How Minnesotans are helping trees in the north woods adapt to climate change

Photo Credit

Nora Hertel, St. Cloud Times

This story by ESI Journalism Fellow Nora Hertel was originally published for The St. Cloud Times, where it appears with additional photos and resources.
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By Nora Hertel

DULUTH — Julie Etterson pursued a central question throughout her career: Can plants evolve fast enough to keep up with the pace of climate change?

She found that they cannot.

Etterson, a biology professor and department head at the University of Minnesota-Duluth, came to that conclusion after more than two decades of research.

Now she and a slew of partners are in the midst of a project that could help Minnesota's north woods adapt more quickly to climate change.

They took seeds from southern Minnesota trees, recruited farmers to help them grow and will plant the seedlings in the northeastern part of the state where climate change has already slowed the regeneration of some iconic tree species.

It is called the Forest Assisted Migration Project. And it has drawn national attention. It's a somewhat controversial strategy, influencing a forest's gene pool.

"A lot of papers came out about it at the same time: It's good. It's bad. I hate it. I love it," Etterson said in her Duluth office in July. "They just don't agree, and I would say they still don't agree to this day. As the consequences of climate change become increasingly evident on the landscape, I think people are warming up to the idea more than they ever have before. Because something has to be done."

Minnesota temperatures have increased between 1 degree and 3 degrees Fahrenheit in the last several decades, with a faster increase in the northern part of the state. If climate change continues unchecked, much of Minnesota's forests could change to open prairie by the end of the century.

As threats from climate change loom, organizations like The Nature Conservancy and the Minnesota Department of Natural Resources are looking to plant more trees and alter forestry and agriculture practices to draw more carbon dioxide from the atmosphere and deposit it into plants and the soil where damage from the greenhouse gas is limited. Plants do that naturally through the process called photosynthesis.

"A tree can only sequester carbon if it survives. And right now, the boreal constituents of the North Shore forests are not surviving," Etterson said. Many are dying and not regenerating. Even the most common aspen species are not prepping their next generation as they used to.

Boreal forests are home to moose and many coniferous trees and are known for long and snowy winters.

The Nature Conservancy has worked with Etterson on the assisted migration project for years and will be one of the biggest buyers of seedlings next year. The University of Minnesota Duluth planted 825 seedlings into a research plot in September.

Roughly 50,000 other seedlings will go out in the spring. Buyers include three Soil and Water Conservation Districts, Minnesota Power, Rajala Woods Foundation and The Nature Conservancy.

Working with 'forest people'

Cree and Jason Bradley started with 27,000 yellow birch seeds, 12,000 white pine seeds and 7,000 red oaks. The two also raise vegetables and produce maple syrup on their Two Harbors farm.

"We've always been forest people, and we love to grow things," said Cree Bradley. "You take that combination — and the thought of growing trees for a healthy forest — it so matches who we are."

Cree expects to make more money off the red oaks, but the white pine and yellow birch mean more to her and Jason. They do some work in the Superior National Forest and love pine species.

"When we think about climate change, this boreal forest is really going to change. And it's going to be changing to this more deciduous, red oak forest. And we're playing a role in that. There's a little bit of sadness there for us to be real honest," Cree said. "Change is hard, especially when it's something like climate change."

The Bradleys' farm is among 15 raising seedlings for the assisted migration project. All the participants share a fondness for trees, including David Abazs, the northeast Clean Energy Resource Teams coordinator, who has worked with the producers in the project and raised some seedlings at the Finland farm he runs with his wife.

"I think there's a real synergy happening with the U.S. Forest Service, with the DNR, with the nonprofits like The Nature Conservancy and even for-profit energy companies like Minnesota Power," Abazs said.

Ten years ago, only local seeds were used for reforestation efforts, he said. But Etterson's research has shown the importance of southern genetics.

"All of those things put together, I think make it very promising, but we'll see if they have the duration that's going to be needed," Abazs said. "It's got to be a whole infrastructure and building up of our capacity to assist the forest and make the forest more resilient and strong."

