Print Report

G218 Picea engelmannii - Abies lasiocarpa - Tsuga mertensiana Moist Forest & Woodland Group

Type Concept Sentence: This is a high-elevation forest group of mesic sites within the Rocky Mountains and eastern Cascades dominated by Picea engelmannii and Abies lasiocarpa where occurrences are typically found in locations with cold-air drainage or ponding, or where snowpacks linger late into the summer. Moisture-loving understory species are diagnostic of this group.


Common (Translated Scientific) Name: Engelmann Spruce - Subalpine Fir - Mountain Hemlock Moist Forest & Woodland Group

Colloquial Name: Rocky Mountain Subalpine Moist Spruce - Fir Forest & Woodland

Hierarchy Level:  Group

Type Concept: This is a high-elevation group of the Rocky Mountains and eastern Cascades dominated by Picea engelmannii and Abies lasiocarpa. It extends westward into the northeastern side of Mount Rainier in Washington, and as far east as mountain "islands" of north-central Montana. Picea engelmannii is generally more important in southern forests than those in the Pacific Northwest. Occurrences are typically found in locations with cold-air drainage or ponding, or where snowpacks linger late into the summer, such as north-facing slopes and high-elevation ravines. They can extend down in elevation below the subalpine zone in places where cold-air ponding occurs; northerly and easterly aspects predominate. These forests are found on gentle to very steep mountain slopes, high-elevation ridgetops and upper slopes, plateaulike surfaces, basins, alluvial terraces, well-drained benches, and inactive stream terraces. In the northern Rocky Mountains of northern Idaho and Montana, Tsuga mertensiana occurs as small to large patches within the matrix of this mesic spruce-fir group and only in the most maritime of environments (the coldest and wettest of the more Continental subalpine fir forests). In parts of the northern Cascades, the climate is more maritime than typical for this group, but due to the lower snowfall in these rainshadow areas, summer drought may be more significant than snowpack in limiting tree regeneration in burned areas. Picea engelmannii is rare in these areas. Populus tremuloides is a common codominant tree in many disturbed stands. Moisture-loving understory species are diagnostic of this group and may include shrubs Cornus canadensis, Ledum glandulosum (rare), Menziesia ferruginea, Phyllodoce empetriformis, Rhododendron albiflorum, Rubus parviflorus, Salix spp. and Vaccinium membranaceum. The understory may also be dominated by mesic herbaceous species such as Actaea rubra, Calamagrostis canadensis, Clintonia uniflora, Erigeron eximius, Gymnocarpium dryopteris, Luzula glabrata var. hitchcockii, Maianthemum stellatum, Rubus pedatus, Saxifraga bronchialis, Thalictrum spp., Tiarella spp., and Valeriana sitchensis. Disturbances include occasional blowdown, insect outbreaks (30-50 years), mixed-severity fire, and stand-replacing fire (every 150-500 years). The more summer-dry climatic areas also have occasional high-severity fires.

Diagnostic Characteristics: These subalpine forest and woodlands are characterized by diagnostic subalpine trees Picea engelmannii, Abies lasiocarpa, and sometimes with Tsuga mertensiana with mesic to wet understory shrub species such as Cornus canadensis, Ledum glandulosum, Menziesia ferruginea, Phyllodoce empetriformis, Rhododendron albiflorum, Rubus parviflorus, Salix spp., and Vaccinium membranaceum, or mesic to wet herbaceous species such as Actaea rubra, Calamagrostis canadensis, Clintonia uniflora, Erigeron eximius, Gymnocarpium dryopteris, Luzula glabrata var. hitchcockii, Maianthemum stellatum, Rubus pedatus, Saxifraga bronchialis, Thalictrum fendleri, Tiarella spp., and Valeriana sitchensis.

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: This group is similar to ~Rocky Mountain Subalpine Dry-Mesic Spruce - Fir Forest & Woodland Group (G219)$$ but is distinguished by its occurrence on mesic to wet microsites within the matrix of the drier (and warmer) subalpine spruce-fir or lodgepole pine forests. The microsites include north-facing slopes, swales or ravines, toeslopes, cold pockets, and other locations where available soil moisture is higher or lasts longer into the growing season. This group is NOT confined to the northern Rocky Mountains or Pacific Northwest (it is not geographically defined, rather by topographic settings in the subalpine). In the Canadian Rockies, this group transitions to a yet-to-be described Boreal mesic mixed-conifer group, where Abies lasiocarpa and Picea engelmannii occur with boreal taxa, such as Picea mariana or Picea glauca.

While the name of this group suggests a Rocky Mountain distribution, floristic affinities of Engelmann spruce-subalpine fir forests in the eastern Cascades of Washington and Oregon are such that the spruce-fir forests of those regions are included in this group. The subalpine fir and Engelmann spruce-dominated forests of the northeastern side of Mount Rainier are included here. They are more similar to subalpine fir forests on the eastern slopes of the Cascades than they are to mountain hemlock forests. Subalpine fir forests found on the Olympic Peninsula and west of the Cascade crest are typically mixed with Tsuga mertensiana, Abies amabilis, Callitropsis nootkatensis, and other species with "Vancouverian rainforest" affinities, and are not included in this group.

