Print Report

A3386 Abies amabilis - Tsuga heterophylla / Achlys triphylla Forest Alliance

Type Concept Sentence: This is an alliance of montane forests of the Pacific Northwest dominated by Abies amabilis, and mixed with Tsuga heterophylla and/or Pseudotsuga menziesii. They occur above lowland forests and below subalpine parklands. These forests have a characteristic elevation (approximately 800-1500 m in the Cascades and 0-1200 m in the Olympic Mountains).

Common (Translated Scientific) Name: Pacific Silver Fir - Western Hemlock / Sweet After Death Forest Alliance

Colloquial Name: Pacific Silver Fir - Western Hemlock / Sweet After Death Forest

Hierarchy Level:  Alliance

Type Concept: This is a typically mixed conifer forest alliance with Tsuga heterophylla codominant with Abies amabilis in the overstory; Pseudotsuga menziesii may be present in the canopy depending on site history. Abies amabilis is the most shade-tolerant conifer and is dominant in all age classes. Callitropsis nootkatensis may be frequent in the upper elevations of the alliance and is occasionally codominant. Associated shrubs are primarily ericaceous. Acer circinatum, Gaultheria shallon, Mahonia nervosa, Rhododendron macrophyllum, Rubus pedatus, or Vaccinium alaskaense dominate the shrub layer when present, and Blechnum spicant and Vaccinium alaskaense are strong indicators for direct maritime climate. The herbaceous layer is generally dominated by shade-tolerant species, often with strong maritime indicators, including Achlys californica, Achlys triphylla, Blechnum spicant, Cornus unalaschkensis, Maianthemum stellatum, Polystichum munitum, Streptopus lanceolatus var. curvipes, Tiarella trifoliata var. unifoliata, and many others. An upper tree canopy that is dominated or codominated by Abies amabilis is diagnostic of this forest alliance. The elevational range for this alliance is 800-1500 m in the Cascades, and sea level to 1200 m in the Olympic Mountains northward through British Columbia. Stands typically occupy moderate to steep middle and upper mountain slopes and are often contiguous with low-elevation Tsuga heterophylla and/or Pseudotsuga menziesii forests and higher subalpine forests of Tsuga mertensiana and Callitropsis nootkatensis.

Diagnostic Characteristics: These montane forests are dominated by Abies amabilis, and mixed with Tsuga heterophylla and/or Pseudotsuga menziesii. They occur above lowland forests and below subalpine parklands. These forests have a characteristic elevation (approximately 800-1500 m in the Cascades and 0-1200 m in the Olympic Mountains).

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: Achlys triphylla may not be a good indicator species in the name, as it occurs in less than 10% of the 1000 British Columbia plots of this alliance.

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.

Floristics: This is a mixed conifer forest alliance with Tsuga heterophylla codominant with Abies amabilis in the overstory; Pseudotsuga menziesii may be present in the canopy depending on site history. 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 of the alliance and is occasionally codominant. Associated shrubs are primarily ericaceous. Acer circinatum, Gaultheria shallon, Mahonia nervosa, Rhododendron macrophyllum, Rubus pedatus, or Vaccinium alaskaense dominate the shrub layer when present, and Blechnum spicant and Vaccinium alaskaense are strong indicators for direct maritime climate. The herbaceous layer is generally dominated by shade-tolerant species, often with strong maritime indicators, including Achlys californica, Achlys triphylla, Blechnum spicant, Cornus unalaschkensis, Maianthemum stellatum, Polystichum munitum, Streptopus lanceolatus var. curvipes, Tiarella trifoliata var. unifoliata, and many others.

