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Plagues
devastating forests across the U.S. West – ‘We’re talking
millions of trees killed, whole mountain sides dying’
22
September, 2016
By
Oliver Milman and Alan Yuhas
19
September 2016
(Guardian)
– JB Friday hacked at a rain-sodden tree with a small axe,
splitting open a part of the trunk. The wood was riven with dark
stripes, signs of a mysterious disease that has ravaged the US’s
only rainforests – and just one of the plagues that are devastating
American forests across the west.
Friday,
a forest ecologist at the University of Hawaii, started getting calls
from concerned landowners in Puna, which is on the eastern tip of
Hawaii’s big island, in 2010. Their seemingly ubiquitous ohi’a
trees were dying at an astonishing rate. The leaves would turn
yellow, then brown, over just a few weeks – a startling change for
an evergreen tree.
“It
was like popcorn – pop, pop, pop, pop, one tree after another,”
Friday said. “At first people were shocked, now they are resigned.
“It’s
heartbreaking. This is the biggest threat to our native forests that
any of us have seen. If this spreads across the whole island, it
could collapse the whole native ecosystem.”
Almost
six years later and nearly 50,000 acres of native forest on the big
island are infected with rapid ohi’a death disease. Rumors abound
as to its origin: did it emerge from Hawaii’s steaming volcanoes? A
strange new insect? Scientists still aren’t sure of where it came
from or how to treat it. […]
Forestry
officials and scientists are increasingly alarmed, and say the
essential role of trees – providing clean water, locking up carbon
and sheltering whole ecosystems – is being undermined on a grand
scale.
California
and mountain states have suffered particularly big die-offs in recent
years, with 66m trees killed in the Sierra Nevada alone since 2010,
according to the Forestry Service.
In
northern California, an invasive pathogen called Sudden Oak Death is
infecting hundreds of different plants, from redwoods and ferns to
backyard oaks and bay laurels. The disease is distantly related to
the cause of the 19th-century Irish potato famine, and appears to
have arrived with two “Typhoid Marys”, rhododendrons and bay
laurels, said Dr David Rizzo, of the University of California, Davis.
“We’re
talking millions of trees killed, whole mountain sides dying,”
Rizzo said. […]
Five
years of drought in the west have not only starved trees of water but
weakened their defenses and created conditions for “insect
eruptions” across the US, said Diana Six, an entomologist at the
University of Montana. Bark beetles and mountain pine beetles,
usually held in check by wet winters, now have more time to breed and
roam. The latter have already expanded their range from British
Columbia across the Rockies, to the Yukon border and eastward, into
jack pine forests that have never seen the bug.
The
outbreak is “something like 10 times bigger than normal, I would
argue a lot more than that,” Six said. “Basically a native insect
is acting outside of the norm, because of climate change, and become
an exotic in forests it’s never been before. We haven’t seen very
good outcomes of exotics moving into native forests.” [more]
Progressive
forest canopy water stress in California, 2011-2015. Graphic: Gregory
Asner / Carnegie Institute for Science
By
Robin Azer
17
September 2016
(Snow
Brains) – In the Sierra Nevada mountain region of California, the
customary green vista associated with a healthy forest has been
usurped by a deathly reddish-brown hue. According to the US Forest
Service a staggering 66 million trees have died since 2010, with more
than a third in the past year alone.
The death toll has risen sharply
due to years of drought and an ever-increasing population of bark
beetles. These pesky, hole-boring, eating machines have taken full
advantage of the trees’ vulnerability. The result is a huge swath
of land infested with an upsurge in bark beetles and millions of dead
trees.
“Nobody
imagined this would come on as fast as it has, or be as lethal,”
says Craig Thomas, conservation director for Sierra Forest Legacy, a
coalition focused on Sierra Nevada national forest issues. “And
nobody really knows what the hell to do.”
Historically,
the go-to strategy would be to fire up the chainsaws and remove all
the dead trees. In populated areas or those near power lines, it’s
still the industry standard. Top government officials including the
governor of California, Jerry Brown and Tom Vilsak, U.S. Agriculture
Secretary, side with the belief that logging will preempt the risk of
catastrophic wildfires. But when the area of destruction covers over
6 million acres, scientists are saying not so fast. After all, those
millions of felled trees need to be disposed of, creating a whole new
set of problems. Think greenhouse gases. Not to mention the risk to
the ecosystems of the remaining plant and wildlife. [more]
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