At St. Paul's Crosby Farm Park, see the future of Minnesota forests

ST. PAUL — At Crosby Farm Regional park, the forest of the future is appearing.

Emerald ash borer has killed nearly all of the ash trees in the park, leaving gaps in the canopy and creating hazards for visitors.

Cottonwood trees, which provide critical habitat for bald eagles and can consume up to 200 gallons of water a day, are struggling to regenerate.

And, like many other parts of the world, the park is seeing rising temperatures, longer and more intense flooding and new pests.

But work is underway to respond: The urban park is home to a 20-year study exploring how to adapt to the changing conditions.

It's part of the Adaptive Silviculture for Climate Change (ASCC) program, a network of 14 studies across the U.S. and Canada — three of them in Minnesota — that aim to help forest managers respond to the effects of climate change over the coming decades.

"It's a real change that we understand quite well, and we can't sit around and wait to see what happens," said Brian Palik, who leads a study site in the Chippewa National Forest in north-central Minnesota. "That's really the whole idea behind the ASCC network is to start showing people now what can be done to adapt."

Researchers are testing treatments to see what types of trees can survive and what management practices will help forests thrive into the future.

All ASCC sites have three treatment types — resistance, resilience and transition — that represent increasing levels of change, but what those treatments look like varies from site to site.

• Resistance plots reflect the current ecosystem, containing trees that already grow in the area and following existing forest management practices.
• Resilience plots include trees that are native to the study area but may have been sourced from more southern, slightly warmer areas.
• Transition plots attempt to prepare the forests for greater change by incorporating new species from farther south that are adapted to projected future conditions.

There are also control plots where no action is taken.

The study at Crosby Farm — overseen by the nonprofit Mississippi Park Connection (MPC) in partnership with local, state and federal agencies — started in 2020, when volunteers helped plant more than 1,000 trees across 24 plots.

Three years in, researchers are starting to see which species are thriving in this environment. These findings will help inform forest management in the Mississippi River National Recreation Area and other floodplain forests.

Native species such as disease-resistant American elm, swamp white oak and river birch have high survival rates, said Marcella Windmuller-Campione, one of the researchers on the project and an associate professor at the University of Minnesota. And even some more southern species, such as northern pecan and American sycamore, are doing well.

"We know that these trees, if they're healthy, will survive 100 or 200 years," said Anna Waugh, assistant director at the MPC. "So which trees and which species will have the most success in those conditions — that's really what we're studying."

'We're trying to generate useful information right now'

Meanwhile, another ASCC study is just getting started in the southeastern part of the state. The Driftless Area site spans Minnesota, Iowa and Wisconsin and covers land that is mostly privately owned, adding a layer of complexity to the study.

And hundreds of miles north in the Chippewa National Forest, the study Palik leads is already a decade in. It was the first site in the ASCC network and the largest climate adaptation study in the country when it was established, said Palik, a science leader for applied forest ecology with the U.S. Forest Service.

The study focuses on what Palik calls Great Lakes mixed-pine forest, a blend of species dominated by red pine that's found from northern Minnesota to northern Michigan and into Ontario.

Climate models show the area is becoming less and less hospitable to the majestic red or Norway pine, Minnesota's state tree. It's an important species ecologically and economically in the region, and it's under increasing stress as droughts become more severe and frequent.

And while the ASCC study there will last at least 20 years, waiting that long to act would put forest managers "behind the curve," Palik said.

"We're trying to generate useful information right now that can influence that," he said. "And it's meant to dictate what species we can be reasonably certain can do well in a warming climate."

Researchers are seeing encouraging results in the first 10 years of the study.

They're monitoring how native trees perform with existing management practices such as thinning, or removing every third tree. The remaining trees have been found to do better after drought because they get more moisture from the soil.

And researchers have found that Minnesota's climate is already suited to species from farther south.

Trees from southern Minnesota, such as white oak and bitternut hickory, have nearly a 100% survival rate, and species from even farther south, such as bur oak from northern Illinois, are also doing well.

Bringing non-native trees into an area isn't without risks. There's potential for a species to become invasive or bring new pests to an area. But those involved in the study say they're helping along a process that would happen naturally over time anyway.

"We're not bringing something from Florida here and planting it — I'd be a little concerned about that," said Palik. "We're bringing species that probably — if we didn't have roads and parking lots and agricultural fields and we still had passenger pigeons — would already be here. So we're just helping them get that jump, you know, 200 miles north, and getting them established here."

"Our goal is to keep forest on the landscape," he added. "And it may look different than what it used to, but we're still focused on trying to keep what people want, which is a forested ecosystem in that part of the state."

'Just the beginning'

While the ASCC studies are intended to inform future forest management, those involved also stressed the importance of educating the public.

The main way for people to get involved at Crosby Farm is through hands-on volunteering, Waugh said. Volunteers organized by the MPC — dubbed the "Crosby Crew" — assist with plot maintenance and data collection from spring through fall.

This year, their season was delayed by spring flooding at the park, and the MPC has had to cancel several events due to heat and poor air quality. But on a recent Saturday, clear conditions meant a small group gathered at the park to help out.

They spent the morning repairing fences that had been knocked down by a fallen tree, then moved on to removing burdock and thistle while cyclists, dog walkers and runners passed by on the trails nearby.

This level of visibility isn't possible at some other sites, Waugh said, and is one of the unique aspects of the study at Crosby Farm, which was the first urban site in the ASCC network.

"I think that this experiment is really just the beginning of the education that can happen on this site," she said.

Lisa Bain is a former Star Tribune editor and a Crosby Crew volunteer.

Get involved

Sign up to volunteer with the Crosby Crew at parkconnection.org/volunteer.