Common (Translated Scientific) Name: Subalpine Fir - Engelmann Spruce / Common Beargrass - Smooth Woodrush Woodland

Colloquial Name: No Data Available

Hierarchy Level:  Association

Type Concept: This association is broadly distributed throughout the mid to upper subalpine zones of the northern Rocky Mountains, concentrated in northern Idaho and western Montana and extending into the Canadian Rockies of southwestern Alberta. The demonstrated elevation range is from 1555 to 2135 m in the northern portion of its distribution and 1740 to 2380 m in its southern occurrence. It is strongly associated with moderate to steep warm slopes, usually having a southeast- through south- to west-facing exposure, usually occurring from midslopes upwards to slope shoulders and occasionally extending to high-elevation benchlands as well. It is characterized by having relatively heavy snowpack that persists well into the growing season. These sites have well-drained soils derived from a host of parent materials, including volcanics (granitics, andesite, rhyolite) sedimentaries (limestone, dolomite, siltstone), metamorphics (quartzite, argillite, gneiss, mica-schist) and metasediments. The range in soil surface texture is broad, from silty clays to sandy loams with the gravel content averaging about 30% near the surface and increasing markedly with depth. These are very open woodland sites with the tree component often occurring as scattered clumps and, at the highest and coldest extremes, approaching a krummholz form with trees as short as 5.5 m (18 feet) in height when mature. The canopy is generally strongly dominated by Abies lasiocarpa followed distantly in order of decreasing average cover by Pinus albicaulis, Pinus contorta, and Picea engelmannii (this order may change slightly by region and is undoubtedly due to differences in type and severity of disturbance). The undergrowth component is species-poor. Tall shrubs are virtually unrepresented, and the short shrubs Vaccinium membranaceum and Lonicera utahensis have high constancy but only the former has coverage exceeding 5%. The dwarf-shrub component has only two constant species, Vaccinium scoparium and Vaccinium myrtillus, only one of which exhibits high cover in a given location; Phyllodoce empetriformis may be a conspicuous component but its presence is very inconsistent. The graminoid component is singularly dominated by Luzula glabrata with a cover of 5 to 20% (extremes to 50 or 60%, where Xerophyllum tenax cover is low); Carex geyeri is a common component only in central Idaho representation of the type. Xerophyllum tenax is almost invariably the dominant herb, joined by a number of other forbs, none of which express high constancy.

Diagnostic Characteristics: No Data Available

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: This type has been variously defined and identified throughout the middle and northern Rocky Mountains. Both Abies lasiocarpa and Picea engelmannii may be canopy dominants and almost invariably dominate the reproductive layers as well. The presence of significant amounts of Luzula glabrata var. hitchcockii (greater than 3% approximately) is considered indicative of these upper subalpine habitats that receive a long-persisting snowload. The phase level communities previously identified (Steele et al. 1981, Cooper et al. 1987) were considered significantly distinct environmentally and compositionally to be accorded association status.

Similar NVC Types: No Data Available

note: No Data Available