Growers started with nearly 400,000 seeds and acorns from the southern half of the state and almost all of them were distributed and planted with a goal of producing 85,000 seedlings.

Abazs estimates 50,000 will make it to the spring. Plans are underway to produce another 85,000 seedlings with producers building on knowledge they gained this year.

Growing new pillars of the north

It has been a difficult growing season in 2021 with trouble from chipmunks, severe drought, a late freeze and other challenges, Abazs said.

Some of the seeds had very low germination rates, and farmers had to plant several seeds to get one seedling.

The goal was for farmers to break even, but Abazs expects many to lose money this year.

The Bradleys signed on knowing that they might not succeed, Cree said. They invested a lot of money in equipment, including special containers for the seedlings. And it's been a learning process for all the farmers in the program.

"We had to be willing to know that we might not succeed at this. And we might need to spend a lot of money and be OK if we don't succeed on it. That's just part of the risk with farming," she said. "But if we are successful at it, which we want to be and hope to be, it is an enterprise that we felt like we could generate income from."

Abazs hopes that the program will be self-sustaining, that farmers can continue to raise seedlings and have buyers for that crop.

"We don't want this project to be dependent on grants," he said. "We want the core fundamentals to work within the economic system."

There is a shortage of seedlings across Minnesota and the U.S. as communities work to replant after forest fires and seek to increase tree populations as a natural climate solution.

Forests can help reduce the effects of climate change, because they take carbon dioxide from the air and store it in plant material and the soil. And while trees are touted by many as a useful solution to climate change they cannot counterbalance the effect of all the fossil fuels humans have burned. So reforestation has to go hand in hand with reduction of greenhouse gas emissions.

The Forest Assisted Migration Project works to help forested land adapt to the climate change that has already happened. And it will add to the total number of trees growing in Minnesota — a goal The Nature Conservancy pursues through several initiatives.

One effort called Conifer Strongholds planted 100,000 conifers in cooler pockets of northeastern Minnesota where they're likely to continue to grow despite increasing temperatures overall.

Meredith Cornett, climate change director at The Nature Conservancy, has worked on the project with Etterson since its inception. She found it serendipitous that the white pine, which is featured in the assisted migration project, is expected to do well within climate change. They were targeted in Minnesota's logging heyday in the late 1800s and early 1900s.

White pines are also a favorite of Matthew Jahnke, the greenhouse manager at the University of Minnesota-Duluth. He helped raise the seedlings that are now planted at the university's research farm.

"White pine are the pillars of the north. They're the largest tree that we have," Jahnke said. "They grow really slowly."

From talk to assisted migration

Minnesota's forests are important to the state's identity. They're central to the tourism and timber industries, Etterson said. And they're important for wildlife and water flow.

As Etterson learned from her experiments that adaptive evolution was too slow to keep up with climate change, she started to think about how to help local plants transition.

There's a long history of forest managers selecting species or seedlings with different genetic traits within the same species to accommodate the environment, Etterson said. And the concept of assisted migration took shape within the last 15 or 20 years. She was among a group of scholars in different disciplines that published a number of papers on it.

Etterson has looked at data from 160-year-old forestry trials and studies of assisted migration to expand the species distribution of butterflies in England. There's evidence to support assisted migration, but the studies weren't local and weren't about trees, she said.

"I personally felt like it was getting to the point in the scientific community where talk was cheap. People are talk, talk, talk, talk, talking about assisted migration," Etterson said. "But where we were really lacking was empirical data. Somebody saying, 'Let's try this and see if it works.'"

Now Etterson and her partners are trying it in Minnesota's forests to see how it works. She and her students will track how the trees perform — how fast they grow and how much sugar they produce from photosynthesis.

They have reduced some risk by keeping tree species in their normal growing range and moving them in line with the climate change that has already occurred, she said.

"My goal is to retain healthy forests. And I'm a biologist, so I tend to think about the value of those forests from the perspective of ecosystem services, clean water, shade, carbon sequestration, habitat for other organisms," Etterson said. "And of course, the enjoyment of the people who are up and down the North Shore all summer long. That's what really motivates me."