Dynamics:  These forests have a high- and moderate-severity fire regime with natural return intervals of 100-600 years. Pseudotsuga menziesii colonizes vigorously and is favored with logging and/or fire disturbance to these forests. With increasing time since disturbance, Tsuga heterophylla or Thuja plicata become more abundant in the canopy, due to their ability to regenerate under closed-canopy conditions. Logging often results in conversion to deciduous or mixed forest with Alnus rubra or Acer macrophyllum. Much of the landscape in Oregon and Washington where this alliance is found is now composed of structurally simple Pseudotsuga menziesii plantations. In outer coastal areas, windthrow during intense winter storms is the most frequent form of stand replacement.
Environmental Description:  The elevational range for this alliance is 800-1500 m in the Cascades, and sea level to 1200 m in the Olympic Mountains northward through British Columbia. Stands typically occupy moderate to steep middle and upper mountain slopes and are often contiguous with low-elevation Tsuga heterophylla and/or Pseudotsuga menziesii forests and higher subalpine forests of Tsuga mertensiana and Callitropsis nootkatensis.
Geographic Range: This alliance is found in coastal mountains of British Columbia, Washington, Oregon and possibly 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 A3386 Pacific Silver Fir - Western Hemlock / Sweet After Death Forest Alliance A3386 1.B.2.Nd.3.d
Association CEGL000006 Pacific Silver Fir / Western Swordfern Forest CEGL000006 1.B.2.Nd.3.d
Association CEGL000217 Western Hemlock - Pacific Silver Fir - Douglas-fir / Cascade Barberry Forest CEGL000217 1.B.2.Nd.3.d
Association CEGL000218 Pacific Silver Fir / Pacific Rhododendron - Cascade Barberry Forest CEGL000218 1.B.2.Nd.3.d
Association CEGL005510 Pacific Silver Fir / Thinleaf Huckleberry / Oneleaf Foamflower - Sitka Valerian Forest CEGL005510 1.B.2.Nd.3.d
Association CEGL005511 Pacific Silver Fir - Douglas-fir / Sweet After Death Forest CEGL005511 1.B.2.Nd.3.d
Association CEGL005512 Pacific Silver Fir - (Douglas-fir) / Sweet After Death - Oneleaf Foamflower Forest CEGL005512 1.B.2.Nd.3.d
Association CEGL005514 Pacific Silver Fir - (Douglas-fir) / Thinleaf Huckleberry / Sweet After Death Forest CEGL005514 1.B.2.Nd.3.d
Association CEGL005515 Pacific Silver Fir - Western Hemlock / Strawberry-leaf Raspberry - Oneleaf Foamflower Forest CEGL005515 1.B.2.Nd.3.d
Association CEGL005549 Western Hemlock - (Pacific Silver Fir) / Salal / Deer Fern Forest CEGL005549 1.B.2.Nd.3.d
Association CEGL005564 Western Hemlock - Pacific Silver Fir / Redwood Sorrel - Deer Fern Forest CEGL005564 1.B.2.Nd.3.d
Association CEGL005566 Western Hemlock - Pacific Silver Fir / Alaska Blueberry / Oneleaf Foamflower Forest CEGL005566 1.B.2.Nd.3.d
Association CEGL005567 Western Hemlock - Pacific Silver Fir - Douglas-fir / Salal Forest CEGL005567 1.B.2.Nd.3.d
Association CEGL005569 Western Hemlock - Pacific Silver Fir - Douglas-fir / Redwood Sorrel Forest CEGL005569 1.B.2.Nd.3.d
Association CEGL005577 Western Hemlock - Western Red-cedar / Salal / Deer Fern Forest CEGL005577 1.B.2.Nd.3.d
Association CEGL007319 Western Hemlock - Pacific Silver Fir - (Western Red-cedar) / Alaska Blueberry / Deer Fern Forest CEGL007319 1.B.2.Nd.3.d
Concept Lineage: proto-alliance A.NCCN-007 (edited)

Predecessors: No Data Available

Obsolete Names: No Data Available

Obsolete Parents: No Data Available
Synonomy: >< Coastal True Fir - Hemlock: 226 (Eyre 1980)
>< Douglas fir-western hemlock, # 230 (Küchler 1964)
>< Douglas-fir - Western Hemlock: 230 (Eyre 1980)
>< Pacific silver fir series (Atzet and McCrimmon 1990)
>< Western Hemlock: 224 (Eyre 1980)
>< Western Needleleaf Forests: 2: Cedar-Hemlock-Douglas Fir Forest (Thuja-Tsuga-Pseudotsuga) (Küchler 1964)
>< Western Needleleaf Forests: 3: Silver Fir-Douglas Fir Forest (Abies-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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