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ARTICLES
Dr. Lee Frelich foresees Ecological Perfect Storm
Cataclysmic changes approach northern forests
By Steve Foss
Timberjay
April 10, 2006
If the global climate change doesn’t transform the northern forests into something we don’t recognize, the invasive species will.
That was the simple but dramatic message delivered by Dr. Lee Frelich to about 100 guests at the 2006 Sigurd Olson Lecture at Vermilion Community College late last week.
Frelich is director of the University of Minnesota Center for Hardwood Ecology, and last Thursday he delved into the changes confronting the northern Minnesota forest from global warming and a variety of invasive insect and fungus species.
Frelich believes the forest will be transormed within the next 100 years or so.
The weather
The question, according to Frelich, isn’t whether the earth’s climate will continue to warm, but whether northeastern Minnesota will become warmer and drier or warmer and wetter than it is now.
If the climate dries, the region can expect a rapid evolution toward oak savannah like that seen in portions of central Minnesota. Warm and wet, he said, would change the ecosytem to one dominated by hemlock, oak and maple, with white pine as well.
He said such warming likely will push cool-weather species of trees, such as black spruce, north out of Minnesota.
Other impacts will include a deer takeover. Now, deer populations in the boundary waters are thin, about one animal per square mile, and many of those animals migrate to the warmer strip along Lake Superior in the winter. High deer populations will pose a threat to seedlings, Frelich said.
Warming also will bring a higher frequency of harsh storms such as the supercell storm system that produced huge downbursts on July 4, 1999, across the boundary waters, stripping 400,000 acres of trees.
“I would love to be completely wrong about this whole (global warming) thing,” he said, “but invasives are coming regardless of global warming.”
Alien species
Invasives have already transformed the forest floors over most of Minnesota, with inevitable changes to the canopy ahead.
And some of them are invasives most of us don’t know are aliens. Which aliens?
Earthworms and nightcrawlers.
Most Minnesota forest duff ecosystems have been or are being consumed by these two species of alien worms, which eat decaying leaves. That leaf litter is vital for germination for many species of trees and shrubs, and what has developed in many Minnesota forests is a relatively sterile understory of a species of grass.
While earthworms in farming and garden situations can help introduce nitrogen into those growing systems, in forests they rob nitrogen.
The Asian import emerald borer is only one of the other invasives on Frelich’s mind these days, as well. The borers have killed forests of several types of ash in other portions of this country, and Frelich pointed out that eradication efforts have proven useless.
Black ash, susceptible to the borer, makes up the majority of wetland hardwood forest in northeastern Minnesota, and Frelich fears the species may largely disappear, another drastic change to the forest in the area.
“The ecosystem does not care,” Frelich told the audience. “Whatever’s left will take over. It’s only people who care.”
What to do
Frelich indicated several options for responding to the coming crisis, though none appear able to stave off the approaching change.
He recommends managing the swelling deer herd, an expertise the DNR already has. He also suggested starting a seed bank so varieties that die out can be replanted if it becomes feasible, and that tree varieties resistant to disease and invasives be developed. He also suggested spirited defense of individual stands of trees.
And Frelich left the audience with a provocative question.
“When all that happens, will the BWCAW still meet the definition of wilderness?”
Contact Foss at (218) 365-3114 or ely@timberjay.com.
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