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Minnesota has an immigration problem: Bugs, birds, critters and plants are overtaking the landscape

By Ron Way | Friday, March 14, 2008
The Mountain Pine Beetle and the emerald ash borer are moving to the state. Wild turkeys, opossums and raccoons are heading to northern Minnesota. White tail deer have taken over everywhere.

The Mountain Pine Beetle and the emerald ash borer are moving to the state. Wild turkeys, opossums and raccoons are heading to northern Minnesota. White tail deer have taken over everywhere. And Duluth is getting an influx of new residents — cardinals.

Climate change is the reason Minnesota’s insect, animal and bird populations are changing, but according to several new reports and studies, the effects on the state in the coming years will be even more profound and widespread.

By the time today’s high school students retire, for example, boreal forests that help define Minnesota’s outdoor character may be largely gone, according to Nancy Lange, clean air advocate for the Midwest office of the Izaak Walton League (IWL) and author of a national report on how outdoor recreation will be affected as the climate moderates.

And by the time those students reach middle age, North Shore streams may be devoid of their prized brook trout, says Lange, who points out that  warming is certain to be more pronounced in Minnesota than any other flatland region in the country.    

Lange’s report is the latest caution by experts about the accelerated pace of climate change. At a recent seminar, University of Minnesota environmental chemist Deborah Swackhamer projected that by the end of the century Minnesota’s climate will be similar to what is today experienced in Kansas. 

Key lakes monitored
While the Legislature and Gov. Tim Pawlenty have responded with initiatives to reduce carbon emissions linked to global warming and to further develop “clean fuels” like solar, wind and cellulosic ethanol, two state agencies have begun an intensive effort to devise ways to protect the heartbeat of Minnesota’s outdoor-recreation economy, its lakes. 

The Department of Natural Resources (DNR) and Pollution Control Agency have embarked on a four-year program called SLICE (for Sustaining Lakes In a Changing Environment) to closely monitor how and why 24 representative lakes across the state are changing and to come up with steps to mitigate harmful effects.

The task won’t be easy, warns DNR fisheries researcher Don Pereira. He said that extensive lakeshore development has resulted in the removal of shoreland vegetation and bulrushes in near-shore zones, septic systems that often don’t work and fertilized lawns to the edges of lakes.  Together, the physical changes have produced nutrient overload that depletes lakes of life-sustaining oxygen and makes them more vulnerable to the added stress of climate warming.

What is certain, said aquatic biologist Dann Siems of Bemidji, is that many lakes — some of the state’s most popular among them — will undergo radical, unwanted change like turning pea green in late summer as blue-green algae take over and, even, experiencing the disappearance of desired game fish. 

Subtle change is already occurring.  

Herds of the adaptable white tail deer have exploded while the heat-intolerant moose have declined sharply and could disappear from the state. The once-rare wild turkey and opossum now range over much of Minnesota and raccoons are seen much farther north.  Cardinals, once absent in Duluth, are now regular visitors to feeders there. 

Duluth has also seen another change, says Mark Martell of the Audubon Society:  some pelagic gulls that historically migrated along the Pacific Coast now follow inland routes and are showing up in the Great Lakes region.   

Last fall, gardeners noticed that tomatoes, beans, egg plant, basil and pepper were still productive into October, which is noticeably later than normal.  Impatiens, usually among the first to die off in early fall, were still in blossom around Halloween. 

“If you have your eyes and ears open, nature is speaking to us,” said Don Arnosti, forestry director for the Minneapolis-based Institute for Agriculture and Trade Policy.  He said he’s noticed numerous shrub oak on a recent trek into the Boundary Waters Canoe Area, unusual in that part of the state.

Entomologists David Andow of the University of Minnesota and Rob Venette with the U.S. Forest Service worry that trees could soon be invaded by destructive insects that previously could not survive winters here. That would turn the woodland into tinderboxes of dead and dying wood that would bring economic stress and increased forest fires like last spring’s Ham Lake blaze along the Arrowhead’s Gun Flint Trail.    

Venette said it’s only a matter of time before the Mountain Pine Beetle shows up here and attacks trees as it does in Western forests.  A more imminent threat is posed to ash trees by the emerald ash borer that’s already wiped out the popular shade tree in Michigan, Chicago and parts of Wisconsin in an inexorable expansion into Minnesota as warming winters cease to provide an effective natural buffer.   

“Forests and the animals that live in them have evolved together,” Lange wrote in her report. “As the forest changes, wildlife living within the forest must also adapt, migrate or die off.  Most tree species, however, will not be able to migrate fast enough.”

Minnesota in the crosshairs of change
But what is it about the state that Lange says makes the region more susceptible to the effects of climate change?

Minnesota is situated on the edge of three important biomes where change is first felt. 

Minnesota’s geographical center-point in North America puts it at a climactic crossroads where eons of converging weather patterns have shaped the western prairie (influenced by Pacific air whose moisture is sapped by mountains) and the northeast’s forest (influenced by cold Polar air) separated by a transitional deciduous hardwoods zone (influenced by humid Gulf Coast air). 

That puts Minnesota is in the crosshairs of climate change, and while change has always occurred over time it’s the pace of the present change that is worrisome. Plant and animals can adapt, Lange says, but many species can be wiped out when change occurs as quickly as climate models suggest that it will. 

According to Lange’s report, here are changes that have occurred in Minnesota and others that are likely: 

• Brook trout populations will likely decline. Brook trout prefer cold water. But the source of most North Shore streams is surface lakes that will gain temperature with climate change. As a result, the streams themselves will be warmed to levels intolerable to trout. 

• Moose populations have declined from 4,000 20 years ago to about 250 today. One theory for the decline is that warming temperatures have caused cold-loving moose to expend too much energy to keep cool, making the stressed animals vulnerable to tick-borne disease. 

• Warmer surges of Pacific and Gulf Coast air are acting to push back against Polar air masses that have maintained the conifer woodlands of northeastern Minnesota. The result is that the southern edge of boreal forests that define the Arrowhead region are giving way to maples, oak, and other hardwoods now common along a diagonal southwest-northwest band through the state.   The boreal will eventually recede into Canada, and even the succession hardwoods will be vulnerable to overgrazing by burgeoning deer populations.     

• Wetlands of eastern North Dakota and South Dakota provide prime breeding habitat for waterfowl that migrate along the Mississippi Flyway, and as climate warming dries remaining potholes in the Dakotas the ducks and geese will naturally move east to seek nesting habitat.  But 90 percent of Minnesota’s wetlands have been drained for farmland and urban development, and so it’s expected that waterfowl populations will suffer dramatic decline. 

• Minnesota’s 12,000 lakes and 93,000 miles of streams and rivers are likely to suffer. Warming surface waters in lakes will mean streams those lakes feed will be warmer and the fish species in those lakes and streams will change. Lakes are most vulnerable because a warming climate means warmer water that produce algal invasions that discolor lakes and kill fish. Lakes already stressed by unchecked lakeshore development are likely to suffer most.

Ron Way, a former reporter for several Midwest newspapers, covers the environment and energy issues. He can be reached at rway [at] minnpost [dot] com.