This is a blog about the native conifers of the Pacific Northwest. It is a companion to the Northwest Conifers site. The blog will focus on timely and interesting details about our conifers, their connections to the rest of the environment, and our connection to them.

Saturday, January 13, 2018

Focus on Subalpine Fir

As its name suggests, subalpine fir is a high elevation tree that often grows at the timberline. It may not be the tallest of the firs, but it is arguably the most stately. It is easily recognized by its slender, spire-shaped form, a clever adaptation to heavy snowfall. Longer branches would break under the weight of the snow. It is a picturesque accessory to the majestic alpine scenery, where you can see it framing your view of snow-capped mountains. Below the timberline, it can grow to over 150 feet (45 meters).

You can easily identify subalpine fir by the needles, which curve upward and have bands of white stomatal bloom on both sides, two on one side and one on the other. Pacific silver fir and noble fir also grow near the timberline, but Pacific silver fir has stomatal bands only on the lower side of the needles, and noble fir has straight needles with a sharp curve where they attach to the twig. At the timberline, subalpine fir hangs out with mountain hemlock, notable for its drooping top. You are also likely to see whitebark pine nearby, distinguished by its bundles of five needles.

The cones sit upright on branches near the treetop and fall apart at maturity, dispersing both seeds and scales, and leaving a cone core spike on the branch. The cones often ooze a white resin.

Subalpine fir grows in the Cascades, Olympics, and the mountains of northeast Oregon and Washington. It also grows throughout the Rocky Mountains and ranges from Arizona to Alaska. It grows from 4000 feet to the timberline in the Pacific Northwest, to 12,000 feet in Arizona, and down to sea level in Alaska. Although subalpine fir is moderately shade-tolerant, it does not compete well with other Northwest conifers when it is growing in the shade. You often see it in or around the edges of open meadows. 

The seedlings of subalpine fir grow slowly, often growing just an inch in a year. But these trees have a creative alternative way to reproduce at higher elevations. The lower branches of trees can be pressed to the ground by heavy snow and grow roots where they touch the ground. This process, called layering, creates mats of tree branches. Trees will also sprout and grow from these mats, producing islands of subalpine fir trees. 

As the climate warms, subalpine fir will be able to move to higher elevations, especially in wet areas. Warmer temperatures have already enabled the firs to invade some alpine meadows to the consternation of wildflower lovers. However, lower elevation trees may not be able to tolerate the warmer and drier conditions. This may seem like an even trade for the subalpine firs, but it is not. Due to the usually conical shape of Cascade Mountains, the higher elevation area is much less than the area at lower elevations.

While it has few commercial uses, subalpine fir is an important component of the subalpine forest community, providing habitat for animals and protecting watersheds that collect our drinking water. Although not readily available at local Christmas tree lots, it would make a shapely Christmas tree. It’s a long distance to go for a Christmas tree, but you can find subalpine fir in Norway, where it is becoming a popular “exotic” species for Christmas tree production. Locally, you can find cultivars of subalpine fir at nurseries, especially dwarf cultivars. 

The scientific name of subalpine fir is Abies lasiocarpa. The species name, lasiocarpa, means "hairy fruit," a reference to the fuzzy cones. Other common names: alpine fir, white fir, balsam fir, and Rocky Mountain fir. 


See also

The Gymnosperm Database
Christmas trees in Norway
Vegetative Reproduction by Layering
Climate change and subalpine fir:
    Growth response in the Olympic Mountains
    Subalpine fir in meadows
    Predicted range maps of subalpine fir