Colorado - Bug thrive, transform state forests

Donald L Ferrt wolfbat359 at mindspring.com
Sun Feb 1 20:52:55 EST 2004


http://www.denverpost.com/Stories/0,1413,36~53~1921240,00.html

Article Published: Thursday, January 29, 2004  
Bug thrive, transform state forests
By Theo Stein
Denver Post Environment Writer

Drought and aging forests have combined to create an unprecedented
series of insect outbreaks that will change the look of some Colorado
landscapes for generations.

A dozen species of native beetle pests are attacking virtually every
coniferous-forest type in the state, from the piñon-juniper woodlands
of southern Colorado to the high-elevation spruce and fir forests of
the northern ranges, according to a new state report.

"I don't think we've seen insect activity in our forests on this scale
since the settlement period," said Tom Eager, an entomologist with the
U.S. Forest Service in Montrose. "In some areas, it's a jaw-dropper."

Scientists say beetles are the natural change agent for Western
forests. Over the long term, beetles help rejuvenate forest stands and
break up large blocks of old timber to the benefit of wildlife and
other vegetation.


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In some places, the beetles will leave hundreds or thousands of acres
of dead standing trees. In others, vulnerable trees will die, leaving
others to grow more vigorously in the newly created space.

In southwest Colorado, beetles are devastating a regional symbol.

"The piñon pine infestation is the worst we've ever seen," state
forester Jim Hubbard told Colorado lawmakers Wednesday. The outbreak
of ips beetles could kill 80 percent of the southwestern piñons before
it peters out. Piñon nuts are an important wildlife food that many
people harvest.

"We will lose most of our piñons due to this infestation and will have
to start over," Hubbard said.

The state's annual report on forest health, based on conditions last
year, paints an unsettling picture.

North of Steamboat Springs, dead spruce left by a raging spruce beetle
outbreak may still be visible 50 years from now.

An infestation of mountain pine beetle, which attacks ponderosa and
lodgepole pine, moderated last year for the first time since it began
in the mid-1990s. Hubbard said the beetles continue to inflict heavy
losses in Grand, Jackson and Eagle counties, and along the Front
Range.

"But we had 10 times too many trees to start with," said University of
Northern Arizona researcher Tom DeGomez. "So maybe this will be an
ecologically beneficial change."

Some tree and wildlife species may lose out; others will prosper.

Dormant aspen clones may burst back to life if beetles kill pines that
have shaded them out. Stands of dead trees will no longer draw water
during the growing season, potentially boosting groundwater and stream
flows.

Woodpeckers and birds that nest in tree cavities will likely flourish
in beetle-kill areas. Grasses, herbs and shrubs that root in dead
stands may attract deer and elk, or lynx and snowshoe hare.

But try telling that to a homeowner surrounded by dying pines,
suggests Eager. "It depends on what goggles you're wearing," he said.

Some foresters worry that dead trees will fuel wildfires, but others
note the biggest blazes are fanned by high winds that push flame
through canopies of live needles.

Virtually no part of the West has been spared. Mountain pine beetles
have hammered ponderosa pine in Arizona, DeGomez said. And the
relentless advance of blister rust through whitebark pine threatens to
wipe out a critical food source for grizzly bears.

But forest health experts say that infestations in high-elevation
forests, such as those north of Steamboat Springs, may be within the
range of natural variability.

The catastrophe afflicting piñon pine in the southwest is different.

The drought is the immediate culprit. The stage was set from 1975 to
1995, one of the wettest periods in a thousand years, said Colorado
State University professor Bill Romme.

"Trees grew and put on more biomass than could be supported in normal
conditions," he said. This drought, he noted, is not appreciably worse
than the 1950s dry spell.

What has changed are "unusually high" temperatures that Romme fears
may be linked to climate change. That has increased stress on trees
and allowed more beetles to breed each year.

Piñon stands may not recover for a century, said Romme, but he argued
against a massive clean up of dead pinons to reduce fire risk.

Studies show that after a year, dead trees are less flammable than
drought-stressed live trees. The fallen wood shades and shelters piñon
seedlings and provides perches for piñon jays that bury seeds and
plant new forests.

Denver Post staff writer Julia C. Martinez contributed to this report.



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