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A3766 Tsuga mertensiana - Abies amabilis Swamp Woodland Alliance
Type Concept Sentence: This alliance consists of montane riparian areas dominated by mixed forests with several conifers such as Tsuga mertensiana and/or Abies amabilis. Vegetation within this alliance occurs in cold, snowy subalpine environments of high coastal mountains. It has been reported from Oregon, Washington and British Columbia, but probably also occurs northward. It occurs from 760-1500 m in elevation, primarily west of the Cascade crest where maritime climate influence is strong and deep winter snowpacks are typical.
Common (Translated Scientific) Name: Mountain Hemlock - Pacific Silver Fir Swamp Woodland Alliance
Colloquial Name: Mountain Hemlock - Pacific Silver Fir Swamp Woodland
Hierarchy Level: Alliance
Type Concept: This alliance consists of communities that are typically mixed forests with several conifers in the overstory often dominated by Tsuga mertensiana and/or Abies amabilis. Additional tree species include Callitropsis nootkatensis, Pseudotsuga menziesii, Thuja plicata and Tsuga heterophylla. The shrub layer is moderately dense and is dominated by Acer circinatum, Menziesia ferruginea, Oplopanax horridus, Ribes bracteosum, Rubus parviflorus, Rubus pedatus, Rubus spectabilis, Vaccinium deliciosum, Vaccinium membranaceum, and/or Vaccinium ovalifolium. The sparse herbaceous layer is dominated by shade-tolerant forbs and ferns, such as Athyrium filix-femina, Blechnum spicant, Clintonia uniflora, Gymnocarpium dryopteris, Streptopus lanceolatus var. curvipes, and Tiarella trifoliata var. unifoliata. Vegetation within this alliance occurs in cold, snowy subalpine environments of high coastal mountains. It has been reported from Oregon, Washington and British Columbia, but probably also occurs northward. It occurs from 760-1500 m in elevation, primarily west of the Cascade crest where maritime climate influence is strong and deep winter snowpacks are typical. In the Olympic Mountains, this alliance occurs from 300-1200 m in elevation, reaching lowest elevations on the moist windward slope. Precipitation ranges from 150-400 cm annually, falling largely as snow, and snowpacks usually linger into June or later. These forests typically occur in subalpine habitats near the ecotone with subalpine parklands. Sites are cold, poorly drained and saturated because of shallow subirrigation, seeps, springs or small streams. Stands are found on gentle to steep, lower slopes, toeslopes, in ravines on terraces along streams, in depressions, around edges of lakes and valley bottoms. Substrates are moderately deep soils derived from colluvium, alpine till, glacial outwash, with volcanic ash overlaying granite. These soils are acidic, coarse-textured with a substantial organic component because of high moisture and low temperatures.
Diagnostic Characteristics: Wet forests dominated in the upper canopy with Tsuga mertensiana and/or Abies amabilis.
Rationale for Nominal Species or Physiognomic Features: No Data Available
Classification Comments: These are wet forests either on seeps, toeslopes or edges of streams.
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 approach or sometimes 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 deciduous or evergreen tall shrubs is well-developed. A cold-deciduous low-shrub layer is usually present and characteristic. The herbaceous layer is well-developed and includes shade-tolerant forbs or ferns. Small mud-bottomed openings are not uncommon, and tree density is typically relatively low. Large woody debris is common.
Floristics: Communities within this alliance are typically mixed forests with several other conifers in the overstory. Abies amabilis is the prominent species in the canopy, but Callitropsis nootkatensis (= Chamaecyparis nootkatensis), Pseudotsuga menziesii, Thuja plicata and Tsuga heterophylla may all be present in the canopy, depending upon elevation, soil moisture, geographic location, and site history. Abies amabilis is the most shade-tolerant conifer, however, and is dominant in all age classes. Associated shrubs include Acer circinatum, Menziesia ferruginea, Oplopanax horridus, Ribes bracteosum, Rubus parviflorus, Rubus pedatus, Rubus spectabilis, Vaccinium deliciosum, Vaccinium membranaceum, and/or Vaccinium ovalifolium. The herbaceous layer is generally dominated by shade-tolerant forbs and ferns, including Athyrium filix-femina , Blechnum spicant, Boykinia occidentalis (= Boykinia elata), Caltha leptosepala ssp. howellii, Clintonia uniflora, Gymnocarpium dryopteris, Lysichiton americanus, Maianthemum dilatatum, Mitella spp., Senecio triangularis, Streptopus lanceolatus var. curvipes (= Streptopus roseus), Tiarella trifoliata, Tiarella trifoliata var. unifoliata, Tolmiea menziesii, and/or Veratrum viride.
Dynamics: Stands in this alliance are typically late-seral, mixed-age communities which can persist for very long periods under the present climate. Following fire or other disturbance, Pseudotsuga menziesii or Abies procera commonly become established and can persist in the canopy for centuries. Although these species are considered seral to Abies amabilis, their longevity allows them to persist as important species in forests of this alliance. Fire is infrequent in these forests, however, and rotation intervals for this type have been estimated at approximately 1000 years in central Washington (Henderson et al. 1989). Windthrow is the most common agent of disturbance, due to wet soils and shallow rooting of the trees, and creates gaps in the canopy for regeneration.
Environmental Description: These communities occur in moist habitats at approximately 300-1500 m in elevation. These forests are located in ravines, on terraces along streams, in depressions, around edges of lakes, and on subirrigated slopes, which can be steep. Most stands are hydrated with seasonal ponding or flooding from snowmelt and runoff. Some sites are saturated with groundwater year-round. Podzolization is the dominant soil formation process and organic soil layers are generally well-developed. Fires are infrequent in these forests, due to high fuel moisture and sheltered topographic position.
