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Tracking invasive species in Detroit, one tree at a time

Meg Cramer
Ecological surveyor Chris Kort leans back to get a better view of a tree he's cataloging. Kort has counted over 13,000 trees in Detroit since March.

There’s so much to know about what’s happening in the world around us, and that information gives us insights into patterns and changes that could have a big impact on our lives.

But finding these trends requires a lot of data – and somebody has to go out and get it.

Chris Kort is one of those people. He's an ecological surveyor counting trees in Detroit. For every tree he counts, Kort marks where the tree is, then he adds details like its size, species, and health.

Kort does this all day long, walking up and down Detroit streets, counting trees on city property.

“Since March, I have surveyed 13,468 trees. And counting,” he says.

The data from this survey will go to the city, the state, and scientists at the U.S. Forest Service. It will tell a story about what’s happening to trees in the city.

A database like this has to be built manually by people like Chris Kort, tree by tree.

Kort is like the human version of the Google street view car, roving up and down blocks and adding to his map. He notices details that most people miss. There are some things you can only find on foot. 

“I’ve actually been collecting pennies on the sides of the roads for, like four months," says Kort, "I cashed in 2,200 pennies yesterday. People just don’t pick them up anymore apparently.”

Mostly, researchers are trying to nail down the basics about Detroit's urban forest, like what kinds of trees are in the city, and how many there are.

But they’re also testing a new survey method, a survey that measures damage caused by invasive species.

That’s because Detroit is where the Emerald Ash Borer was first discovered back in 2002. It probably arrived in the wood of untreated shipping palettes. Now, it’s all over the Midwest. The insect infests and kills Ash trees.

“I would say we’ve surveyed maybe 8,000 ash trees since I’ve been here. Every single one of them is dead or dying,” Kort says.

Kort is a surveyor for Davey Resource Group. The company worked with the U.S. Forest Service to develop the Insect Pest Detection protocol. The Detroit tree inventory is the first time it’s being used.

Following the protocol, surveyors like Chris Kort note damage from all kinds of things – including invasive species.

Researchers will unpack that data to identify new trends and learn more about old ones, like how the Emerald Ash Borer spread through the city and beyond.

Chris Kort shows me some of the symptoms he’s looking for on a dying ash tree. First, there’s the hole where the insect crawled out, it’s shaped like an upper case “D," and the galleries, grooved doodles on the trunk left by the bug as it moves around behind the bark.

He says the infestation is about five years along. It's obvious on trees like this one that the Emerald Ash Borer has taken hold, but in its early stages the symptoms of an infestation are not as noticeable. 

One of the goals of the new pest detection protocol is to learn more about invasions at all stages so that researchers and communities can do a better job finding them before they get this far along.

The scale of a project like this is overwhelming. How can you keep an invasive species like the Emerald Ash Borer in check when there are so many potential hosts?

David Nowak is a project leader with the U.S. Forest service. He says that urban forests have millions of trees, but they also have millions of people.

"The people, if they’re educated, can start looking at some of these things, they can be detectives – if you will – or detectors of these insects and diseases when they come in, and maybe provide that information to experts to help determine what’s happening.”

Once the Detroit database is set up, it can be monitored and updated by people in the community.

The hope is that this relationship between communities and researchers will mean a quicker response for groups that are trying to keep invasive species in check.

This story was informed by the Public Insight Network.

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