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Beetles, Disease Hurt Whitebark Pine’s Chances of Survival

BY Admin  December 19, 2008 at 11:39 AM EDT

Whitebark pine beetle damage; Photo U.S. BLM

Now, with deaths increasing rapidly across its habitat, a coalition of scientists is trying to get the whitebark pine onto the endangered species list. Last week, the Natural Resources Defense Council formally petitioned the Interior Department to add the tree to the list.

The push stems from fears that the tree’s extinction could have ripple effects throughout the environment. Scientists believe it could lead to increased grizzly bear attacks, because the tree’s fatty nuts provide food for grizzlies. Without them, the hungry bears are forced to forage at a lower altitude, increasing the risk of attacks on humans. The nuts also feed other birds and small mammals.

Scientists also fear that the trees demise will leave land more vulnerable to flooding — the pines’ thirsty roots to suck up water, and its limbs shade snow that would otherwise melt too quickly in the spring.

Mountain pine beetles and a fungal disease called blister rust are both destroying the trees. Ecologists believe problems with the whitebark pine began in the late 1800s, when blister rust first arrived in the Vancouver, Wash., area. It has since spread throughout the entire region of the tree’s habitat.

In recent years, the already struggling tree has been faced with another challenge: the mountain pine beetle. Until recently, the frigid, high-altitude habitat of the whitebark pine was too harsh for the more fair-weathered beetle. But as the climate warmed, the beetles slowly began foraging at higher altitudes.

“The weakened state from blister rust makes them more susceptible to beetle infections,” said Sylvia Fallon, an ecologist and staff scientist with the Natural Resources Defense Council. “This combination of factors has really crippled the whitebark pine across its range.”

In 1999, it was uncommon to see reddened whitebark pines, she added. “By 2007, it’s really shocking how you see entire forests turned red.”

The problems are not unique to the whitebark pine. Other trees, such as the lodgepole pine, are common victims of mountain pine beetle attacks. But lodgepoles have evolved over the years to develop a resistance against the beetle. When attacked, the tree releases a chemical that is toxic to the beetle. The whitebark pine lacks such a defense system and the trees do not reproduce quickly. In fact, the whitebark pine typically doesn’t even begin bearing pinecones until it’s as old as 80.

“John Muir cut down a six-inch whitebark pine in the Sierras, and was astonished to find that it was 426 years old,” said Jesse Logan, an insect ecologist and former research scientist with the U.S. Forest Service. “They’re not all that slow-growing, but it’s a slow-growing species.

Adult beetles bore into the trees’ nutrient-transporting phloem tissue that lies under the bark. Beetles attack the tissue while laying eggs, halting the transport of vital nutrients from needles to roots.

“Needles are the photosynthetic factory of the tree, and by essentially clogging up and short-circuiting the phloem tissue, none of this gets down to the roots,” Logan said.

Research shows that some of the trees do have a natural genetic resistance to blister rust.

“If we could identify trees that exhibit a natural defensive response, we can protect the trees,” he said.

Scientists hope that listing the species as endangered will trigger funding for research to better understand the disease and possibilities for resistance, as well as other strategies to protect the struggling tree. The tree needs more attention, resources and close monitoring, Logan said.

“Endangered species listing requires a recovery plan,” Fallon said. “We hope it will bring the necessary attention and resources to implement a strategy for restoring the species. We hope it will give us the support and resources needed to keep the species from going extinct.”