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A3387 Abies amabilis - Tsuga heterophylla / Vaccinium membranaceum Cold Forest Alliance

Type Concept Sentence: These are tall evergreen forests dominated by a mix of Abies amabilis and Tsuga heterophylla often with Pseudotsuga menziesii, but the latter may be absent. These forests occupy a broad elevational band in the Cascades, extending from approximately 1000-1500 m elevation. In the Olympic Mountains and northward through British Columbia, elevations range from approximately 1000-1200 m.


Common (Translated Scientific) Name: Pacific Silver Fir - Western Hemlock / Thinleaf Huckleberry Cold Forest Alliance

Colloquial Name: Pacific Silver Fir - Western Hemlock / Thinleaf Huckleberry Cold Forest

Hierarchy Level:  Alliance

Type Concept: These are tall evergreen forests dominated by a mix of Abies amabilis and Tsuga heterophylla often with Pseudotsuga menziesii, but the latter may be absent. In this typically mixed conifer forest, Tsuga heterophylla is usually codominant with Abies amabilis in the overstory; however, Tsuga mertensiana may also be present in the canopy. Abies amabilis is the most shade-tolerant conifer and is dominant in all age classes. Callitropsis nootkatensis may be frequent in the upper elevations and is occasionally codominant. Thuja plicata is also an occasional codominant. Associated shrubs are primarily ericaceous. Vaccinium membranaceum, Vaccinium ovalifolium, and Rhododendron albiflorum are common along with Menziesia ferruginea. The herbaceous layer is generally dominated by shade-tolerant species with northern affinities (i.e., cold-tolerant), including Clintonia uniflora, Cornus canadensis, Linnaea borealis, Orthilia secunda, Rubus lasiococcus, Valeriana sitchensis, Xerophyllum tenax, and many others. These forests occupy a broad elevational band in the Cascades, extending from approximately 1000 to 1500 m. In the Olympic Mountains and northward through British Columbia, elevations range from approximately 1000 to 1200 m. The climate is cool and wet with annual precipitation totals generally exceeding 200 cm and deep (1-3 m) snow accumulations. A consistent winter snowpack of moderate duration along with less frequent winter rain-on-snow events and more frequent snow-on-snow events are driving factors in the occurrence of these forests. Stands typically occupy moderate to steep middle and upper mountain slopes and are often contiguous with the lower-elevation forests.

Diagnostic Characteristics: These forests are matrix-forming, occurring in stands >100 acres in size. They are montane forests dominated by Abies amabilis, but mixed with Tsuga heterophylla and/or Pseudotsuga menziesii. They occur above lowland forests and the "warm" silver fir alliance and below parklands. Modeled by elevation (approximately 1000-1500 m), these forests occur well within the winter snow belt where precipitation is likely to be snow on snow. The presence of silver fir at these elevations is indicative of this alliance.

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: We may want to use Vaccinium alaskaense for the third trinomial.

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

Physiognomy and Structure: Forests within this alliance are characterized by a tall canopy of evergreen needle-leaved trees which can approach or exceed 50 m in height, ranging from 60-100% cover. Understory trees are usually shade-tolerant needle-leaved evergreens. Occasionally, a layer of broad-leaved evergreen shrubs is well-developed, particularly in wet, northern stands. The understory is typically shade-tolerant forbs or ferns, and foliar cover ranges widely in response to site moisture.

Floristics: These are tall evergreen forests dominated by a mix of Abies amabilis and Tsuga heterophylla often with Pseudotsuga menziesii, but the latter may be absent. In this typically mixed conifer forest, Tsuga heterophylla is usually codominant with Abies amabilis in the overstory; however, Tsuga mertensiana may also be present in the canopy. Abies amabilis is the most shade-tolerant conifer and is dominant in all age classes. Callitropsis nootkatensis (= Chamaecyparis nootkatensis) may be frequent in the upper elevations and is occasionally codominant. Thuja plicata is also an occasional codominant. Associated shrubs are primarily ericaceous. Vaccinium membranaceum, Vaccinium ovalifolium, and Rhododendron albiflorum are common along with Menziesia ferruginea. The herbaceous layer is generally dominated by shade-tolerant species with northern affinities (i.e., cold-tolerant), including Clintonia uniflora, Cornus canadensis, Linnaea borealis, Orthilia secunda, Rubus lasiococcus, Valeriana sitchensis, Xerophyllum tenax, and many others.

Dynamics:  These forests rarely burn and are often very old. Even-aged stands are believed to originate from stand-replacing disturbance (Franklin et al. 1988). Mixed stands result following fire or other disturbance, and Pseudotsuga menziesii or Abies amabilis becomes established and can persist in the canopy for centuries.

Environmental Description:  These forests occupy a broad elevational band in the Cascades, extending from approximately 1000 to 1500 m. In the Olympic Mountains and northward through British Columbia, elevations range from approximately 1000 to 1200 m. The climate is cool and wet with annual precipitation totals generally exceeding 200 cm and deep (1-3 m) snow accumulations. A consistent winter snowpack of moderate duration along with less frequent winter rain-on-snow events and more frequent snow-on-snow events are driving factors in the occurrence of these forests. Stands typically occupy moderate to steep middle and upper mountain slopes and are often contiguous with the lower-elevation forests.

