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“Eighty years from now warming temperatures will shift climatic
conditions up to seven degrees in latitude, Aitken says. So trees in
Prince George, B.C., for example, will weather summers and winters
indigenous to places like Idaho with potentially harmful effects.”
“We want to plant trees that will be healthy and grow well, but
conditions are going to change throughout their lifetime,” Aitken
says. “If you move trees north early on, the seedlings will die from
cold-related injury. But if you plant them where they’re well adapted
as seedlings now, in 60 years where it’s four degrees warmer, mature
trees may not be well-adapted. We don’t know how to target that yet.”
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The London Free Press (Canada)
October 28, 2007
Moving targets a challenge
By VIVIAN SONG, NATIONAL BUREAU
YELLOWKNIFE — When Kevin Kennedy saw the unfamiliar four-legged
animal saunter past his living room window, he went through a mental
checklist of what it could have been.
“My mind went through all the possibilities,” said the seven-year
Yellowknife resident and city councillor.
The animal was a coyote, a normally south-dwelling animal that, up to
a few years ago, was a stranger to these parts. But sightings of
animals never seen in Yellowknife before have been on the rise, like
white-tailed deer, cougars and magpies which are migrating further
from their traditional habitats.
Experts warn that climate change could push Canada’s tree line north
by as much as 750 km in some areas, and bring with it new species
while pushing old ones out.
“That will reduce the space for tundra and the wildlife it supports,”
points out Stewart Cohen, a senior researcher at Environment Canada.
“Alpine trees may also be squeezed out if trees move to higher and
higher elevations.”
An increasing frequency of fires is expected to cut swaths through
the fir, jack pine, and black and white spruce trees which dominate
the boreal forest. Meanwhile, deciduous species like the leafy aspen,
birch and poplar are projected to succeed their needly predecessors
and change the face of the largely coniferous boreal forest in the
next 50 years.
“As trees become more dense because a warmer climate allows them to
grow taller, it will shift the ecosystem and plant species,” explains
Tom Lakusta, forest manager with the government of the Northwest
Territories.
Subspecies of the black and white spruce, which grow in northern
Alberta and Ontario, may also become better suited to the soils of
their northern cousins, Lakusta says, and creep farther north.
According to Environment Canada, warmer temperatures will force sugar
maple production in Quebec to shift northwards by two degrees of
latitude over the next century. Already, sap flow has started up to
one month earlier over the last decade and production seasons are
shorter.
“One of the big challenges is we’re trying to hit a moving target,”
says Sally Aitken, director of the Centre for Forest Gene
Conservation at the University of British Columbia.
Eighty years from now warming temperatures will shift climatic
conditions up to seven degrees in latitude, Aitken says. So trees in
Prince George, B.C., for example, will weather summers and winters
indigenous to places like Idaho with potentially harmful effects.
“The problem with climate change is that tree species are going to be
in the wrong places … there’s going to be a big mismatch between
the trees and their local environment,” Aitken says.
That presents a conundrum for forest conservationists.
“We want to plant trees that will be healthy and grow well, but
conditions are going to change throughout their lifetime,” Aitken
says. “If you move trees north early on, the seedlings will die from
cold-related injury. But if you plant them where they’re well adapted
as seedlings now, in 60 years where it’s four degrees warmer, mature
trees may not be well-adapted. We don’t know how to target that yet.”
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