The Chief Joseph Scenic Byway wends its way through the Absaroka Mountains in the Shoshone National Forest between Cody and the northeast gate of Yellowstone National Park along a route so beautiful that travel guides are known to proclaim the drive alone is worth a trip.
But in recent years a change has occurred along a stretch of the highway in a the Clarks Fork ranger district. The trees are dying.
An outbreak of spruce budworms, which despite their name attack Douglas fir, has ravaged trees in the area.
In response, the Forest Service plans to log about 2,000 acres in the Clarks Fork corridor to remove trees killed by spruce beetles, mountain pine beetles, Douglas fir beetles and most recently spruce budworm, which continue to thrive. The move will require an amendment to the Shoshone’s recently adopted forest management plan. As written, the document does not allow for any activity that would disturb the byway’s appearance — such as logging — unless the area’s scenery could be restored within a few years, said Amy Haas, silviculturist with the national forest.
Removal of the dead and dying trees will change the landscape for decades, despite a plan to help expedite recovery, Haas said. A draft environmental assessment calls for a project-specific amendment to allow the proposed timber harvest, she said.
In addition to curbing an unprecedented spruce budworm outbreak, the timber cut is intended to reduce fire potential, Haas said.
Spruce budworms, which eventually metamorphose into gray moths, are native to Wyoming. About every 20 years populations reach epidemic proportions. The last major outbreak on the Shoshone was in the mid-1980s, Kurt Allen, an entomologist with the Forest Service told Wyofile last year. Normally an outbreak lasts only one or two years. The current infestation on the Shoshone is about five years old though, and has impacted about 33,000 acres on the forest, Haas said. It appears to be deadlier than past outbreaks too.
“We normally don’t see dead trees like this,” she said.
Bug detection flights, where entomologists look for patches of insect-killed trees, showed a 30 percent increase in spruce budworm activity between 2015 and 2016, Haas said. Numbers for 2017 flights were not yet available, but more larvae and egg masses were found this summer on the forest, making it likely the bug population will continue to grow, she said.
The Clarks Fork area has remained the epicenter of the outbreak, with spruce budworm spreading out toward Deadman’s Pass.
Trees in the area are already sick and weak from past insect epidemics including the mountain pine beetle outbreak, Haas said. Douglas fir in the area grow so closely together that their crowns often interlock allowing the insects to move easily from host to host through sprawling fir communities. The spruce budworm is also capable of covering larger distances by using silk thread to float on the wind, hass said.
The conditions along the Clarks Fork corridor made it easy for the insects to produce the next generation. There was so much easy food, Haas said.
“This was kind of a perfect storm,” Haas said.
The affected area is too large to spray with insecticide and it would have to be sprayed each year, which isn’t cost effective, Haas said.
Logging is a better option as it will remove impacted Douglas firs, as well as dead trees left from previous insect epidemics. Thinning will reduce the spruce budworm’s food source, and help the remaining trees grow stronger by eliminating competition for resources. The trees left should become strong enough to withstand the rest of the outbreak, Haas said.
“We know we can’t stop something on a landscape level, but we are setting ourselves up for the future,” she said.
The timber harvest also will remove potential fire fuel near structures in the wildland-urban interface, Haas said.
The plan calls for planting new trees in areas where natural regeneration won’t be possible because so many trees are dead. The goal is to create a diverse and resilient landscape that will also help the corridor regain its beauty faster than it would otherwise. It will still take about 50 years, for the area to mature, she said.
Because of the scenic values of the area, the Forest Service will take extra measures and care in the harvest plan design to hide temporary roads from view and restore them immediately after the project is finished.
The plan also has to balance wildlife considerations. Logging would only be allowed certain times of the year to avoid disturbing grizzly bears. The plan is also careful to keep intact lynx habitat, Haas said.
There have been two public comment periods on the proposal. The first draft received about 20 comments that were split almost evenly between people supporting the logging and people wanting the area left as is, she said.
The most recent public comment period, which closed Dec. 14, received about 35 comments, also evenly split, she said.
The Forest Service could finalize the plan in April and start logging shortly thereafter. It will depend on the timber market, but Haas anticipated thinning would start late next summer or early fall.