Geographic Range: This alliance is found in the Coastal Mountains of British Columbia, and Coast and Cascade ranges of Oregon and Washington.
Nations: CA,US
States/Provinces: BC, OR, WA
Plot Analysis Summary:
http://vegbank.org/natureserve/ELEMENT_GLOBAL.2.899818
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.3 Temperate Flooded & Swamp Forest Formation | F026 | 1.B.3 |
| Division | 1.B.3.Ng Vancouverian Flooded & Swamp Forest Division | D193 | 1.B.3.Ng |
| Macrogroup | 1.B.3.Ng.1 Vancouverian Flooded & Swamp Forest Macrogroup | M035 | 1.B.3.Ng.1 |
| Group | 1.B.3.Ng.1.b Mountain Hemlock - Fir species / Willow species Montane Riparian Woodland Group | G507 | 1.B.3.Ng.1.b |
| Alliance | A3766 Mountain Hemlock - Pacific Silver Fir Swamp Woodland Alliance | A3766 | 1.B.3.Ng.1.b |
| Association | CEGL000004 Pacific Silver Fir - Western Hemlock / Devil''s-club Swamp Forest | CEGL000004 | 1.B.3.Ng.1.b |
| Association | CEGL000507 Pacific Silver Fir - Mountain Hemlock / Devil''s-club Swamp Forest | CEGL000507 | 1.B.3.Ng.1.b |
Concept Lineage: A.187 and A.207 Summaries together with edits]
Predecessors: No Data Available
Obsolete Names: No Data Available
Obsolete Parents: No Data Available
Synonomy: >< Tsuga mertensiana-Abies amabilis Forest (Chappell et al. 1997)
>< Coastal True Fir - Hemlock: 226 (Eyre 1980)
>< Mountain Hemlock Series (Henderson et al. 1992)
>< Mountain Hemlock: 205 (Eyre 1980)
>< Coastal True Fir - Hemlock: 226 (Eyre 1980)
>< Mountain Hemlock Series (Henderson et al. 1992)
>< Mountain Hemlock: 205 (Eyre 1980)
- Brockway, D. G., C. Topik, M. A. Hemstrom, and W. H. Emmingham. 1983. Plant association and management guide for the Pacific silver fir zone, Gifford Pinchot National Forest. Technical Report R6-Ecol-130a-1983. USDA Forest Service, Pacific Northwest Region, Portland, OR. 122 pp.
- Burns, R. M., and B. H. Honkala, technical coordinators. 1990a. Silvics of North America: Volume 1. Conifers. Agriculture Handbook 654. USDA Forest Service, Washington, DC. 675 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. 1966. Vegetation and soils in the subalpine forests of the southern Washington Cascade Range. Ph.D. dissertation, Washington State University, Pullman. 132 pp.
- 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.
- Hemstrom, M. A., W. H. Emmingham, N. M. Halverson, S. E. Logan, and C. Topik. 1982. Plant association and management guide for the pacific silver fir zone, Mt. Hood and Willamette national forests. R6-Ecol 100-1982a. USDA Forest Service, Pacific Northwest Region, Portland, OR. 104 pp.
- Henderson, J. A., D. A. Peter, R. Lesher, and D. C. Shaw. 1989. Forested plant associations of the Olympic National Forest. R6-ECOL-TP-001-88. USDA Forest Service, Pacific Northwest Region, Portland, OR. 502 pp.
- Henderson, J. A., D. A. Peter, R. Lesher, and D. C. Shaw. 1992. Field guide to forested plant associations of the Mt. Baker-Snoqualmie National Forest. Technical Paper R6-ECOL-TP-028-91. USDA Forest Service, Pacific Northwest Region, Portland, OR. 196 pp.
- Henderson, J. A., D. A. Peter, and R. Lesher. 1985. Preliminary plant associations and habitat types of the Mt. Baker Ranger District, Mt. Baker-Snoqualmie National Forest. Unpublished report for USDA Forest Service, Pacific Northwest Region. 74 pp.
- Henderson, J. A., D. A. Peter, and R. Lesher. 1986. Preliminary plant associations of the Olympic National Forest. USDA Forest Service, Pacific Northwest Region. 136 pp.
- Henderson, J. A., and D. Peter. 1981. Preliminary plant associations and habitat types of the Green and Cedar River drainages. North Bend District, Mt. Baker-Snoqualmie National Forest. Unpublished report prepared for USDA Forest Service. 48 pp.
- Henderson, J. A., and D. Peter. 1982. Preliminary plant associations and habitat types of the Snoqualmie and adjacent Skykomish River drainages, Mt. Baker-Snoqualmie National Forest. Unpublished report prepared for USDA Forest Service, Pacific Northwest Region. 87 pp.
- Henderson, J. A., and D. Peter. 1983. Preliminary plant associations and habitat types of the Skykomish Ranger District, Mt. Baker-Snoqualmie National Forest. Unpublished report prepared for USDA Forest Service, Pacific Northwest Region. 67 pp.
- Henderson, J. A., and D. Peter. 1984. Preliminary plant associations and habitat types of the Darrington Ranger District, Mt. Baker-Snoqualmie National Forest. USDA Forest Service, Pacific Northwest Region. 69 pp.
- Lillybridge, T. R., B. L. Kovalchik, C. K. Williams, and B. G. Smith. 1995. Field guide for forested plant associations of the Wenatchee National Forest. General Technical Report PNW-GTR-359. USDA Forest Service, Pacific Northwest Research Station, Portland, OR. 335 pp.
- Williams, C. K., and B. G. Smith. 1990. Forested plant associations of the Wenatchee National Forest. Unpublished draft prepared by the USDA Forest Service, Pacific Northwest Region, Portland, OR. 217 pp.