Physiognomy and Structure: No Data Available

Floristics: Stands in this association are predominantly uneven-aged. Abies grandis is the indicated climax tree species and dominates both the overstory and understory in old-growth stands (Johnson and Simon 1987). Pseudotsuga menziesii and Picea engelmannii act as secondary seral dominants, with spruce in virtually all age classes in old-growth stands. Pinus ponderosa, Larix occidentalis, and Pinus contorta are the primary invaders of severely disturbed sites. Seral tree success is related to region and phase (Cooper et al. 1987). By the time a pole-sized stand has developed, Abies grandis is generally the only tree species that continues to reproduce beneath the forest canopy (Pfister et al. 1977). In the shrub layer, Vaccinium membranaceum (= Vaccinium globulare) or Acer glabrum dominate the undergrowth. Vaccinium membranaceum (twice as abundant in early-seral stands), Rosa gymnocarpa, Lonicera utahensis, and Linnaea borealis are often abundant in this type. Clintonia uniflora accompanies a mixture of moist-site forbs in the herbaceous layer. Some moist-site indicators commonly present are Bromus vulgaris, Adenocaulon bicolor, Maianthemum stellatum (= Smilacina stellata), Coptis occidentalis, and Prosartes trachycarpa (= Disporum trachycarpum). Other species components are Carex rossii, Galium triflorum, Fragaria vesca, Thalictrum occidentale, Orthilia secunda (= Pyrola secunda), and Viola orbiculata.

Pfister et al. (1977) recognize three phases for this type in Montana. The first, the most extensive phase, is the Clintonia uniflora typic phase located below 1370 m (4500 feet) which exhibits the characteristics of the type. The second phase is an Aralia nudicaulis - Aralia nudicaulis phase found on low bottomlands near 915 m (3000 feet) and moist benches. Picea and Betula papyrifera are more common in this phase than the others, and undergrowth is more luxuriant. The last phase is the Xerophyllum tenax phase which is found at higher elevations between 1100-1525 m (3600-5000 feet), where it occupies relatively cold and well-drained sites. Abies lasiocarpa is more common in this phase, where Pinus ponderosa is usually absent. Environmentally, this phase appears to be intermediate between the Clintonia uniflora phase and the colder Abies lasiocarpa series.

Cooper et al. (1991) recognize five phases for Idaho: a Clintonia uniflora typic phase, a Menziesia ferruginea - Menziesia ferruginea phase which is indicative of the coldest sites within the type, a Taxus brevifolia - Taxus brevifolia phase where Taxus is abundant, a Xerophyllum tenax - Xerophyllum tenax phase which differs in the undergrowth by the dominance of Xerophyllum in a forb layer of reduced cover and species diversity, and a Physocarpus malvaceus - Physocarpus malvaceus phase which represents the warmest, driest portion of the type predominating on exposed south-facing slopes, with Tiarella trifoliata conspicuously absent.

Dynamics:  Damping-off fungus takes a heavy toll of Abies grandis seedlings during wet seasons, and insolation and drought cause mortality during the dry summer months. Indian paint fungus (Echinodontium tinctorium) may be very common on grand fir within this type (Pfister et al. 1977). Larix occidentalis can be subject to attack by the dwarf mistletoe parasite.

Fire hazard is normally low to moderate under normal weather conditions (Fischer and Bradley 1987). Although this type does not occur in Fischer and Bradley''s study, this type is equivalent to their Group Eleven - warm, moist grand fir, western red-cedar, and western hemlock habitat types. 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.

Severe disturbance by fire may result in dense homogeneous stands of lodgepole pine, Douglas-fir, and larch. More frequently, Douglas-fir and larch invade disturbed sites as small fire seral communities within relict grand fir stands. Spruce and Douglas-fir often form a fire sere prior to grand fir dominance. Big huckleberry, spiraea, pinegrass, elk sedge, and strawberries will all increase on these sites following fire. These rhizomatous plants may compete with regenerating trees though not detrimentally in this type (Johnson and Simon 1987).