COLUMBIA — After riffling through the trunk of his car, Chad Herwald pulls out a device and explains it is a tangent height gauge.
He levels it in front of his face and gazes up, determining what arborists call "the strike zone."
"I can look at that thing and think ..."
Herwald shuffles around, keeping the gauge level and his eyes trained on the top of the tree.
"... it's gonna miss me right here."
Years of experience as a forester allow him to know when trees have become a hazard. His first inspection of the day is a pin oak on Pershing Road, reported by neighbors for its precarious lean and looking mostly dead.
By now he's standing in the middle of the road. He marks the spot at his feet and measures the distance to the base of the tree.
The angle on the gauge and some quick trigonometry tell him the tree is approximately 70 feet tall — tall enough, if it fell over, to give the owner of the nearest house at least a good scare, and certainly robust enough to crumple the fence just along the other side of the road.
The car parked underneath it wouldn’t stand a chance.
Herwald is Columbia’s city arborist, and part of his job involves fielding complaints about trees that may be dead or dying, like the pin oak he's currently evaluating.
“Basically, when I look at it, I see a hazardous tree that has lived its life,” says Herwald, who has been with the city for 10 years, eight as a forester and two as an arborist.
“The thing people need to realize is that not every tree lives to be 300 to 400 years old like the McBaine bur oak, which is surrounded by farm fields; not idling cars, concrete, houses, kids and peoples’ lawns,” Herwald says.
At first glance, the tree looks scraggly, diseased and, in some places, already dead. Broken branches hang precariously, and much of the foliage has died on its limbs.
The tree was planted in a neighborhood median, and beneath one especially dead side, the ground is littered with fallen branches.
“When a tree gets older, it gets weaker. Its own defense mechanisms are weaker,” Herwald says. “And then fungus starts to move in; insects start to move in.”
At this point, the pin oak is rife with both.
Maroon stains, like gashes, run down the tree at eye level. The tree is responding to the presence of some disease by attempting to “bleed” it out through sap excretion.
“If you see that kind of streaking higher up, that means the disease is throughout the whole tree,” Herwald says.
He cranes his neck and scans with his binoculars along the upper branches.
“Yep, see, it’s up there.” He points out the streaking, but also notices another fungus — a light grey mat of hypoxylon has already established itself on several branches. This, he said, is typically the “first responder” to a tree that is dead or dying.
He crouches down, and from his belt, pulls out something resembling both a hand shovel and a hunting knife, which he uses to poke around near the base of the trunk, where a neighbor has spread lawn clippings.
“Old grass clippings and mulch piled on the root flare (volcano mulching) don’t really do the tree any favors,” he said. He reaches down and gently lifts out tiny feeder roots that have poked into the new soil.
Trees have to be fed deep, Herwald says, otherwise they’re vulnerable to pests and surface chemicals girdling roots.
He notes that tree roots can often extend outward two to three times the radius of the canopy, which would make this tree vulnerable to chemical lawn treatments being applied on either side of it.
“People weed their lawns with herbicides targeting broad-leaf plants,” he says. “This is a broad-leaf, too. So what kills a dandelion can also kill a tree.”
Granted, it would take much more herbicide to fell a large pin oak, but over time, chemicals can accumulate and visibly stress trees even as large as this one. He says chemical damage is fairly common on trees found in heavily landscaped neighborhoods.
“You could keep what’s green on it green if you sat and put insecticides and fertilizers and fungicides on it,” he says. “But at this point, I see a tree that’s 50 to 60 percent dead already."
He already knows taking it down will be a contract job; a crew will first “top” it by removing larger and larger branches from the outside in, until all that’s left is a single spire to be segmented from the top down.
There's reason to save just 40 percent of a hazardous tree, he says.
“Tree mitigation” is just one part of his job as an arborist. He operates out of the city’s Community Development Department. As well as conducting tree inspections and preservation efforts, he works with engineers and city inspectors to approve landscape plans for commercial construction projects.
By the city’s land preservation ordinance, contractors have to meet strict requirements:
- Fifteen percent of a developed site must be landscaped, and 25 percent of climax forest must stay protected.
- If a 50-foot paved area runs closer than 20 feet to a public right of way, at least 50 percent of it must include a six-foot-wide landscape buffer.
- Landscaping must include one tree for every 4,500 square feet of pavement.
- Trees must meet size, species and longevity requirements, overseen by the city arborist.
“The only thing we tell them they can’t plant is Bradford pears, because they’re very invasive,” Herwald said. “Also, the big scare right now is emerald ash borer, so we’re pushing people away from ash right now.”
Herwald is in the process of compiling a list of trees that do well in Columbia’s urban environment, which would serve as a a landscaping resource on the city’s website. When he makes recommendations, though, he always pushes for variety.
“We’re trying to get away from that monoculture,” he said.
The growing type
On his small acreage north of Columbia, he cultivates a neat orchard of 12 apple trees and 12 pear trees in cultivars of three. He also maintains two large gardens, which he brags are almost yielding more blackberries and strawberries than he can handle.
"I grow shiitake mushrooms on the side," he said. “Basically, everything you'd expect an arborist to have.”
