[Marxism] How global warming is changing Minnesota: Prairies are replacing forests
binesi at gvtel.com
Thu Aug 12 11:44:39 MDT 2010
BWCA blowdown and aftermath show how global warming is changing
Minnesota: Prairies are replacing forests
By Steve Berg | Thursday, Aug. 12, 2010
Last Saturday was too hot and muggy for a 30-mile bike ride. But since I
was never the smartest kid in class, there I sat, dismounted, panting
and sweating on a bench in Mears Park, thankful for a cold soda from the
drink cart and all those tall, shady trees.
This is my favorite urban park in the Twin Cities, an island of green
loveliness surrounded by some of St. Paul's most beautiful historic
buildings. Yet on a day so sweltering, not even this spot could keep my
mind from drifting toward cooler climes. I imagined the piney shores of
Lake Superior and the sparkling lakes of the Boundary Waters before
recalling Lee Frelich and his disturbing discovery about what's
happening to Minnesota's north woods. It kind of took the edge off my
Remember the big blowdown of 1999? Starting on the afternoon of July 4,
a massive derecho packing violent winds of more than 90 mph swept along
the U.S.-Canada border for 1,300 miles. In all, the storm lasted 22
hours. It blew down nearly a half million acres of trees in the Superior
National Forest, including about 40 percent of the trees in the Boundary
Waters Canoe Area Wilderness.
For Frelich, director of the University of Minnesota's Center for
Hardwood Ecology, the blowdown and its aftermath of fires and forest
regeneration confirmed on a massive scale what he had long suspected:
The new north woods growing up to replace the millions of blown down
trees isn't really a north woods at all but something more akin to the
grassland savannahs farther south. Indeed, over the last decade or so,
the blowdown has become a giant laboratory for measuring the ecological
effects of a warming climate and the role humans are playing in
accelerating the change.
*Prairie replaces forest*
Most of the trees lost in the storm were pines and aspens, Frelich told
me this week. By normal succession, they would be replaced initially by
varieties of spruce, fir and cedar. But instead red maple, basswood and
other species normally found farther south are sprouting on the forest
floor. "Recently I was at Snowbank Lake near Ely and I was just amazed
to see all the red maple coming up," he recounted.
Frelich admits that until the last few years his observations greatly
depressed him. He loves the woods, after all. He grew up in the grip of
Sigurd Olson's lyrical writings about the magic of the northern
wilderness. To realize that Minnesota's thick, dark canopy of conifers
would be replaced by, in Frelich's words, "a scrubby, species-poor
landscape" was not a pleasant prospect. But he's no longer angry. He
tries to see the blowdown in a broader perspective ? as part of the
paleo-ecological record and as an opportunity to gather more data to
chronicle the changes ahead. He holds out little hope than humans will
alter their carbon habits enough to prevent the intrusion of prairie
into the forest.
A journal article to be published next month in Frontiers of Ecology and
Environment <http://www.frontiersinecology.org/> further documents
Frelich's findings. He and his U colleague Peter B. Reich, professor of
forest ecology and tree physiology, explore likely changes over the next
50-100 years in the composition of northern forests due to global warming.
"Under a scenario of human-induced global warming, the prairie biome
will shift to the northeast and displace existing forests," the paper
declares. Here's a summary of its observations:
Think of Minnesota as having an ecological border running across it
diagonally, northwest to southeast. To the northeast, boreal forests
dominate the landscape. To the southwest, savannahs ? prairies with
small trees that do not close to form a canopy ? prevail. Over the last
million years, the border has shifted eight times, but this time is
different; the conifer forests are retreating to northeast farther and
faster than before because there are higher levels of carbon in the
atmosphere (twice the pre-industrial concentration).
*A perfect storm of events*
Likely accompaniments to this ecological trend? A warmer, drier climate
that outstrips the ability of tree normal species to keep pace with the
change; a greater rate of evaporation; more severe wind storms; a
greater number of severe fires that give warmer-climate plants a better
opportunity to invade; more exotic insects and diseases affecting trees;
an overabundance of deer that browse woody plants that would otherwise
grow into trees; and the further invasion of earthworms that disturb the
forest floor's ability to hold moisture. (As it turns out, nightcrawlers
and angleworms, imported to use as fishing bait, are not native to
"All of those factors are pushing the forest in the same [northeast]
direction," Frelich told me. "My best guess is that the BWCA Wilderness
will look more like a savannah than a boreal forest within five to 10
Altogether, he and Reich report in their writings an expectation that
the lost of forest along the prairie-forest border of central North
America could equal an area twice the size of California.
"There's no doubt that human activity has made this a unique,
super-charged event," Frelich said.
*Inpact on the urban landscape*
Frelich describes what might be called an ecological reset. Higher
levels of CO2 in the atmosphere have set off a chain of events. Plant
life adjusts to changing conditions. Forest becomes prairie. Habitats
change. Animals adjust.
Maybe it runs parallel to the reset taking place in the world of human
settlement. Jim Erkel, land use and transportation director for the
Minnesota Center for Environmental Advocacy <http://www.mncenter.org/>,
offers the analogy. Conditions for humans are changing. Not only do we
have a warming climate and an unstable energy supply, we have a
faltering economy and significant demographic shifts toward smaller
What's required is a reset, Erkel suggests, citing the Austrian
economist Joseph Schumpeter's theory of "creative destruction."
Economic crises sweep away outmoded companies, practices and systems,
clearing the way for entrepreneurs to introduce new technologies and new
ways of doing things that reignite growth.
In that context, we can't build cities the same old way, Erkel said.
Conditions require a spatial fix, a new development pattern that's more
that's more compact and energy efficient. Some people will resist these
changes, complaining about loss of basic freedoms, the rising price of
gasoline or the falling values of large suburban homes, for example. But
maybe, said Erkel, moral values aren't really involved. Maybe changes in
the urban form should be viewed as similar to the ecological adjustments
being made in Minnesota's northern forests.
"There is no right or wrong in the way nature resets itself to changing
conditions," he said. "It's just the way it happens."
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