As emerald ash borer spreads, cities can't plant trees fast enough

Jennifer Thomas greeted the work crew outside her house with an unusual request: Before they cut down three ash trees on Syndicate Street in St. Paul, could they take down the squirrel nests and give them to her?

The St. Paul Parks and Recreation workers obliged. The gesture moved her, Thomas said. She wept when the trees came down.

"This is really devastating for us," she said. "It looks so stark."

Nearly 10 years after emerald ash borer was discovered in St. Paul's St. Anthony Park neighborhood, the invasive beetles have infested virtually every part of the city. The Parks and Recreation Department has dedicated millions of dollars to removing and replacing ash trees on a one-to-one basis. But it takes at least a year to replace a tree after it's been cut down and the stump ground up, so replanting has yet to catch up with the loss of thousands of ash trees.

"We're temporarily going to have less canopy — there's no doubt about it," said Parks and Recreation Director Mike Hahm. "We're responding to a disaster."

Between 2013 and 2017, St. Paul removed more than 17,000 trees, including nearly 6,000 ash trees. The city planted about 13,000 trees during that time.

Minneapolis has planted nearly 41,000 trees during that period, but it's still about a thousand fewer than it lost.

Though the two cities started with different approaches — St. Paul treated some trees with insecticides, while Minneapolis went straight for the chainsaw — both cities are now cutting down dying ash trees as fast as they can. St. Paul has dedicated a portion of its parks budget for emerald ash borer, and Minneapolis levies a property tax.

"Our whole sort of philosophy is that all the public ash trees are pretty much doomed anyway," said Ralph Sievert, director of forestry for Minneapolis Park and Recreation Board. "But if you wait too long, you could have them all dying within a short amount of time and then you can't keep up with getting all the removals done."

St. Paul had about 26,000 ash trees on city streets in 2009, the year that emerald ash borer was discovered — the first time the beetle was documented in the state. The city has since removed nearly 11,000 ash trees.

In the beginning, St. Paul kept ahead of the infestation by cutting down some trees that weren't yet showing signs of infestation, said Rachel Coyle, an urban forester with the parks department. But by 2016, the beetles had spread so much that crews started focusing on just cutting down ashes where they had been found, she said.

"Since about then, I'd say we've fallen a bit behind on removal of infested trees," Coyle said.

Ash tree removals in St. Paul are typically planned a year out. Crews aim to cut down trees in winter or early spring, remove the stump within six months and try to plant a new tree within a year.

But the whole process, which costs the city about $1,200 a tree, doesn't always happen that fast. If a resident calls about a dead ash tree on their boulevard, the city will remove it but usually won't replant until the area is scheduled for tree planting. If construction is planned on a street with ash trees, the city won't plant replacements until the construction is done. The lag time could be years.

Minneapolis has taken a similar approach, but also tracks and removes trees on private property. The loss of those ash trees, which make up the bulk of the urban canopy, is a major threat because property owners might not replace them, said Kevin McDonald, a supervisor in the resource management and assistance division at the Minnesota Pollution Control Agency.

McDonald worked on a 2015 MPCA report on St. Paul's emerald ash borer plan that recommended the city plant two trees for every tree removed. When a mature tree is cut down, McDonald said, it eliminates all of the "services" that tree provided — from reducing air pollution to cooling the urban heat island.

"Those are hard to replace when a 30- or 40-year-old tree is cut down and then a stick gets put in the ground," he said. "It takes 20 or 30 years for that canopy to grow back again."

Cities are still removing ash trees in Michigan, where in 2002 the emerald ash borer made its first appearance in the United States. Many would like to replace trees on a one-to-one basis, said Kevin Sayers, urban forestry program coordinator for the Michigan Department of Natural Resources, but doing that has become more difficult since U.S. Forest Service funds available early in the infestation dried up.

"The reality is, it's not always achievable," he said.

The St. Paul parks department's emerald ash borer budget grew from about $770,000 in 2011 to more than $2 million in 2017. Every year, the department looks for one-time funding sources — this year, it was a nearly $1.5 million grant from the Minnesota DNR.

In early 2017, the city decided to devote most of its emerald ash borer resources to removing infested trees, rather than to replanting. When residents complained about deforested neighborhoods, the city drew from its capital improvement budget to remove stumps and plant trees.

The city's 2017 Emerald Ash Borer Management Program annual report emphasized that was a temporary solution, and warned that replanting might again fall behind the urgency of cutting down infested ashes.

"If so, this will unfortunately lead to streets devoid of trees on an indefinite basis," the report said.

Parks officials say they recognize how important trees are to residents — and they're still aiming to replace every ash tree.

"To the individual property owner, it is their tree," Hahm said.

Within hours on Wednesday, the ash trees lining a block of Juno Avenue in St. Paul had become stumps. With all the shade suddenly gone, the sun beat down on pavement littered with woodchips.

Joan Powers stood outside her bungalow and watched the crew at work. It seemed inevitable, she said — and she figured that, in time, the city will replant the trees.

"It's sad," Powers said, as she planned to count the rings on the largest stump.

Emma Nelson • 612-673-4509