Pine beetle kill slows in Wyoming forestsby Kelsey Dayton
— February 25, 2014
Results from the U.S. Forest Service’s recent aerial survey showing the slowing of the pine beetle epidemic in Wyoming isn’t necessarily good news. The slowdown is mostly attributable to the fact that many trees are already dead. “It’s not really a victory,” said Wyoming State Forester Bill Crapser.
The U.S. Forest Service and Wyoming State Forestry Division recently released results of the annual aerial forest health survey in Wyoming, showing the spread of mountain pine beetles in the past year. One key trend is the insect’s activity “has slowed dramatically” expanding by only 29,000 new acres, primarily in the southern Wind River Range on high elevation five-needle pine trees, such as whitebark and lodgepole pines.
The forest service began the aerial surveys in 1996 near the start of the mountain pine beetle epidemic, which has killed more than 3 million acres of trees in Wyoming so far. The information provides land managers current data to help guide management strategies and prioritize work on forests, said Bob Cain, regional entomologist with the U.S. Forest Service’s Rocky Mountain Region. “A lot of things are looking better because there are fewer hosts,” Cain said.
Pine beetles are native insects, and outbreaks are a natural part of the regeneration of the forest. The outbreak provides a chance for the forests to come back healthier. Many western forests are the same age due to logging when the West was settled, Cain said. As the forests regrow, patch cutting can help diversify the ages of trees in the forest making them less susceptible to pine beetle outbreaks in the future.
“Even though we’re losing old growth forests, it’s happened before,” he said.
The difference is, it hasn’t happened at this level, noted Crapser. The pine beetle epidemic began in Wyoming in the late 1990s and by the mid-2000s it had expanded across the state. The insects transformed the landscape by 2008 and made many realize the size of the epidemic was different than ever seen before, Crapser said.
Thirty years ago, Crapser heard professors say pine beetles never attack trees smaller than 7 inches in diameter. In some areas the beetles have been found in trees with diameters as small as 3.5 inches, he said.
The beetles also have moved into higher elevations. Historically whitebark pine trees weren’t threatened by beetles, but with drought and climate change the insects can survive at much higher elevations. Scientists have measured up to 90 percent mortality in lodgepole pines in some areas. “It will be a long time in those areas until you see solid lodgepole pine forests like we had,” said Crapser.
Unfortunately, cold snaps like the ones that hit the state this winter rarely kill the pine beetles anymore because they are so short. It takes weeks of continuous 20- to 25 below zero weather to kill pine beetles, which produce a type of antifreeze to protect them in the winter.
While the Medicine Bow, Bridger Teton and Shoshone National Forests were hit hard by the beetles, one area that escaped the devastation is the Big Horn National Forest. This year only 320 acres in the forest were infected by beetles. “They have gorgeous trees,” Cain said. Forest managers are trying to understand why the area has stayed healthy while they also use past experience to protect the forest if beetle activity begins to pick up in that area.
In the Black Hills, forest managers are suppressing pine beetles by thinning ponderosa pine, making the trees more vigorous. The strategy also spaces the trees farther apart thwarting the beetles from spreading tree-to-tree.
The dead forests pose new management challenges, changing the fire regime and wildlife patterns on forests, Crapser said. “We have to decide ‘What do we want our forests to look like 100 years from now and how do we get there?’” he said. Management tools include prescribed burns and salvage logging, he said. To help paint that 100 year vision, Wyoming Gov. Matt Mead created a task force to recommend ways to improve forest health across the state.
The U.S. Forest Service, according to a press release, has four 10-year contracts across the region to remove dead trees. In 2013, timber harvested from regional national forests totaled enough to construct 25,000 homes.
“Restoring forest health and resiliency is a top regional priority and is guiding the work on the forests,” Dan Jiron, regional forester for the Rocky Mountain region of the U.S. Forest Service, stated in the press release.
The future for Wyoming forests isn’t all bleak. Even in areas where many of the pine trees are dead, undergrowth plants are still thriving and some subalpine spruce is growing. “There is a lot of green still there,” Crapser said. “The forest isn’t destroyed. It’s still a forest. It’s just a different forest than we’ve ever seen.”
— “Peaks to Plains” is a blog focusing on Wyoming’s outdoors and communities. Kelsey Dayton is a freelancer and the editor of Outdoors Unlimited, the magazine of the Outdoor Writers Association of America. She has worked as a reporter for the Gillette News-Record, Jackson Hole News&Guide and the Casper Star Tribune. Contact Kelsey at [email protected] Follow her on twitter: @Kelsey_Dayton
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