Geographic Range: This alliance occurs in coastal mountains of British Columbia, Washington, Oregon, and possibly southeastern Alaska.

Nations: CA,US

States/Provinces:  AK, BC, CA?, OR, WA




Confidence Level: Low

Confidence Level Comments: No Data Available

Grank: GNR

Greasons: No Data Available

Type Name Database Code Classification Code
Class 1 Forest & Woodland Class C01 1
Subclass 1.B Temperate & Boreal Forest & Woodland Subclass S15 1.B
Formation 1.B.2 Cool Temperate Forest & Woodland Formation F008 1.B.2
Division 1.B.2.Nd Vancouverian Forest & Woodland Division D192 1.B.2.Nd
Macrogroup 1.B.2.Nd.3 Western Hemlock - Sitka Spruce - Redwood Rainforest Macrogroup M024 1.B.2.Nd.3
Group 1.B.2.Nd.3.d Pacific Silver Fir - Western Hemlock Rainforest Group G241 1.B.2.Nd.3.d
Alliance A3387 Pacific Silver Fir - Western Hemlock / Thinleaf Huckleberry Cold Forest Alliance A3387 1.B.2.Nd.3.d
Association CEGL000215 Pacific Silver Fir - Sierra White Fir / Cascade Barberry Forest CEGL000215 1.B.2.Nd.3.d
Association CEGL000216 Pacific Silver Fir - Sierra White Fir / Starry False Lily-of-the-Valley Forest CEGL000216 1.B.2.Nd.3.d
Association CEGL000222 Pacific Silver Fir / Pacific Rhododendron - Salal Forest CEGL000222 1.B.2.Nd.3.d
Association CEGL000224 Pacific Silver Fir / Rusty Menziesia Forest CEGL000224 1.B.2.Nd.3.d
Association CEGL000237 Pacific Silver Fir / Thinleaf Huckleberry - Threeleaf Foamflower Forest CEGL000237 1.B.2.Nd.3.d
Association CEGL000238 Pacific Silver Fir / Grouse Whortleberry Forest CEGL000238 1.B.2.Nd.3.d
Association CEGL000239 Pacific Silver Fir - (Douglas-fir, Noble Fir) / Thinleaf Huckleberry / Common Beargrass Forest CEGL000239 1.B.2.Nd.3.d
Association CEGL000351 Alaska-cedar / Oval-leaf Blueberry Forest CEGL000351 1.B.2.Nd.3.d
Association CEGL002833 Western Hemlock - Pacific Silver Fir - (Douglas-fir) / Splendid Feathermoss Forest CEGL002833 1.B.2.Nd.3.d
Association CEGL002850 Western Hemlock - Pacific Silver Fir - (Alaska-cedar) / Alaska Blueberry Forest CEGL002850 1.B.2.Nd.3.d
Association CEGL003444 Noble Fir / Redwood Sorrel Forest CEGL003444 1.B.2.Nd.3.d
Association CEGL005513 Pacific Silver Fir - Douglas-fir / Pacific Rhododendron / Western Cordilleran Bunchberry Forest CEGL005513 1.B.2.Nd.3.d
Association CEGL005516 Pacific Silver Fir - (Western Hemlock) / Thinleaf Huckleberry / Sidebells Wintergreen Forest CEGL005516 1.B.2.Nd.3.d
Association CEGL005517 Pacific Silver Fir - (Western Hemlock) / Thinleaf Huckleberry - Alaska Blueberry Forest CEGL005517 1.B.2.Nd.3.d
Association CEGL005518 Western Hemlock - Pacific Silver Fir - (Douglas-fir) / Alaska Blueberry Forest CEGL005518 1.B.2.Nd.3.d
Association CEGL005548 Pacific Silver Fir - (Douglas-fir, Western Hemlock) / Pacific Rhododendron Forest CEGL005548 1.B.2.Nd.3.d
Association CEGL005565 Western Hemlock - Pacific Silver Fir / Alaska Blueberry / Strawberry-leaf Raspberry Forest CEGL005565 1.B.2.Nd.3.d
Association CEGL005585 Western Hemlock - Pacific Silver Fir / Alaska Blueberry Forest CEGL005585 1.B.2.Nd.3.d

Concept Lineage: proto-alliance A.NCCN-008 (edited)

Predecessors: No Data Available

Obsolete Names: No Data Available

Obsolete Parents: No Data Available

Synonomy: >< Coastal True Fir - Hemlock: 226 (Eyre 1980)
>< Mountain Hemlock: 205 (Eyre 1980)
>< Sierra Nevada Mixed Conifer: 243 (Eyre 1980)
>< Western Needleleaf Forests: 5: Mixed Conifer Forest (Abies-Pinus-Pseudotsuga) (Küchler 1964)

Concept Author(s): G. Kittel, in Faber-Langendoen et al. (2013)

Author of Description: G. Kittel

Acknowledgements: No Data Available

Version Date: 09-26-14

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