The latest mountain pine beetle infestation appears to be slowing down in Eastern Oregon, but not before becoming the leading killer of the signature tree of Crater Lake National Park — the whitebark pine.
Park botanist Jennifer Beck says the beetle now kills more of the gnarled trees that grace the highest elevations of the park than an invasive fungus called white pine blister rust that also attacks them.
“The older trees they are attacking are centuries old,” said Beck. “They are often the biggest cone producers. This impacts regeneration and probably some food for wildlife.”
Countless park visitors have been told the story by rangers of how the whitebark pine depends on the Clark’s nutcracker to regenerate. The bird opens the trees’ cones to get the seeds, and buries them in underground caches for the future. But the birds often forget where they leave the seeds, which sprout before they are eaten.
Now Beck estimates as many as half of them are dead from the combined effects of the beetle and the fungus.
Wide swaths of lodgepole pine have also been turned from green to red by the insect. Park Superintendent Craig Ackerman says timber fallers are cutting dead trees around campgrounds, where they pose a safety hazard, but elsewhere in the park the infestation is considered part of the natural process.
The park is trying to protect whitebark pines by stapling them with a packet that emits an odor telling beetles that this tree is full, and they should find another tree to feed on.
Park personnel feel it is proper to take this unnatural step because the blister rust that makes the whitebark pine more vulnerable to beetle attack is not a native of North America, having come from Eurasia, Ackerman said.
As long as the dead trees have their needles, they are a fire hazard, but once the needles fall off after a couple years, they are no more likely to burn than living trees, Ackerman said.
The whitebark pine is a candidate for protection under the Endangered Species Act. The U.S. Fish and Wildlife Service has found that it deserves protection, but the agency does not have the resources to deal with it right now. Threats include the blister rust, pine beetles, wildfire and wildfire suppression, and climate change. The tree has been declining even in areas once thought immune from those threats.
As bad as the beetle infestation gets, things don’t look so bad as forests in the Rockies, because many of the forests around Crater Lake are a mix of species, such as mountain hemlock, which is not attacked by the beetles or the blister rust, Ackerman said.
Unlike Northern Canada, where beetle infestations appear to have been promoted by global warming, Oregon has seen periodic infestations for more than a century, said U.S. Forest Service entomologist Andris Eglitis. The cycles appear to be tied to the prevalence of mature lodgepole pine trees, the insects’ favorite food. Infestations have been recorded in the 1980s, the early 1900s and the 1840s.
At the peak of this latest infestation, in 2007, about 1 million acres of forest were under attack, Eglitis said. That is about half the area during the peak of the 1980s.
But it is still complicating efforts to protect whitebark pine, which are commonly seen around the rim of the lake, on Mount Scott, and on the highest cinder cones, said Beck. The park has been planting seed from trees that are resistant to blister rust, but many of them have since been killed by the beetles. Beetles have been seen in whitebark pine in the park since 2007, and the insects became the leading cause of mortality in 2009, she said.
“We keep hoping to see signs of it slowing, but what we see so far this summer is it is ongoing,” Beck said.