By Dan Kraker

MPR News, 90.1 FM

Minnesota’s iconic northern forests are undergoing a gradual shift as the climate warms. Aspen, birch, balsam fir and black spruce, for example, are projected largely to vanish from the state by the end of the century.

But some foresters are suggesting a more radical shift in approaching what to do about it. Although not everyone agrees, some in forestry are stressing urgency and experimenting with bringing new species from hundreds of miles away, betting that with a helping hand those trees stand a better chance of producing a healthy diverse forest than existing species.

For proponents, bringing oaks and even ponderosa pines from as far away as the Black Hills is the best way to ensure Minnesota and its sizable forest industry will have thriving forests many decades from now. Others worry that the idea is too much of a gamble and could wind up essentially introducing troublesome invasive species.

One place to see this approach in action is a recently logged clearing north of Two Harbors in the Superior National Forest.

Ecologists with The Nature Conservancy have planted 108,000 seedlings on 2,000 acres here and elsewhere in northern Minnesota. Last fall, in a forest of spruce, fir, birch and aspen, Mark White, a forest ecologist with the group, and Laura Kavajecz, a University of Minnesota-Duluth graduate student, were monitoring oak, white pine and basswood seedlings.

“We’re measuring the total height of each tree, the diameter and then the distance to the bud scale scar, so we can get at how much it’s grown this season,” Kavajecz said.

In that particular plot, White said, trees were growing from seeds taken from areas south and west of the forest about 200 miles away.

“These trees may have some characteristics that make them better suited to these sites in a warmer, drier future.”

A few of the seedlings came from even farther away – white pines from the lower peninsula of Michigan.

This represents a big change in the forestry world, where the longstanding practice has been to plant only local trees. But models predict in the next several decades those trees that have flourished here for centuries likely won’t be able to survive in great numbers.

Minnesota is unique because it lies at the convergence of three distinct ecosystems, or biomes. And the boundaries among those three – boreal forests of spruce, fir, pine and birch; deciduous forests of maple and oak and basswood; and prairie grasslands – are very sensitive to climate changes, said Lee Frelich, the director of the University of Minnesota Center for Forest Ecology.

In addition, Minnesota has been warming faster than most other states. In particular, northern Minnesota is heating up faster still – by nearly three degrees over the past century.

“So we can expect the boreal forest with a business as usual climate scenario for CO2, for example, to virtually disappear from Minnesota,” Frelich said.

Although he and others believe boreal trees will hang on in pockets of the state, he has already documented some deciduous species, like red maple, invading patches of boreal forest.