The following associations need further review to confirm their placement in this group: ~Abies lasiocarpa / Cornus canadensis Forest (CEGL000309)$$ (swamp type?); ~Abies lasiocarpa - Picea engelmannii / Ribes (montigenum, lacustre, inerme) Forest (CEGL000331)$$ (a hodge-podge of indicators); ~Populus tremuloides - Abies lasiocarpa / Symphoricarpos oreophilus / Bromus carinatus Forest (CEGL000530)$$ (G219?); ~Populus tremuloides - Abies lasiocarpa / Symphoricarpos oreophilus / Tall Forbs Forest (CEGL000531)$$ (G219?); and ~Populus tremuloides - Abies lasiocarpa / Symphoricarpos oreophilus / Thalictrum fendleri Forest (CEGL000532)$$ (G219?).

Similar NVC Types: No Data Available
note: No Data Available

Physiognomy and Structure: This group is composed of needle-leaved evergreen forests and woodlands dominated by tall (>30 m) trees. Canopy is generally closed to moderately open.

Floristics: This is a high-elevation group of the Rocky Mountains and dry eastern Cascades typically dominated by Picea engelmannii and Abies lasiocarpa. In the northern Rocky Mountains of northern Idaho and Montana, Tsuga mertensiana occurs as small to large patches within the matrix of this mesic spruce-fir group and only in the most maritime of environments (the coldest and wettest of the more Continental subalpine fir forests). Populus tremuloides is a common codominant tree in many disturbed stands. Moisture-loving wet understory species are diagnostic of this group and may include shrubs Cornus canadensis, Ledum glandulosum, Menziesia ferruginea, Phyllodoce empetriformis, Rhododendron albiflorum, Rubus parviflorus, Salix brachycarpa, Salix glauca, Spiraea betulifolia, Symphoricarpos albus, and Vaccinium membranaceum. The understory may also be dominated by herbaceous species such as Actaea rubra, Calamagrostis canadensis, Carex siccata, Clintonia uniflora, Erigeron eximius, Eucephalus engelmannii (= Aster engelmannii), Gymnocarpium dryopteris, Heracleum maximum, Luzula glabrata var. hitchcockii, Maianthemum stellatum, Osmorhiza berteroi, Osmorhiza occidentalis, Packera cardamine, Packera sanguisorboides, Pedicularis racemosa, Rubus pedatus, Rudbeckia occidentalis, Saxifraga bronchialis, Thalictrum fendleri, Tiarella spp., Valeriana occidentalis, Valeriana sitchensis, and Xerophyllum tenax.

Dynamics:  Disturbances include occasional blowdown, insect outbreaks (30-50 years), mixed-severity fire, and stand-replacing fire (every 150-500 years). The more summer-dry climatic areas also have occasional high-severity fires.

Environmental Description:  Occurrences are typically found at high elevations in locations with cold-air drainage or ponding, or where snowpacks linger late into the summer, such as north-facing slopes and high-elevation ravines. They can extend down in elevation below the subalpine zone in places where cold-air ponding occurs; northerly and easterly aspects predominate. These forests are found on gentle to very steep mountain slopes, high-elevation ridgetops and upper slopes, plateaulike surfaces, basins, alluvial terraces, well-drained benches, and inactive stream terraces. Climate: Sites within this group are cold year-round, and precipitation is predominantly in the form of snow, which may persist until late summer. Snowpacks are deep and late-lying, and summers are cool. Frost is possible almost all summer and may be common in restricted topographic basins and benches. Occurrences are typically found in locations with ponding, or where snowpacks linger late into the summer, such as north-facing slopes and high-elevation ravines. They can extend down in elevation below the subalpine zone in places where cold-air ponding occurs; northerly and easterly aspects predominate.

Geographic Range: This group is found at high elevations of the Rocky Mountains, extending west into the northeastern side of Mount Rainier in Washington, and as far east as mountain "islands" of north-central Montana.

Nations: CA,US

States/Provinces:  AB, AZ, BC, CA?, CO, ID, MT, NM, NV, OR, UT, WA, WY




Confidence Level: Moderate

Confidence Level Comments: No Data Available

Grank: GNR

Greasons: No Data Available


Concept Lineage: No Data Available

Predecessors: No Data Available

Obsolete Names: No Data Available

Obsolete Parents: No Data Available

Synonomy: < Engelmann Spruce - Subalpine Fir: 206 (Eyre 1980)
>< Mountain Hemlock: 205 (Eyre 1980) [Mountain hemlock in the northern Rockies of MT, ID and northeast WA is included in this group.]

Concept Author(s): F.H. Eyre (1980)

Author of Description: K.A. Schulz

Acknowledgements: D. Tart

Version Date: 10-08-13

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