Protecting Minnesota's changing northern forests

For trees, northern Minnesota is something of a crossroads. The state's hardwood forests blend north into pine and birch, and then, in the northeast lakes area into cold climate species like aspen and jack pine.

Cold-tolerant trees are a signature feature of the Boundary Waters Canoe Area Wilderness and Voyageurs National Park. That is the southern stretch of the boreal forest, which continues north into Canada.

However, according to researchers with the Nature Conservancy, the northern forest could look a lot different in the coming decades, as warming temperatures push cold climate trees out.

Mark White has developed forest computer models to predict how things will change, and recently presented them at a wildlife research seminar in Duluth.

"What it tells us, at this point, is over the next 100 to 200 years, that a lot of the characteristic boreal forest species, like balsam fir, and black spruce, and white spruce and paper birch, are really going to decline dramatically, regardless of how we manage the forest," said White.

Imagine a Boundary Waters lake surrounded in the autumn by lush red maple, and golden oak. That's not a bad forest, but it's different than what we see in one of today's key tourist destinations. And, it will support a whole different set of other plants and forest animals than today.

White says climate change can put the forest at risk. The best defense, he said, is a diverse forest that mixes both different species and the ages of trees.

"Diversity in species and structure makes forests more healthy and resilient in the face of these many stresses, like increased droughts, and more insect pests and wildfire risks, and all of those things," said White.

That will be even more important with a climate that's predicted to be increasingly erratic, with prolonged hot or wet spells, and robust storm events -- like the 1999 blowdown storm in the Boundary Waters.

White said the changes could come rapidly, leaving a poor forest caught between cold-weather trees dying, and warm-tolerant trees still to move in.

White's computer models come with what he calls an ecological forest restoration scenario. It's a plan, White said, land managers can use to manage the forests to promote the best mix of trees. It can also predict how those trees will do in a warmer northern Minnesota.

"Attempting to manipulate the forest ... may entail some risks, as opposed to respecting nature and how nature itself adapts to changes that may come."

But it's a challenge to avoid that scenario. White said it could mean government and private landowners selecting the right species, managing with less clear-cutting and more tree thinning, and letting some trees grow longer. But White said the changes he recommended at least offer hope that northern Minnesota won't get caught between forests.

"This work shows that management is really going to be a valuable tool for trying to maintain these healthy, resilient landscapes, and maintain some of the character of the northern forests that ... we all value," said White.

Wayne Brandt, with the industry group Minnesota Forest Industries, says industry will adapt regardless of the tree species available. But Brandt thinks the forest will change naturally, and that it might not be a good idea to manipulate the forests on speculation of great changes coming.

"Attempting to manipulate the forest at this point in time -- to try and project out some changes that may or may not occur during different time frames -- may entail some risks, as opposed to respecting nature and how nature itself adapts to changes that may come in the future," said Brandt.

With that said, when changes come, Brandt said it's up to industry to figure out how to use what ever the forest grows.

But researcher Mark White said this period of climate change may be much more rapid than nature would ever provide. In that case, a little assistance from forest management might help keep a forest in northern Minnesota.

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