Climate Change is Killing Hundreds of Thousands of Trees

Aspen Colorado may have to be renamed Deadwood, like the city in South Dakota.

Golden Aspens in Raggeds Wilderness Area, Rocky Mountains, Colorado, photo taken October, 2004. Corbis.

The Aspen trees which gave the city its name, which were already under stress from lack of water, are now being killed by insects.  Scientists call it Sudden Aspen Decline.  SAD.

Except that it’s not just happening to aspens, and it’s happening all over the world.  It’s happening in Central America to pine trees, it’s happening in the Midwest to elm and ash trees, it’s happening in the Southwest, it’s happening in Europe. Trees are dying.   Supposedly, no one can figure out why they’re dying, (according to the WSJ), yet everyone knows what’s causing it:  climate change.

Aspen trees are unique. They don’t grow from seeds, they grow like strawberries — with new shoots going out to form new plants. For several years, the shoot networks have been dying. The early theories about cause centered on  drought, but the drought has not gone away, and the trees are severely weakened.  The large picture points to climate change-caused droughts, which last a long time and in some cases appear to be permanent. As a result, Aspens may go extinct.  Many living things, like some trees, cannot survive climate change.

The worst part of so many trees dying is of course that when they die, the carbon sink they were also dies. We do know one thing: Global warming is not “good for plants”.   It’s terrible for plants.  The story of these trees dying off became part of the mainstream media a week ago when it was included in the NBC Nightly news.  In a few years, they may all be gone.

Global warming is blamed for aspen die-off across the West

Paonia, Colorado — From the hillsides of extinct volcanoes in Arizona to the jagged peaks of Idaho, aspen trees are falling by the tens of thousands, the latest example of how climate change is dramatically altering the American West.

Starting seven years ago, foresters noticed massive aspen die-offs caused by parasitical insects, one of them so rare it is hardly even written about in scientific literature. But with warming temperatures and the effects of a brutal drought still lingering, the parasites are flourishing at the expense of the tree, beloved for its slender branches and heart-shaped leaves that turn a brilliant yellow in autumn.

What foresters have termed Sudden Aspen Decline affects more than just aesthetics. Aspen trees provide a rich habitat for birds, elk, deer and other animals. The grasses that sprout under them — up to 2,000 pounds per acre — hold water that is needed by metropolitan areas. The trees do not burn easily and create natural firebreaks in forests already ravaged by the pine bark beetle — another parasite that is thriving because of global warming.

“It’s just rolling through the forests,” Wayne Shepperd, an aspen specialist at Colorado State University, said of SAD.

Noting the number of other changes to Western vegetation due to warmer, drier temperatures, he added: “Everything’s happening all at once. We’re living in interesting times here.”

The decline of the tree is most visible in Colorado, which has seen nearly 500,000 acres afflicted by SAD — nearly a fifth of its aspen groves.

Hillsides that used to draw tourists in the fall to gaze at the flickering aspen leaves are now populated only by the trees’ pale skeletons.

. . . .

Even before aspen trees began their abrupt die-off, the tree was under duress in the West.

Scientists estimate that the trees covered 10 million acres in the 19th century; now the number is 4 million.

. . . .

Dale Bartos, a Utah-based scientist with the federal Rocky Mountain Research Station, described the one stand in Lassen National Forest in Northern California, where fencing protects nine tiny aspen bulbs from foraging animals.

“We’re seeing these really extreme situations, where that’s all that’s left,” he said.

Now SAD [Sudden Aspen Decline] is accelerating that loss.

The syndrome was discovered in Colorado when rangers in two national forests in the southwestern corner of the state noticed disturbing die-offs in formerly lush stands.

Researchers concluded that warmer temperatures stressed trees, especially older ones that hadn’t been swept away by fire. They identified four parasites and one wasting disease that are now flourishing in the stands.

One of the parasites, the aspen bark beetle, is so rare that it had only been mentioned once before in an academic paper, scientists say.

“If the aspen were vigorous, these things would just be taking a minor role,” said Jim Worrall, a plant pathologist for the U.S. Forest Service.

The Terror Creek drainage west of Paonia, one area where SAD was first identified, remains the focus of an intensive research project on whether the syndrome can be halted. Researchers are testing whether cutting down older aspen trees in affected areas can combat the syndrome.

The remaining, younger shoots are less susceptible to SAD.

Shepperd has worked on the project and has been discouraged by the results so far. In stands with little SAD, the cutting approach — which he likens to amputation — has shown some success. But the syndrome and its accompanying parasites and disease have moved so fast that stands that once had low levels of exposure are now almost entirely affected.

“We looked at the data and said, ‘Oh my God,’ ” Shepperd said.

On a recent autumn afternoon, Levi Broyles, the forest ranger who oversees the Terror Creek area, drove up a rutted dirt road through the drainage, revealing stunning views of the western slope of the Rocky Mountains.

In the foreground, however, were acres of denuded aspens. Broyles, a laconic native Westerner, gestured at the dead forest. “Because of all the development down in the valley, this is the winter range” for elk and deer, he said.

Left unsaid: The once-shady ground under the dead and dying aspen would dry out in the sun, and the vegetation that would replace the lush grasses could be inedible to some animals.

They would have to look for their sustenance elsewhere, or starve.

He stopped at one stand of trees hit moderately by SAD — 20% to 60% of the aspens were infected.

He pointed to a saplike substance oozing from the bark of one tree, a sign of a borer eating away at it from inside.

Another tree’s bark was peeling, a sign of the disease Ceratocystis canker.

Broyles spoke matter-of-factly about the die-off but allowed that it had affected him.

“Forty percent of my half-million acres is aspen habitat,” he said.

“It’s definitely near and dear to my heart.”

He drove back down to Paonia. At the Forest Service station, receptionist Anne Williams asked where he had been. When Broyles replied that he’d been up at Terror Creek, she said people had been calling asking where they could see fall color. Was there any color at Terror Creek?

“No,” Broyles said tersely. “Terror Creek is gone.”

Source:  LATimes By Nicholas Riccardi,  October 18, 2009