Lodgepole pine face
epidemic
Mountain pine
beetles sweep through SNRA
By GREG
STAHL
Express Staff Writer
A slowly
advancing wave of death is rolling across portions of the Sawtooth
National Recreation Area.
Mountain
pine beetles have decimated lodgepole pine forests in the Salmon River
Canyon and on several of the Sawtooth’s glacial moraines and hillsides.
Red-brown pine needles and dead trees are left in their wake.
"It
has really kind of exploded in the past few years," SNRA Forester Jim
Rineholt said. "Many people think it’s not a natural process, but
it’s really a natural process at work."
The dead
trees the beetles leave behind are excellent habitat for woodpeckers,
including several sensitive species that call the SNRA home, SNRA
Biologist Robin Garwood pointed out. Additionally, the beetles leave
behind fire-prone tree skeletons, which, when they burn, help renew the
life cycle for an entire lodgepole forest.
Rineholt
said the beetles usually attack 8- to 12-inch diameter trees that are 80
years or older.
"They
like to hit the larger, more mature trees because they have more food for
them," Rineholt said.
The beetles
have killed more than 4,000 trees in SNRA campgrounds, alone. Numbers of
dead trees on the SNRA as a whole are more appropriately measured in acres
rather than trees, because so many have fallen prey. On the SNRA, about
7,000 acres of lodgepole pine trees are or have been infested. That
translates to more than 26,000 trees, Rineholt said.
Mountain
pine beetles are the "most important native bark beetle pest of
mature pines in the Western United States," according to a Forest
Service information pamphlet. "Epidemics can build rapidly and kill
hundreds to millions of mature trees each year."
Mountain
pine beetles experience four life stages: egg, larva, pupa and adult. The
beetles have one generation per year and typically take one year to
complete a life cycle. Most spend winters as larvae, when they eat, and
kill, host trees. Adults emerge from host trees and infest others during
July and August.
The effects
of beetles’ feeding is not apparent until the summer following an
infestation.
Female
beetles initiate the attacks when they lay up to 48-inch-long
"galleries" of eggs beneath a tree’s bark.
The spring
after a tree has been successfully attacked, it begins to fade. Foliage
typically turns yellowish, then red-orange, and finally red-brown. After
two or three years, most needles fall from a dead host tree.
To avert
the beetles’ damage in campgrounds and highly visible areas, the Forest
Service is using an insecticide called Carbaryl, which can prevent a tree
from becoming infested.
The Forest
Service must adhere to strict guidelines when using the insecticide.
Because Carbaryl can be fatal to all insects, including those in rivers,
it cannot be sprayed within 50 feet of a stream or river, or during heavy
winds.
But many of
the SNRA’s forests will remain unprotected, while the natural process
continues.
"One
thing we know about the Sawtooth Valley is there’s no shortage of
mature, good-size lodgepole pine," SNRA Recreation Specialist Lisa
Stoeffler said.
"I
think they’re going to go pretty strong here for the next couple of
years," Rineholt added.