[Marxism] Sequoias are threatened by climate change
lnp3 at panix.com
Tue Aug 12 10:11:14 MDT 2014
NY Times, August 12 2014
Tall, Ancient and Under Pressure
By JIM ROBBINS
SEQUOIA NATIONAL PARK, Calif. — High in the Sierras, biologists are
struggling to find ways to protect some of the world’s oldest and most
storied trees from drought, forest fires and climate change.
The trees are the giant sequoias, some of them 2,000 to 3,000 years old,
and they are just one of several ancient Western species, including
redwoods and bristlecone pines, that face a daunting future.
Although the sequoias are not at immediate risk, even from California’s
current drought, scientists say they were not built to withstand decades
of dry and warming weather. Their seedlings and saplings are susceptible
to fires, which are likely to increase, especially at higher elevations.
And if the drought persists, the lack of melting snow may keep the
seedlings from developing a robust root system.
“If there’s long-term drought, within 25 years, we could see seedlings
in trouble,” said Nathan Stephenson, an ecologist with the United States
Geological Survey. “In 50 years, the whole population could be in
trouble,” he went on, and within a century “most of the big trees could
Sequoias are found in only one place on earth: the Sierra Nevada
Mountains in California. There are 65 to 70 groves, most in a narrow
70-mile band on the west side of the range at 5,000 to 8,000 feet. They
include one tree here called the General Sherman, the world’s largest by
volume. Preservation efforts are hampered by the fact that so little is
known about big trees, from their root systems to how they die.
As the climate changes, so do conditions in which sequoias and other big
trees grow. The coastal redwoods of California, for example, are fog
drinkers, taking as much as 40 percent of their water in through their
needles. In the past half-century, the number of days in which the trees
are shrouded by fog has declined by 30 percent.
In some places, that appears, paradoxically, to be contributing to
increased growth: With less fog cover there is more light, said Todd E.
Dawson, a biologist at the University of California, Berkeley. But on
the redwood range’s southern and eastern edges, which are warmer and
drier, scientists are documenting changes in the big trees.
“They are self-pruning,” Dr. Dawson said. “The crowns are beginning to
thin out, and they are dropping needles.”
Climate change is one of a host of complex factors in the health of big
trees. Many forests have been weakened from previous stresses, including
habitat fragmentation, air pollution and selective breeding for timber.
Warmer temperatures can also usher in disease and insects, along with fire.
Bristlecone pines — at 4,000 years or more the oldest trees in the world
— have adapted to some of the harshest conditions on the continent. But
rapid warming atop mountain ranges in Colorado, New Mexico and elsewhere
has allowed bark beetles to gain a foothold. Once the bristlecones are
infected, nothing can be done to save them. And although the beetle
threat has waned of late, the pines have also been hit by blister rust,
an invasive fungus from Asia.
Protecting such venerable trees is a challenge.
“We might start irrigating the sequoias,” Dr. Stephenson said, “or we
might build a giant fuel break around the giant sequoias, so if a fire
came toward the grove, we could defend it. These things are getting hard
Sequoias are resilient. They have no disease or serious insect enemies,
and their spongy bark, eight inches thick, is highly resistant to fires.
One can lose 95 percent of its crown in a fire and recover. Still, no
one knows what the climate future holds.
A novel program by Sierra Pacific Industries, a lumber producer and the
largest landowner in California, has gathered cones from old-growth
sequoia groves. In 2012, foresters started to plant seeds in 16
locations with different soil types, elevations and precipitation
levels. Some 130,000 seedlings, the tallest three to four feet, are now
growing from the ancient seeds. The company program is aiming to grow
1.4 million, even though sequoias have little timber value.
“The goal is to conserve the genetic diversity of the native groves”
should the old trees die, the program’s coordinator, Glenn Lunak, said.
For bristlecone pines, biologists are collecting seeds from trees that
appear resistant to blister rust, growing them in a test lab in Oregon
and inoculating them with the fungal disease to gauge their resistance.
If they contract the disease and survive, they will be planted as part
of a new bristlecone forest among the old trees.
“We’re trying to stay ahead of the rust and manage for resilience,
rather than getting behind the curve and having to rebuild ecosystems
impacted by high mortality,” said Anna W. Schoettle, an ecologist with
the United States Forest Service in Fort Collins, Colo.
Big trees are on the front lines of climate change. A 2012 study in the
journal Science found that 100- to 300-year-old trees were dying at high
rates around the world, in part because of hotter and drier weather.
“It’s a very, very disturbing trend,” said an author of the paper, Bill
Laurance, an environmental scientist at James Cook University in
Australia. “We are talking about the loss of the biggest living
organisms on the planet, of organisms that play a key role in regulating
and enriching our world.
“A world where a child can’t stare up in wonder at a giant
cathedral-like crown is a very real possibility.”
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