Researchers work to save whitebark pine

Researchers work to save whitebark pine

Posted 26 July 2011, by Craig Welch (Seattle Times), Miami Herald (McClatchey Company),

SEATTLE — The peculiar conifers with the massive fatty seeds and silvery trunks sprout way up on wind-swept slopes, where they’re central to high mountain ecology.

Whitebark pine trees provide food for more than 20 different animals, from grizzly bears to squirrels to Clark’s nutcrackers. They stabilize alpine slopes, slow snowmelt and reduce spring flooding.

But these important trees are dying by the millions across the West, thanks to bugs, disease, a century of fire control and a changing climate. Their future is so dim the federal government last week agreed whitebark pine deserves a spot on the endangered species list, though the government said it lacks the money to put it there.

So, researchers have been hunting down healthy trees, hoping to stall the decline by reproducing and replanting stronger trees. And one of the greatest crops of disease-resistant whitebark pines is around Mount Rainier.

“What we do is go out and collect cones off of trees and grow seedlings from those,” said Richard Sniezko, a geneticist with the U.S. Forest Service tree lab in Cottage Grove, Ore. “And of all the trees we’ve tested so far, the ones from Mount Rainier seem to have the highest disease-resistance found anywhere.”

Whitebark pine trees are unusual in that their seed cones don’t open. The trees only reproduce because Clark’s nutcrackers split open the cones with their long beaks and carry away the seeds, burying them in caches for later use. Squirrels, too, cut down cones and stack them up in piles, which are often raided by other wildlife, especially bears.

The trees are common throughout the northern Rockies, and are perhaps best known for providing late-season feasts for Yellowstone National Park grizzlies. But trees there are being wiped out by mountain pine beetles, which thrive in a warming climate and attack weakened trees.

But while less common in the Northwest, the trees play an important role in the Cascade Mountains, too, and are disappearing here just as fast, even though pine beetles don’t yet seem to be much of a factor.

“I would stop short of saying we don’t have mountain pine beetle problems,” said Gregory Ettl, a forestry professor at the University of Washington. “It could be here and we haven’t seen it, but so far we’ve escaped what’s happening in the Rockies.”

But here blister rust, a fungus brought over from Asia more than a century ago, has started clobbering trees. Blister rust produces cankers that eventually girdle trees and branches, killing them.

Between 2004 and 2009, the proportion of infected whitebark pines in Mount Rainier rose from 63 percent to 78 percent. “Within the last 10 years or so, blister rust has really ratcheted up in the frequency of infection,” said Diana Tomback, a whitebark pine expert and chair of the University of Colorado at Denver’s integrative biology department.

Not all infected trees die. And while mortality rates nearly doubled in North Cascades National Park during that time, they only crept up a little in Rainier.

No one knows precisely why Rainier’s whitebark pines, found largely near Sunrise, seem to have a greater ability to keep disease at bay. Sniezko suspects it may be that Rainier was hit by the blister-rust fungus years ago, and only the stronger disease-resistant crop was around to reproduce.

“As people eventually elucidate what genes are controlling this, we may discover that other things are going on, but right now we don’t really know,” he said.

But there’s no question that something at Rainier is different.

“We’ve gone up and down the Cascades,” Sniezko said. “When we did tests in Crater Lake and Mount Rainier, it was like night and day. Crater Lake had nearly 100 percent mortality. Mount Rainier had only about 50 percent.”

Still, even when blister rust doesn’t kill trees, it kills branches, destroying the tree canopy that attracts Clark’s nutcrackers. Scientists recently discovered that when trees produce fewer cones, fewer nutcrackers show up – which means fewer of the trees can reproduce.

“Nutcrackers are energy-efficient foragers; they don’t go places when they can’t get a food reward,” Tomback said. “So they become less inclined to hang around and disperse seed.”

That’s why efforts to grow trees and replant them have taken off in Oregon and at another research station in Idaho.

The programs are new, and only a few thousand acres of replanting have been attempted. But more is expected in coming years.

“The next trick will be to protect these parent trees from pine beetles,” Tomback said. “Beyond that we’ll just have to ride this thing out.”


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