This article was sent to me by a friend. It is significant in that it is a larger indicator of what is happening on a smaller scale in our personal environments.
Contact: Richard Waring
541-737-6087
Oregon State University
Climate change causing massive movement of tree species across the West
CORVALLIS, Ore. – A huge "migration" of trees has begun across much of
the West due to global warming, insect attack, diseases and fire, and
many tree species are projected to decline or die out in regions where
they have been present for centuries, while others move in and replace
them.
In an enormous display of survival of the fittest, the forests of the
future are taking a new shape.
In a new report, scientists outline the impact that a changing climate
will have on which tree species can survive, and where. The study
suggests that many species that were once able to survive and thrive
are losing their competitive footholds, and opportunistic newcomers
will eventually push them out.
In some cases, once-common species such as lodgepole pine will be
replaced by other trees, perhaps a range expansion of ponderosa pine
or Douglas-fir. Other areas may shift completely out of forest into
grass savannah or sagebrush desert. In central California, researchers
concluded that more than half of the species now present would not be
expected to persist in the climate conditions of the future.
"Some of these changes are already happening, pretty fast and in some
huge areas," said Richard Waring, professor emeritus at Oregon State
University and lead author of the study. "In some cases the mechanism
of change is fire or insect attack, in others it's simply drought.
"We can't predict exactly which tree (species) will die or which one
will take its place, but we can see the long-term trends and
probabilities," Waring said. "The forests of our future are going to
look quite different."
Waring said tree species that are native to a local area or region are
there because they can most effectively compete with other species
given the specific conditions of temperature, precipitation, drought,
cold-tolerance and many other factors that favor one species over
another in that location.
As those climatic conditions change, species that have been
established for centuries or millennia will lose their competitive
edge, Waring said, and slowly but surely decline or disappear.
This survey, done with remote sensing of large areas over a four-year
period, compared 15 coniferous tree species that are found widely
across much of the West in Canada and the United States. The research
explored impacts on 34 different "eco-regions" ranging from the
Columbia Plateau to the Sierra Nevada, Snake River Plain and Yukon
Highlands.
It projected which tree species would be at highest risk of
disturbance in a future that's generally expected to be 5-9 degrees
Fahrenheit warmer by 2080, with perhaps somewhat more precipitation in
the winter and spring, and less during the summer.
Among the findings:
Some of the greatest shifts in tree species are expected to occur
in both the northern and southern extremes of this area, such as
British Columbia, Alberta, and California.
Large declines are expected in lodgepole pine and Engelmann
spruce, and more temperate species such as Douglas-fir and western
hemlock may expand their ranges.
Many wilderness areas are among those at risk of the greatest
changes, and will probably be the first to experience major shifts in
tree species.
Some of the mild, wetter areas of western Oregon and Washington
will face less overall species change than areas of the West with a
harsher climate.
More than half of the evergreen species are experiencing a
significant decrease in their competitiveness in six eco-regions.
Conditions have become more favorable for outbreaks of diseases and insects.
Warming will encourage growth at higher elevations and latitudes,
and increased drought at the other extremes. Fire frequency will
continue to increase across the West, and any tree species lacking
drought resistance will face special challenges.
"Ecosystems are always changing at the landscape level, but normally
the rate of change is too slow for humans to notice," said Steven
Running, the University of Montana Regents Professor and a co-author
of the study. "Now the rate of change is fast enough we can see it."
Even though the rate of change has increased, these processes will
take time, the scientists said. A greater stability of forest
composition will not be attained anytime soon, perhaps for centuries.
"There's not a lot we can do to really control these changes," Waring
said. "For instance, to keep old trees alive during drought or insect
attacks that they are no longer able to deal with, you might have to
thin the forest and remove up to half the trees. These are very
powerful forces at work."
One of the best approaches to plan for an uncertain future, the
researchers said, is to maintain "connective corridors" as much as
possible so that trees can naturally migrate to new areas in a
changing future and not be stopped by artificial boundaries.
###
Also collaborating on the research was Nicholas Coops at the
University of British Columbia. The work has been supported by NASA,
and the study is being published in two professional journals,
Ecological Modeling and Remote Sensing of Environment.
No comments:
Post a Comment