Introducing . . . Denim Pine

Cascadia’s inland pine forests have been, predictably, catching fire a lot this summer. (From the safety of a boat, I came within a couple hundred yards of a giant blaze on my vacation earlier this month.) And climate change has likely fanned the flames.

But climate change’s biggest toll on inland forests, so far, has been to turn them blue – the color, not the mood or the political leaning.

Yes, trees in the inland Northwest, especially in British Columbia, are increasingly stained in azure shades. The explanation is such a perfect example of ecological interactions that, like foxes and rabbits, it might start appearing in biology textbooks.

Inland pine forests have long been kept honest by a few types of bark beetles, the mountain pine beetle (pictured) among them, which attack trees that are stressed by drought or disease. Hitchhiking on the voracious wood eaters’ backs is often a fungus. The beetles bore through pine bark to eat and lay their eggs; the fungus spreads inside the bark. Where the fungus goes, it dyes the wood in shades from cerulean to indigo. Together, fungus and beetles weed out stressed stands of trees. This gives the forests a healthy mix of ages, which makes them more resistant to catastrophic fires and disease.

These self-balancing feedback loops, of course, evolved within the bounds of the present (or recent past) climate. As Cascadia’s climate changes, the ecosystem is coming unglued. Beetle numbers are limited by, among other things, the coldest days in winter. And, though average temperatures in our region have increased only a little as yet, the extreme colds have become much less extreme. In British Columbia, for example, where mountain pine beetles are most prevalent, average year-round temperatures are up about 1 degree Fahrenheit over the past century. Minimum winter temperatures, meanwhile, are up more than 4 degrees (pdf, see page 6).

In places, reports the High Country News (subscription required) in an excellent feature, the winter die-off rate among beetles has dropped from about 80 percent to about 10 percent.

Adding fuel to the fire, interior Cascadia has suffered one summer drought after another in the past decade, also perhaps because of climate change. And drought has weakened the pine forests’ resistance to beetle attack. Augmenting the effects of climate, decades of forest fire suppression and clearcut logging have homogenized vast areas of forest to even-age stands of middle-aged lodgepole pine—setting the table for a bioregion-wide beetle fest.

Bark beetle numbers in the inland Northwest are up by the hundreds of millions, perhaps even billions. Talk about a population boom!

As of late last year, mountain pine beetles had spread across 25 million acres of British Columbia’s timberlands, plus millions of additional acres of parks and other protected forests. (Their 2003 extent is here. An animation showing Mountain pine beetle outbreaks in British Columbia in recent decades is here.) And beetle infestations seem to be accelerating. BC beetles overran twice as large an area in 2003 as in 2002.

In the Northwest states, beetles are also proliferating. Trees by the millions have dried out and died in Idaho’s national forests. Eastern Washington has lost a third of a million acres of lodgepole pine.

Unfortunately, there’s some even worse news: the beetles, emboldened by their success among lodgepole pines, are moving into new, unprepared hosts. In Idaho and Washington, the infestation has spread up to the whitebark pines, a high altitude species that plays a critical role in its ecosystem. In 2003, some 13,000 acres of whitebark pine died in eastern Washington, up from 1,700 acres the previous year.

Whitebark pine nuts are a seasonal food for grizzly bears. When the number of nuts is low, bears move to lower elevations, where people usually live. Research conducted in Yellowstone National Park found that bad Whitebark nut years are big years for human-bear interactions. And human-bear interactions lead to one thing: dead bears. Biologist David Mattson told the Billings (Montana) Gazette "When you have a good year with whitebark pine, the bears stay up high and stay alive. When you have a poor year, the bears come (to lower elevations) and they die faster." Beetles, in short, endanger grizzly bears.

Oh, and about the blue wood: With millions of acres of tinted trees dying in the hinterlands, the province of British Columbia has launched a marketing campaign to help sell the lumber. Their bold, lemons-to-lemonade concept? Denim Pine.

Here’s the pitch:

Denim Pine is a unique exotic wood created by Mother Nature. It can currently be found deep within the forests of British Columbia, Canada.

Only Denim Pine products guarantee they are environmentally friendly. You will also know you are buying "Green". These trees died naturally in the forest.

Can “acid-washed boards” be far behind?

(This post researched and coauthored by Matt Schoellhammer.)