Common (Translated Scientific) Name: Subalpine Fir - Engelmann Spruce / Rusty Menziesia / Common Beargrass Forest

Colloquial Name: No Data Available

Hierarchy Level:  Association

Type Concept: This association occurs throughout the middle to northern Rocky Mountains and on into the Canadian Rockies as a small- to large-patch type from mid to upper subalpine habitats. In the southerly portions of its distribution, the Wallowa and Seven Devils mountains and Idaho Batholith, it faithfully occupies moderate to steep slopes of northerly aspects at elevations ranging from 1700 to 2300 m (5600-7500 feet), but dropping to 1370 m (4500 feet) where frost pocket conditions obtain. Further to the north it also occurs predominantly on northerly exposures, but at higher elevations in wetter climates, it may be found on southerly exposures. It can occur on a given slope from the toe, up the backslope to the slope shoulder, and in wetter climates is found on ridgetops as well. It is perhaps most widely distributed in western Montana where individual stands may comprise hundreds to thousands of acres. It exhibits no particular substrate preferences being found on granitics, fine-grained sedimentaries (including argillite and limestone), metasediments, and mica-schist; volcanic ash caps of varying depths (to 50 cm thickness) are very prevalent in the southern and western portions. The predominant soil texture is silt loam, and soils are uniformly well-drained. Rock content of surface horizons ranges from about 15% to over 50%. This is a closed forest type for the most part with total upper canopy cover ranging upward from 60%. A variable mix of Abies lasiocarpa and Picea engelmannii dominates the canopy as well as the regeneration layers. Seral tree species do poorly on these sites; Pinus contorta, Pseudotsuga menziesii, and Larix occidentalis are the only tree species consistently present and seldom is their canopy cover as great as 20%. The modal condition for the undergrowth varies with geographic region. Menziesia ferruginea consistently dominates the tall-shrub layer, which may also have Alnus viridis ssp. sinuata as a conspicuous component. In all parts of the type''s range Vaccinium membranaceum is the mid (short) shrub dominant with coverages generally upwards of 30%; it is usually accompanied by low cover of Ribes lacustre and the somewhat shorter dwarf-shrub Vaccinium scoparium (or its ecological analogue Vaccinium myrtillus). The only graminoid consistently present, Luzula glabrata, occurs in slightly greater than trace amounts in stands at higher elevations and experiencing deeper snowpack. The herb layer, depauperate in comparison to that of ~Abies lasiocarpa - Picea engelmannii / Menziesia ferruginea / Clintonia uniflora Forest (CEGL005893)$$, is strongly dominated by Xerophyllum tenax; Arnica cordifolia, Arnica latifolia, Goodyera oblongifolia, Viola orbiculata, and Orthilia secunda are the only forbs approaching or exceeding 50% constancy.

Diagnostic Characteristics: No Data Available

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: This very extensive and abundant association is slightly changed in name and concept from several pre-existing syntaxa. This association bears the dual designation for the tree canopy because this in fact describes over 95% of existing stand conditions with dominance shared by either or both species (Abies lasiocarpa or Picea engelmannii). When either or both of these species comprise less than 25% of the uppermost tree canopy cover, then another association is indicated. This association is very similar to or identical with Abies lasiocarpa / Rhododendron albiflorum / Xerophyllum tenax (Williams et al. 1995); only Rhododendron albiflorum needs to be added as a co-diagnostic species of the tall-shrub layer (with Menziesia ferruginea). In a few cases Rhododendron albiflorum is the sole dominant of this shrub layer, but this fact does not perceptibly change the environmental parameters defining this type. The addition of Rhododendron albiflorum to the key would create an overarching type extending from Banff and Jasper south to central Idaho. It is suggested that individual indicator shrub species or their combined cover need to be 5% or greater to recognize the type described here. Xerophyllum tenax must also exhibit at least 5% cover; it has been added to the type name so as to distinguish this association from others characterized by Menziesia ferruginea and Rhododendron albiflorum dominance. These other associations represent yet more extreme environments.

Similar NVC Types: No Data Available

note: No Data Available