Print Report
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
Plot Analysis Summary:
http://vegbank.org/natureserve/ELEMENT_GLOBAL.2.899511
Confidence Level: Low
Confidence Level Comments: No Data Available
Grank: GNR
Greasons: No Data Available
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)
>< Mountain Hemlock: 205 (Eyre 1980)
>< Sierra Nevada Mixed Conifer: 243 (Eyre 1980)
>< Western Needleleaf Forests: 5: Mixed Conifer Forest (Abies-Pinus-Pseudotsuga) (Küchler 1964)
- Antos, J. A., and D. B. Zobel. 1986. Habitat relationships of Chamaecyparis nootkatensis in southern Washington, Oregon, and California. Canadian Journal of Botany 64:1898-1909.
- Atzet, T. A., D. E. White, L. A. McCrimmon, P. A. Martinez, P. R. Fong, and V. D. Randall. 1996. Field guide to the forested plant associations of southwestern Oregon. Technical Paper R6-NR-ECOL-TP-17-96. USDA Forest Service, Pacific Northwest Region, Portland, OR.
- Atzet, T., and L. A. McCrimmon. 1990. Preliminary plant associations of the southern Oregon Cascade Mountain Province. USDA Forest Service, Pacific Northwest Region, Siskiyou National Forest, Grants Pass, OR. 330 pp.
- Chappell, C., R. Crawford, J. Kagan, and P. J. Doran. 1997. A vegetation, land use, and habitat classification system for the terrestrial and aquatic ecosystems of Oregon and Washington. Unpublished report prepared for Wildlife habitat and species associations within Oregon and Washington landscapes: Building a common understanding for management. Prepared by Washington and Oregon Natural Heritage Programs, Olympia, WA, and Portland, OR. 177 pp.
- Eyre, F. H., editor. 1980. Forest cover types of the United States and Canada. Society of American Foresters, Washington, DC. 148 pp.
- Faber-Langendoen, D., J. Drake, M. Hall, G. Kittel, S. Menard, C. Nordman, M. Pyne, M. Reid, M. Russo, K. Schulz, L. Sneddon, K. Snow, and J. Teague. 2013-2019b. Screening alliances for induction into the U.S. National Vegetation Classification: Part 1 - Alliance concept review. NatureServe, Arlington, VA.
- Franklin, J. F., W. H. Moir, M. A. Hemstrom, S. E. Greene, and B. G. Smith. 1988. The forest communities of Mount Rainier National Park. USDI National Park Service. Scientific Monograph Series 19. Washington, DC. 194 pp.
- Franklin, J. F., W. H. Moir, M. A. Hemstrom, and S. Greene. 1979. Forest ecosystems of Mount Rainier National Park. Unpublished report prepared for the USDI National Park Service.
- Hemstrom, M. A., S. E. Logan, and W. Pavlat. 1987. Plant association and management guide, Willamette National Forest. Report R6-Ecol 257-B-86. USDA Forest Service, Pacific Northwest Region, Portland, OR. 312 pp.
- Küchler, A. W. 1964. Potential natural vegetation of the conterminous United States. American Geographic Society Special Publication 36. New York, NY. 116 pp.