Ferocious Bark beetles ravaging western CANADA/ US forests
Pastor Dale Morgan
Ferocious Bark beetles ravaging western CANADA/ US forests*
MISSOULA, Montana, Dec 8 (AFP) Dec 08, 2006
The forests of the American and Canadian West are under siege from bark
beetles, miniscule but mighty foes that are ravaging the region's
leading trees in record numbers.
Scientists say a warming climate is behind the beetle epidemic which has
killed vast swaths of spruces, pines and firs in some of the most
picturesque regions of the Rocky Mountains.
Experts say the region has failed in recent years to register the
sustained periods of sub-zero temperatures that once dealt a fatal blow
to beetle populations.
Although the insects have periodically attacked Western forests, an
outbreak affecting multiple tree species simultaneously in a string of
states - including Colorado, Idaho, Montana, Utah and Wyoming - has no
parallel.
"The main species that make up our forests are all under attack," said
Barbara Bentz, entomologist with the US Forest Service's Rocky Mountain
Research Station in Utah.
Studies show bark beetles are expanding their range into higher
elevations, where arctic conditions once froze them out, even as a
stepped-up reproductive cycle has sent their populations soaring.
"We're seeing beetles making inroads they've never made before," said
Jim Rineholt, forester with the federal Forest Service.
In addition to the absence of a killing cold, the beetles have benefited
from a long-standing drought that has weakened trees' defenses, and from
a decades-old strategy of suppressing the wildfires that historically
created a mosaic of tree types of different ages.
Officials took notice of the beetle outbreak in 2000, when the bugs
destroyed a higher-than-average number of conifers.
While the beetles are smaller than the tip of a pen, they have since
over-run mountain ranges, killing millions of their prime target -
towering, old-growth trees.
Utah is experiencing the largest spruce beetle infestation in the lower
48 states, with the insect already gnawing through close to half its
Engelmann spruce.
In Colorado, the number of lodgepole pines attacked by mountain pine
beetles increased almost fivefold in 2006, rising to 4.8 million from
1.1 million in 2005. The number far exceeds the trees destroyed by
wildfires or harvested by commercial loggers.
In central Idaho, bark beetles last year ate their way through 4.6
million lodgepoles and Douglas firs.
Scenic mountain views once carpeted with green now feature acres of red
and dead trees that offer little benefit to wildlife and even less to
the observer. From the exclusive ski resort of Vail, Colorado, to
Yellowstone National Park, some of the most prized western US recreation
areas are defaced with skeletal trees whose needles have browned with death.
"In some areas, we're seeing more black and brown than green," said
Scott Hicswa, a private forestry consultant in Montana.
Foresters have few weapons to combat large-scale beetle infestations.
They can can use chemicals to try to protect individual, high-value
trees, but once a tree is under attack the battle is over.
The female beetle starts the assault. Once a suitable tree is
identified, the female emits a chemical that attracts males and females,
setting off a mating frenzy. The female then bores beneath the tree's
bark and lays eggs as it ascends.
Hicswa says the West is facing landscape-level problems while lacking
landscape-level solutions.
"We do have the tools to address the problems at an area level but we
can't work as quickly as Mother Nature or at the scale," he said.
Experts can't agree how to interpret the long-term effects of the
epidemic even as they concede the short-term impact is devastating.
Some researchers predict a warming West will cause infestations to
worsen, turning forested peaks into barren vistas and leaving more
beetle-killed trees to fuel wildfires.
Others disagree, arguing the epidemic will come to a halt when
old-growth trees - which populate whole forests - have succumbed. And a
recent study by university researchers in Colorado and Idaho suggests
infested forests may have fewer fires because they will have less fuel
to feed the flames.
US Forest Service entomologists Dayle Bennett, Steve Munson and Ken
Gibson are among those who reject the "doom and gloom" scenario.
They argue that thinning of large, older trees makes way for younger,
more vigorous and less disease-prone trees.
In British Columbia, Canada, beetles have laid waste to 21.5 million
acres of forest and have marched eastward across the Rockies into
Alberta. But findings in Canada suggest beetles have changed their
habits in the absence of their preferred hosts, with some attacking
smaller and younger conifers.
"The epidemic is far greater than anything we've ever seen before," said
Ray Schultz, assistant deputy minister with British Columbia's Ministry
of Forests and Range.