10-05- 2016 - CHEYENNE – The mountain pine beetle outbreak that spanned almost two decades is all but over locally, but dead and dying trees remain.

Since the outbreak’s beginning in 1996, the pine beetle has killed thousands of mature lodgepole pine trees across Wyoming, Colorado and other Rocky Mountain states.
But as the beetle has run into fewer trees to attack, the outbreak has subsided.
“The mountain pine beetle epidemic for Medicine Bow-Routt National Forests has basically run its course,” said Mark Westfahl, a timber program manager for the national forests and Thunder Basin National Grassland.
Westfahl said evidence from aerial surveys shows the number of acres affected by pine beetles has decreased.
On Medicine Bow National Forest land, which covers the Laramie, Snowy and Sierra Madre ranges, Westfahl said 1,700 new acres of timber were affected by the beetle outbreak in 2015.
That compares to a total of 681,000 acres affected from 1996 through 2015.
On Routt National Forest land, which is in northern Colorado around Steamboat Springs, no new land was affected by the pine beetle in 2015, and a total of 613,000 acres have been affected since 1996.
Medicine Bow National Forest totals about 1.1 million acres, and Routt National Forest totals about 1.125 million acres.
The mountain pine beetle is native to the region and was able to have a population outbreak due to mild winters and low precipitation.
But after feasting on trees for 20 years, the insects are running out of food.
“They’ve probably eaten up the trees they’re going to attack,” Westfahl said.
The Forest Service has been tackling the issue of dead trees for several years, and has been clearing dead trees from roads, campgrounds and other recreation areas.
The Forest Service has also made use of stewardship contracts to clear dead trees from areas people use, Westfahl said.
“We now have a landscape that has hundreds of thousands of trees on it, and those trees are beginning to fall down,” he said.
Another beetle responsible for tree deaths, the spruce beetle, has subsided in Wyoming, though Colorado is still being markedly affected.
Westfahl said 750 new acres affected by spruce beetle were found on Medicine Bow National Forest land in 2015, bringing the total to 118,000 acres affected since 1996.
Meanwhile, 8,000 new acres affected by spruce beetle were found on Routt National Forest Land, bringing the total to 176,000 acres affected since 1996.
The dead trees also contribute somewhat to the potential for forest fires, though to varying degrees as they pass through the stages of death.
“The fire danger goes up and down through that whole cycle,” Medicine Bow-Routt National Forests spokesman Aaron Voos said.
When the trees initially die, their needles dry out and turn red, known as the “red phase,” making the tree very flammable.
The needles then begin to fall and the tree enters a “gray phase,” and fire danger is reduced.
Eventually the tree will fall, increasing fire danger once more.
“It’s not that it’s more flammable, it’s that it would burn hot” on the forest floor, Voos said.
Finally, the tree will rot, and the fire danger drops again.
Of course, fires are also strongly influenced by other factors, like dry weather and wind, and living trees can burn quickly under the right conditions.
Research as to if and how the mountain pine beetle contributes to the threat of forest fires is ongoing.
The pine beetle didn’t hit the entire forest at once, creating different levels of tree death throughout the region.
Voos said that in general, the worst of the beetle outbreak chronologically moved north into Wyoming from Colorado, and the Pole Mountain Unit of the Medicine Bow National Forest was one of the last areas to get hit hard by the beetle.
Regardless, forest users need to be mindful of their surroundings when visiting the forest, Westfahl said.
Don’t camp or park a car near dead trees, and be aware of their location when engaging in other activities.
“Just be aware of your surroundings,” Westfahl said.
The Medicine Bow-Routt National Forests and the University of Wyoming have collaborated to create a website, www.beyondbarkbeetles.org, for more information about the effects of the outbreak.