Beginning in the late 1990s, the pine forests of Montana began to experience the largest mountain pine beetle outbreak in recorded history. Large swaths of forests began to turn red, then gray as the beetles ate their way through Pacific Northwest stands.
At their peak in 2009, this native insect infested nearly 3.7 million acres statewide, leaving dead or dying trees in their wake. The infestation became a hot topic not only among those concerned with forest management, but also among the wood products industry. By 2014, pine beetle numbers began to decline with new infestation totaling about 600,000 acres.
A majority of the trees killed were lodgepole pine, but the beetle also killed ponderosa pine--both commercially important tree species in Montana. During the height of the epidemic approximately 7.4 billion cubic feet of timber were affected.
The impact of the mountain pine beetle on the forest products sector has been high and continues to affect wood supply. Dead or dying stands still spot the landscape and the longer these trees remain unharvested, the less useful they become.
In 2014, the Montana forest products industry converted 93.1 million board feet of lodgepole pine and 69.4 million board feet of ponderosa pine into lumber, house logs, pulpwood, posts and poles, log furniture and industrial fuelwood. However, sawmills across the state were only operating at 62 percent capacity, partially due to a timber supply shortage caused by the beetle.
As the epidemic has slowed, new data address the financial impact of the beetle on Montana's forest products industry. The data quantify changes in log quality, grade, value, volume, product mix and costs across the supply chain.
It begins when a tree is attacked. Initially, the tree responds with biochemical and physical defenses, including secondary resin accumulation at wound sites. But damage by the beetle to the living tissue and the introduction of fungi that spreads across the sapwood can disrupt the transport of water and sap, killing the tree.
Trees that do not survive move through a series of visually distinct stages--green, red and gray--from live to dead, with parallel and increasing tree damage from a commercial value perspective.
During the first year following an attack; water flow slows and stops. The needles tend to retain some moisture and remain mostly green. During this stage, trees retain most of their commercial value. Some will survive an attack by...