Physiognomy and Structure: No Data Available

Floristics: Although Abies grandis is present in all the tree layers, Pseudotsuga menziesii and Larix occidentalis are the dominant tree species in younger seral stands (Johnson and Simon 1985), while Abies grandis gains dominance in the understory (Pfister et al. 1977). Pinus ponderosa was found to be a dominant seral species in Idaho and Montana. Old-growth stands are almost completely dominated by Abies grandis with only a few old specimens of Pseudotsuga menziesii, Larix occidentalis, and Pinus contorta. Abies lasiocarpa and Picea engelmannii are occasional species at the upper elevational limits of the type. The shrub layer is dominated by Linnaea borealis, which often forms an extensive mat on the forest floor. Vaccinium membranaceum occurs where canopy openings permit light to filter to the forest floor. Other common shrubs are Rosa gymnocarpa, Lonicera utahensis, and Chimaphila umbellata. In the herbaceous layer, sedges are often found. Carex geyeri, Carex concinna, and Carex rossii are all commonly present. The most frequent indicator forbs are Osmorhiza berteroi (= Osmorhiza chilensis), Galium triflorum, Prosartes trachycarpa (= Disporum trachycarpum), and Goodyera oblongifolia. Forbs with a high cover value are Viola orbiculata and Thalictrum occidentale. Moehringia macrophylla (= Arenaria macrophylla), Fragaria vesca, Fragaria virginiana, and Vulpia octoflora (= Festuca octoflora) increase when a site is disturbed. Cynoglossum officinale and Urtica dioica are found when sites are heavily degraded.

Pfister et al. (1977) describe two phases for this type in Montana. The first, a Linnaea borealis typic phase, is the most common, ranging from 1130 m (3700 feet) to above 1400 m (4600 feet) on northerly aspects. The second phase is a Xerophyllum tenax - Xerophyllum tenax phase, appearing to be transitional between the Linnaea borealis phase and the Abies grandis/Xerophyllum tenax habitat type. This Xerophyllum tenax phase occurs on easterly to southeasterly aspects between 1435-1675 m (4700-5500 feet).

Steele et al. (1981) describe three phases for this association in Idaho: the Linnaea borealis typic phase found in mountains nearest the Oregon border; a Vaccinium globulare - Vaccinium globulare phase, reflecting some of the cooler conditions with more Picea and Abies lasiocarpa as well as Vaccinium membranaceum dominating the understory; and a Xerophyllum tenax - Xerophyllum tenax phase occurring only as a minor phase where there was less Picea than the Vaccinium globulare phase and more Pinus ponderosa and Pseudotsuga, and Xerophyllum tenax as an additional component.

Cooper et al. (1991) describe two phases for this type in northern Idaho, a Linnaea borealis phase and a Xerophyllum tenax phase. The Xerophyllum tenax phase is found at higher elevations (>1500 m [4900 feet]), usually on southerly aspects. Pinus contorta and Pseudotsuga are the primary seral species. The Linnaea borealis phase shows the typical characteristics of the association, with Pinus ponderosa increased in importance and Picea decreased in comparison to the Xerophyllum tenax phase.

Dynamics:  Indian paint fungus, root rots, atropellus, western gall rust, spruce bud-worm, tussock moth, fir engraver beetle, and mistletoe are not uncommon, yet they do not appear to cause extensive damage in stands. There is potential for bark beetle attacks in Pinus contorta and Larix occidentalis under growth stress.

Abies grandis is susceptible to fire and will get root damage from surface fires if duff burns deep. Heart rot can be introduced through fire scars. Pinus contorta stands result from stand-replacement fires. Larch can form pure stands following fire (Johnson and Simon 1985).

Fire hazard is normally low to moderate under normal weather conditions (Fischer and Bradley 1987). This type falls into Fisher and Bradley''s Fire Group Eleven - warm, moist grand fir, western red-cedar, and western hemlock habitat types for Montana. The threat of fire is highest in the summer, when the moist maritime climate no longer prevails. During severe summer drought, heavy fuel loading from high plant productivity can set the stage for severe, widespread fires. Stands are replaced and sites revert to pioneer species. Summertime fuel moisture conditions in young stands are not nearly as high as in older, more dense stands, and the effects of fire are often more severe than they are in older stands. Surface fires often scar the base of the grand fir, creating favorable entry points for decay organisms. The initial floral component, seeds stored on site, and the accidents of natural seeding and seedling establishment may structure the community following the fire more than the characteristics of the fire itself. Although generally true for all fire groups, it is more pronounced in this fire group. The use of fire for site preparation will usually result in increased spring and summer browse for big game in addition to successful regeneration of seral tree species.