But he didn't always live on 10 acres.
Herwald studied plant and forest pathology in his home state at the University of Wisconsin. There, he and his roommates lived in a small apartment, appropriately situated above a floral shop. One of their hobbies was to take 55-gallon drums, cut them in half, fill them with soil and mount them on a flat spot as rooftop gardens.
He said it was then that got him thinking about what he really wanted to grow; plants that yield and have trade value.
"Tomatoes are phenomenal,” he said, “but everyone already does tomatoes. I always look for something that's going to be unusual and useful for trading. 'Hey, you've got chickens; I want eggs. Here's some strawberries.'"
After graduating, and a five-year stint with Foothills Parks and Recreation in Colorado, Herwald moved to Missouri with his wife, Deanna, and started as an assistant forester with Columbia Parks and Recreation. There he developed the philosophy that monoculture is not only boring, but perilous.
"When I started at (Columbia) Parks and Rec eight years ago, their plan was to monoculture the downtown streets,” Herwald said. “Elms down Ninth Street, bald cypress down Walnut, all cherries down Cherry Street."
From a sustainability perspective, he says, that isn't the healthiest practice.
Lining a street with the same species of tree is like stacking dominoes, according to Herwald. One disease or one insect, and in quick succession, trees can fall ill and even die. It would be tragic and unsightly, but it would also put a maintenance and fiscal burden on the city.
“The American elm is a classic example of what not to do in an urban environment,” Herwald said. “Everyone loved the American elm because they went up and arched over and typically didn’t destroy the infrastructure. Well, where’d that get you?”
His answer: a bunch of dead stumps.
American elms have experienced massive die-offs across the U.S. from Dutch elm disease, a fungus that arrived in North America in the 1920s. Its spread has been slow but catastrophic, and is still a conservation issue.
In the 1960s, Kansas City saw one of the worst mass tree kills in the Midwest. The city had exclusively chosen American elms to plant along its thoroughfares, which made it too easy for one infected tree to spawn an epidemic. An estimated 70,000 trees had to be cut down.
Herwald said one of the advantages of having a diverse forest is the ecosystem doesn’t depend on one tree to do everything. Urban trees should follow the same principle, he says, even if their role is simply aesthetic.
"There is no 'one-tree-does-it-all,' and we're foolish to think that," he said. "I personally would like to see an urban environment with no more than 25 percent of one species.”
A tree survey that recently took place in Columbia is the first step in maintaining that standard.
Earlier this spring, the Columbia Public Works Department received a $10,000 grant from the Missouri Department of Conservation, as well as a 5 percent boost on top of its annual budget from the City of Columbia, to inventory trees in the public right-of-way. He designated an area encompassed by Stadium Boulevard, Broadway and Providence Road to be surveyed, contracting the work to an accredited plant management and consulting firm based in Ohio.
In May, specialists from Davey Tree Expert Co. cataloged 2,356 trees across 91 different species, data Herwald can now use to extrapolate the tree numbers for other urban areas in Columbia.
“Everyone says we should have a ‘forestry management plan,’” Herwald explains. “Well, you can’t have a plan until you know what’s out there.”
From a conservation perspective, Herwald says understanding species distribution in an area prone to extreme weather and pestilence is invaluable.
“Now I’ve got a tree inventory that I can access online (that can) highlight all my ash and know exactly where they are, what size and in what condition,” he says. “It lets me decide which ones are likely to be affected first, which ones we’re gonna take out and which ones we’re going to try to save.”
The inventory also allows the city to direct maintenance efforts to neighborhoods most affected by bouts of disease or insects.
First though, Herwald wants to know which trees are hazards to people or property. From the survey, 142 trees are listed for removal, citing reasons ranging from poor structure to disease or insect infestation.
"It has to be done," he said. “The means for that survey to help us have a healthier urban forestry is monumental.”
It's unfortunate, he says, that he's often met with criticism for his management practices and painted as a sort of tree-hating, chainsaw-wielding despot.
Herwald emphasizes education and smart planting in his work, which is what he says it takes to manage Columbia's urban and climax forests. Community efforts led by Herwald, like a project last year on Scott Boulevard, have helped offset the costs involved.
"There was some mitigation they had to do there for storm water," Herwald recounts. "I picked the trees and bushes; I coordinated the volunteers; I showed them how to plant them, and then I'll go back in three to five years to make sure we have our survivability rate."
“I get a lot of satisfaction out of it because I’m showing these kids how to correctly plant trees for the future,” he said. "I just like educating people when I can."
Over the years, Herwald estimates he's planted trees in the thousands, having turned many Wisconsin hay fields into groves of healthy, growing trees he can bask under and be proud of.
“Three or four years ago I took (my daughter) back there, and what was once a farm field is now a forest. And, considering that was 14 or 15 years ago, it’s a big forest. So, when I say I like to watch things grow…”
His daughter, Lily, is 7 years old.
“I really enjoy the fact that I plant stuff, and in five or 10 years it’s going to make a difference.”
“It takes time. But they don’t grow if you don’t plant them.”
Supervising editor is John Schneller.