RACE TO SAVE FOREST

Caitlin Looby

Milwaukee Journal Sentinel | USA TODAY NETWORK – WISCONSIN

Foresters work to preserve one of Northwoods’ most unique habitats

BAYFIELD COUNTY – On a drizzling, early fall day last year, Jason Holmes was checking in to see how newly planted bald cypress seedlings were faring in the county’s forested wetlands.

While Holmes was trudging from seedling to seedling, he noticed that some of the canopy trees no longer had leaves. The Bayfield County forester paused for a moment, and then it hit him: Only black ash trees had lost leaves. The others were fine. Holmes took a closer look at one tree and saw a D-shaped exit hole – a telltale sign that the emerald ash borer had eaten its way into the trunk.

“Son of a gun, that’s probably it,” Holmes recalled whispering to himself. It was the first time evidence of the jewel-colored beetle had been spotted on Bayfield’s county forest land.

The emerald ash borer is an invasive beetle that kills ash trees by eating the tissues underneath the bark. Since its introduction in 2002, the wood-boring beetle has rapidly spread across much of the U.S., killing tens of millions of ash trees along the way.

In Wisconsin, the invasive beetle was first found in Ozaukee County in 2008, which means it was likely in the state a few years earlier. Since then, it has hitchhiked its way north on firewood and lumber. As of this summer, it’s been found in every Wisconsin county.

The invasive beetle is expected to wipe out nearly all of Wisconsin’s white, green and black ash trees.

It’s already decimated ash tree populations in the southeastern part of the state. But northern counties, like Bayfield County, are the final frontier for the invasive insect, as its population is still low, Holmes said.

Foresters say the full impact won’t be realized for another five to 10 years, leaving a tight window to save one of the Northwoods’ most unique habitats: forested wetlands.

Forested wetlands, or swamps, only cover a fraction of county forest land, but if the ash trees go, the ecosystem will too.

Awaiting the imminent arrival of the invasive beetle, county foresters started to plant other kinds of trees — many of which were not found in the area — a few years back with the hope they would find one that can thrive in the cold, soggy system.

But the challenge is “no one has written the book on this yet,” said Holmes, inventory and analysis forester at Bayfield County Forestry and Parks.

As efforts to find a tree that will save the county’s forested wetlands ramp up, the foresters are in a race against the wood-boring beetle.

But no matter how successful they are, the fate of black ash is likely sealed and the forested wetlands will never look the same again.

Emerald ash borer may cause forested wetlands to ‘swamp out’

Bayfield County manages 178,000 acres of forest, which makes it the thirdlargest county forest in the state.

The county touches Lake Superior and straddles the continental divide that separates the Lake Superior and Mississippi River watersheds. This means the county’s forested wetlands are an important resource to help keep both major watersheds clean.

Forested wetlands are similar to other wetlands, Holmes said, but the black ash trees are bigger pumps that can help remove water and slow water down.

Wetlands are sponges that hang on to rain, suck it up and then release it slowly, which helps prevent areas from flooding and rivers from washing out. They also help filter out sediment, excess nutrients and pollutants before they head downstream.

Another benefit is that the trees provide shade that helps keep water cool for fish and other organisms, Holmes said.

The worst-case scenario is that the emerald ash borer will kill all the black ash and the wetlands will no longer be forested, said Caleb Brown, forester at Bayfield County Forestry and Parks.

Without the black ash, the water will no longer be sucked up and the sites will become wetter and wetter.

If this were to happen, it would be called “swamping out,” Brown said. The ecosystem — once filled with towering trees — would turn into a pond or a bog. That’s why Holmes, Brown and other county foresters are working to plant trees quickly before the system swamps out.

But there aren’t any other local trees that can grow in such wet sites, so “we’re looking for alternative species that can fill that role,” Brown said.

Keeping the borer at bay will be a career-long challenge

The emerald ash borer can be present in a stand of trees for years before people notice it.

“We are really behind the eight ball with (the emerald ash borer) relative to when it arrives in an area, when the symptoms appear and then when we document it,” said Paul Cigan, forest health specialist at the Wisconsin Department of Natural Resources.

It takes some time for the wood-boring beetles population to boom in an ash tree stand, Cigan said. Over time, ash trees will lose leaves and branches. Woodpecker flecks are another sign that the invasive beetle has infested a tree; the bird feeds on the beetles’ larvae.

About one third of the counties in Wisconsin have already lost more than 90% of their ash trees due to the emerald ash borer, according to Cigan.

Much of the destruction has been in the state’s southeastern counties, like Milwaukee, Waukesha and Dane counties, near where the emerald ash borer was first found, Cigan said.

There is no silver bullet to reducing the insect’s impact, but Bayfield County at least has an opportunity to get ahead of it by planting trees.

The foresters have tried silver maple, swamp white oak, hackberry, sycamore and bald cypress. So far, the swamp white oak and silver maple seem to be surviving the best, Holmes said. Both are found in southern Wisconsin but are rare up north.

The county is also using pheromone traps that attract the emerald ash borer so county foresters can know exactly where it is. Pheromones are chemicals similar to hormones that organisms use to communicate with each other.

And while they still have time to save the forested wetlands, Cigan said, it’s “misguided to think that ash will ever have the density that it does now in our lifetime.”

“We will see ash humbled,” Holmes said.

There are other tactics underway to keep the invasive species at bay so foresters can regenerate ash stands, like releasing wasps that feed on the beetle. Scientists are also investigating the ash trees that have survived an infestation — known as lingering ash — to see if they have a genetic advantage that could help, Cigan said.

And until a new tree can fill that niche in the forested wetlands, the future may need to be reimagined.

When it comes to forest management, this is “the biggest challenge of our careers,” Cigan said.

Caitlin Looby is a Report for America corps member who writes about the environment and the Great Lakes. Please consider supporting journalism that informs our democracy with a tax-deductible gift to this reporting effort at jsonline.com/RFA or by check made out to The GroundTruth Project with subject line Report for America Milwaukee Journal Sentinel Campaign. Address: The GroundTruth Project, Lockbox Services, 9450 SW Gemini Dr, PMB 46837, Beaverton, Oregon 97008-7105.