman said. But they “do not contribute (to the food web). Literally, they are like plastic trees.”

Celia Lopes-Jepsen is the environment correspondent for the Kansas News Service. You can follow her on Twitter @celia_LJ or email her at celia (at) kcur (dot) org.

The Kansas News Service is a collaboration between KCUR, Kansas Public Radio, KMUW, and High Plains Public Radio that focuses on health, the social determinants of health, and their relationship to public policy.

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