Common (Translated Scientific) Name: Mountain Hemlock - Pacific Silver Fir - Alaska-cedar Wood Group

Colloquial Name: North-Central Pacific Mountain Hemlock - Silver Fir Woodland

Hierarchy Level:  Group

Type Concept: This forested group occurs throughout the mountains of the North Pacific, from the central Cascades of Oregon north to the upper slopes of mountain ranges along the Gulf Coast of Alaska, to the Cook Inlet. It is the predominant forest of subalpine elevations in the coastal mountains of British Columbia, Alaska, western Washington and western Oregon. It also occurs on mountain slopes on the outer coastal islands of British Columbia. It occurs at elevations ranging from 300 to 2300 m (1000-7500 feet). At the highest altitudes, the forest may begin to break up, forming "tree islands" that are surrounded by meadows or shrublands, where they form the "parkland" habitats before giving way to treeline. The lower and upper elevational limits decrease from south to north and from east to west. Tsuga mertensiana is one of the dominant tree species throughout, and Abies amabilis becomes an important associated species in the southern and central portion of the range, and drops out completely for the Alaska portion of this group''s range. Tsuga heterophylla often occurs at lower elevations in this group but is much less abundant than Tsuga mertensiana. Callitropsis nootkatensis occurs in the more coastal-influenced sections, decreasing with increasing continental climate, while Abies lasiocarpa is found inland and becomes increasingly common near the transition to the Subalpine Fir-Engelmann Spruce Zone in the Cascades and British Columbia. On the leeward side of the Cascades, the group is usually a dense canopy composed of Abies lasiocarpa and Tsuga mertensiana, with some Picea engelmannii or Abies amabilis. In Alaska Abies lasiocarpa mixes with the canopy of Tsuga mertensiana in some locations. Picea sitchensis and Thuja plicata are occasionally present. Deciduous trees are rare. Common understory species include Blechnum spicant, Elliottia pyroliflora, Empetrum nigrum, Geum calthifolium, Vaccinium ovalifolium, Gymnocarpium dryopteris, Harrimanella stelleriana, Luetkea pectinata, Menziesia ferruginea, Nephrophyllidium crista-galli, Phyllodoce aleutica (or Phyllodoce glanduliflora), Rubus pedatus, Streptopus lanceolatus, Tiarella trifoliata, Vaccinium membranaceum, and Vaccinium ovalifolium.

Diagnostic Characteristics: Dominance of Tsuga mertensiana singly or with Abies amabilis. Other conifers may be present. May form large continuous forests or small clumps of trees.

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: At its southern border, this group merges into ~Sierra-Cascade Red Fir - Mountain Hemlock Forest Group (G749 )$$ in the Cascade Range south of Crater Lake National Park in Oregon. The central Oregon Cascades, and the eastern slope of the Cascades in Washington all have important high-severity fire regime (occasional intense fires), warmer, drier summers, and little to no Abies amabilis, and may have other floristic differences from the forests west of coastal mountain divide from northern Oregon to southeastern Alaska which have very little to no fire, lots of Abies amabilis, and cool summers. This group includes what the Alaska Natural Heritage Program calls Maritime Subalpine Fir-Mountain Hemlock Forest. These differences may be best handled at the alliance level.

Placement of the following associations in this group needs review as they could be Rocky Mountain associations. Even though they are on the lee side of the Coast, they are likely more floristically related to interior types: ~Abies lasiocarpa / Valeriana sitchensis - Luzula glabrata var. hitchcockii Forest (CEGL000345)$$; ~Abies lasiocarpa / Vaccinium membranaceum / Valeriana sitchensis Forest (CEGL002612)$$; ~Abies lasiocarpa / Phyllodoce empetriformis Woodland (CEGL000920)$$; and ~Abies lasiocarpa - Pseudotsuga menziesii / Acer circinatum Woodland (CEGL000921)$$. And should the following association be placed in G244: ~Callitropsis nootkatensis Subalpine Parkland Woodland (CEGL000350)$$.

Similar NVC Types: No Data Available

note: No Data Available