Montanans have grown accustomed to seeing forests turn from green to red to gray as a mountain pine beetle infestation works its way across the landscape.

A new survey of sawmill owners in the state now shows what that means to the bottom line of the timber industry. Put simply, the value of a pine tree falls right along with its needles.

“The longer you wait, the less value the landowner will get out of it,” said study co-author Dan Loeffler of the University of Montana’s Bureau of Business and Economic Research. “We’re not giving advice. We’re just quantifying how the industry views these trees.”

Together with Nate Anderson of the U.S. Forest Service Rocky Mountain Research Station in Missoula, Loeffler looked at what the beetle infestation did to the wood supply chain. It turns out the rice-grain-sized bugs affect everything from the chance of a tree breaking when the logger cuts it down to the reduction in price when the resulting 2x4 comes out stained blue by a fungus that comes along with the beetle attack.

“We hope we can take this information from the Montana supply chain and learn from that,” Anderson said. “This affects everything from land management to the operation and logistics of the mills. That way we might be in a better position for the next outbreak.”

The current mountain pine beetle outbreak got started in the late 1990s. At its peak in 2009, it affected 3.7 million acres a year. The infestation has slowed down considerably since then. Surveys done in 2014 showed about 600,000 acres affected.

Montana has about 25.9 million acres of forest. The study notes that while the state has lots of federally protected wilderness areas, 84 percent of that forest total is unreserved. Nearly 20 million acres are classified as timberland open to logging.

Lodgepole and ponderosa pine stands make up about 27 percent of Montana’s forest. In 2014, that produced 162.5 million board-feet of lumber, house logs, pulpwood, post/poles, furniture and hogfuel (wood waste used in sawmills for heat and electricity).

While 32 sawmills were still active in 2015, the survey only covered the six largest. That group turned out 69 percent of the total statewide lumber production — 371 million board-feet. That’s enough lumber to build almost 227,000 average-sized homes.

Mountain pine beetles are native to Montana forests, and outbreaks have occurred many times in the past. Nevertheless, the survey found mill owners have become leery of beetle-killed wood.

“Several mills involved in this survey, as well as loggers and truckers in Montana and other parts of the Rocky Mountain region, specifically avoid MPB (mountain pine beetle) timber,” the authors wrote, because green wood is worth so much more.

“This makes it difficult for forest managers to employ silvaculture not just to recover timber value, but also to achieve other objectives such as reducing fire risk and protecting infrastructure and recreational opportunities. This effect can be intensified if beetle-kill stands that would otherwise be harvested are not even considered for harvest because administrative procedures (like NEPA compliance) would delay harvest enough to degrade products to the point that revenues do not cover costs,” they wrote, referencing the National Environmental Policy Act.

Anderson and Loeffler stressed that the study does not assume that every beetle-killed tree will go to a sawmill. Dead timber also provides habitat for wildlife and returns nutrients and moisture to the soil. It might be cut and burned for hazardous fuels reduction. Other research looks at the environmental impacts of bug infestations. This study catalogs the economic effects.

As beetles drain the life out of a tree, they also suck out its value. Once the infestation takes hold and the pine’s needles turn from green to red, the stumpage price of the tree drops 35 percent. After those red needles fall, the price drops another 46 percent. Most of the infected stand transforms from sawlogs to pulpwood.

That’s because the dead trees break more easily during logging and transport, fill with cracks and rot that lower the resulting boards’ quality, and become so dry that they cause equipment to jam. Coincidentally, the dead-dry trees fill up log and chip trucks with more volume than weight, meaning the trucker gets paid less than a load of live wood would earn on the scales at the mill yard.

“We value trees for many reasons,” Anderson said. “Some are financial, like forest products. But there are also aesthetic values, water supply values, and spiritual values. For land managers to effectively manage, we must have good information how different conditions affect those values.”