Update: Climate and Species Refugees

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Subject: Update: Climate and species refugees
From:    “Lance Olsen” <lance@wildrockies.org>
Date:    Sat, June 28, 2008 6:23 am
To:      “cmcr-outreach” <cmcr-outreach@vortex.wildrockies.org>
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Among other things, an article in this week’s
issue of Science underscores Rule #1 for anyone
who leads nature walks for public education
purposes: What you see is not what you’ll get —
especially, community composition/habitat types
cannot remain as we see them now, because these
eggs are already being scrambled.

Here’s how Scientific American reviewed the
Science article. (I have the article as pdf. Feel
free to ask.)
Lance
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“The researchers found that grasses, herbs and
other short-lived species that had been through
many generations shifted the most in search of
perfect temperatures, whereas long-lived trees
stayed largely in place. According to the
authors, this is changing the composition of the
forest-mixing formerly low-altitude grasses with
high-altitude trees-which could potentially
affect the entire ecosystem, particularly the
animals that rely on specific plants to survive.”

“Even if adult tree species suffer from hard
conditions, they are still present so you can’t
see any changes,” he says. “But seedlings perhaps
don’t appear in lower elevations that are too
warm.”
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Scientific American
June 26, 2008

Climbing Trees: Plants Move Uphill as World Warms
Surveys show French forests are changing in response to a warming climate
By David Biello

Global warming is leaving trees behind, according
to a new study in Science. An analysis of forest
species in six French mountain ranges (the
western Alps, northern Pyrenees, Massif Central,
western Jura, Vosges and the Corsican range)
shows that more than two thirds of them moved at
least 60 feet (18.5 meters) higher on the
mountainsides per decade during the 20th century.

“Among 171 species, most are shifting upwards to
recover temperature conditions that are optimum,”
says ecologist and lead study author Jonathan
Lenoir of AgroParisTech in Nancy, France.
“Climate change has already imposed a significant
effect in a wide range of plant species not
restricted to sensitive ecosystems.”

Previous research has shown that plants at the
highest elevations on mountains (and in the polar
regions) have been shifting to adjust to global
warming. But this is the first confirmation that
entire ecosystems in lower, more temperate
regions are moving as well.

“Species are not just moving at the extremes of
their ranges,” says ecologist and co-author Pablo
Marquet of the Pontificia Universidad Católica de
Chile in Santiago. “What we show is that they are
moving everywhere.”

In an effort to gauge the effect of climate
change on ordinary plant life, researchers
measured where the best growing conditions on the
mountains were for species of trees, grasses,
herbs, ferns and mosses. They discovered that
those for 118 of the studied species-from the
herblike three-horned bedstraw (Galium
rotundifolium) to whitebeam trees (Sorbus
aria)-migrated to higher elevations as
temperatures warmed.

The researchers found that grasses, herbs and
other short-lived species that had been through
many generations shifted the most in search of
perfect temperatures, whereas long-lived trees
stayed largely in place. According to the
authors, this is changing the composition of the
forest-mixing formerly low-altitude grasses with
high-altitude trees-which could potentially
affect the entire ecosystem, particularly the
animals that rely on specific plants to survive.

Plant ecologist Gian-Reto Walther of the
University of Bayreuth in Germany says it is
unclear what this finding bodes for the broader
ecosystem.

Lenoir notes, for instance, that even though tree
species did not show much sign of movement over
the past century, that climate change may affect
the next generation. “Even if adult tree species
suffer from hard conditions, they are still
present so you can’t see any changes,” he says.
“But seedlings perhaps don’t appear in lower
elevations that are too warm.”

But long-lived and slow-moving trees may
ultimately be able to catch up with their
smaller, faster counterparts. “As long as the
older trees are not so stressed that they do not
produce many viable seeds, [and] the dispersal
mechanism-for example, wind, birds, mammals-is
present, and the habitat where the seed lands has
the appropriate soil, nutrients and temperature,”
says biologist Terry Root of Stanford University,
who was not involved in the study, “then the
trees will be able to shift.”

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