Bitterroot Forest Mountain Pine Beetle Infestation Increases
The bad news from this week’s joint news release from the US Forest Service and Montana Department of Natural Resources and Conservation – “Mountain Pine Beetle activity in the Bitterroot is increasing.”
Over a million acres in the Bitterroot Valley have been killed or defoliated by insects – the main culprit is the mountain pine beetle. Also increasing its activity is the Western Spruce Budworm, which has visited the local forest before. The budworm has affected over 1.5 million acres statewide. In Ravalli County, the budworm defoliation has doubled from 2011 to 2012, with the report noting areas east of Corvallis.
Elsewhere in Montana, the bark beetle activity seems to be on the decline, according to USFS forest pathologist Greg DeNitto, except for the Bitterroot Mountains and the Anaconda Range.
In the Bitterroot, mountain pine beetle activity has doubled for lodgepole pine and ponderosa pine. The report said the activity “increased nearly 12 fold in high elevation five-needle pines. Other areas of note were the West Fork, Lake Como, Lost Trail Pass and along the Bitterroot River. The beetle is not too picky, either, attacking trees from 3 inches in diameter to as large as 29 inches in diameter.
The estimated acreage of defoliation and mortality is 1,071,976 acres on national forest land, 120,837 acres of private land and 27,009 acres on state lands, with no end in sight. In fact, the report said “mountain pine beetle is expected to continue on this increasing trajectory as long as suitable host trees remain and barring any unusual weather event.”
The figures come from aerial surveys of the USFS and the Montana DNRC.