See more of the story

The closure of the Verso Corp. paper mill in Duluth this summer came with an economic hit to northern Minnesota — and foresters are now worried it also puts thousands of acres of trees at risk of wildfire.

The mill was one of the area's biggest buyers of spruce and balsam fir trees. Loggers who planned on harvesting the trees suddenly found themselves with nowhere to take them. With little logging demand, both public and private forest managers now have to leave the trees standing.

That wouldn't be too big of a problem under normal circumstances, said Jason Meyer, deputy director of St. Louis County's land and minerals department. But Minnesota is in the midst of a prolonged outbreak of spruce budworm, a pest and caterpillar that has killed more than 200,000 acres of fir and spruce trees in each of the last three years.

"Without an outlet, all that balsam fir and spruce that would have been utilized is being left in the woods," Meyer said. "Couple that with the budworm outbreak and you're left with these thick stands of dead, dying and drying out trees. It creates more of a fire hazard."

Verso closed the mill in June, saying the decision was driven by the COVID-19 pandemic, putting 235 people out of work. The mill made nearly 300,000 tons of paper a year and bought a great deal of spruce and balsam fir trees to do it.

Aside from pulp, there are few industrial uses for spruce or fir. Some places will saw the highest quality trees into boards, but the majority of demand comes from paper makers, Meyer said.

While there are large paper mills in International Falls, Grand Rapids and other parts of the state, the cost to ship major quantities of timber makes it unprofitable for most loggers near Duluth or farther up the Arrowhead in Lake County to try to sell it there.

St. Louis County, which manages vast acres of public forest, stands to lose tens of thousands of dollars worth of unsold fir and spruce this winter because of the closure of the mill, Meyer said. More than a thousand acres of the trees could remain uncut.

The big question is what foresters will do with those trees as they fall to the budworm outbreak, he said.

"In some cases it might be felled and laid flat on the ground where it can rot fairly quickly, or in some cases it'll stay standing," he said. "There might be a central location to take the trees for future burning."

The insect wreaking havoc on spruce and fir is native to Minnesota and is found just about everywhere the trees are.

The budworm's population naturally booms and busts somewhere in the state about every 12 years, said Eric Otto, forest health specialist for the Minnesota Department of Natural Resources (DNR). Spruce trees are able to survive longer than balsam fir when outbreaks do happen, he said, but both eventually die when there are enough of the bugs to stress them.

Every spring, the caterpillar emerges from its cocoon-like shelter and eats the newest needles on the tree.

"They usually don't eat the whole needle so you can see the tops of the trees get a scorched appearance with all these dead brown needles," he said.

After a few years of heavy feeding, the trees starve because they don't have enough needles to collect energy from the sun.

The budworm outbreaks follow their food, Otto said. As the bugs eat themselves out of one area, they can slowly spread to another until eventually too many trees are stripped bare and the budworm's population plummets. Young trees then start to grow back and the cycle begins again.

The latest outbreak began in 2018, spreading from eastern St. Louis County to Lake County and into Cook County. Aerial surveys showed more than 200,000 trees were killed by the budworm in 2018 and 2019. The DNR estimates that up to 300,000 trees were killed this year.

Forest management

Verso's Duluth location made it a great outlet for spruce and fir loggers along much of Minnesota's North Shore, and the loss will certainly have an impact on the forests there, said Jon Drimel, timber program supervisor for the DNR.

The DNR, the U.S. Forest Service and individual counties all work together to remove swaths of dead trees that become fire hazards, Drimel said.

Because the spruce budworm will likely always be present, the best long-term treatment is to build up a diverse forest with more species that won't fall to any one pest, he said. Trees that are already stressed are hit the hardest when there are outbreaks.

"The best thing for us now, would be if we could get a lot of rain and good snow cover to keep the trees alive and healthy," Drimel said. "If we can get a good winter with nice frozen ground, it will help loggers get out and manage these stands."

Greg Stanley • 612-673-4882