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A3725 Tsuga mertensiana Montane Alaskan Forest Alliance
Type Concept Sentence: This is a forested alliance of open canopy "parklands" dominated by Tsuga mertensiana and ericaceous and alpine shrubs and forbs such as Cassiope mertensiana, Elliottia pyroliflora, and Phyllodoce aleutica. It occurs from near sea level into the subalpine in Alaska coastal areas, on slope benches or canyon bottoms.
Common (Translated Scientific) Name: Mountain Hemlock Montane Alaskan Forest Alliance
Colloquial Name: Montane Alaskan Mountain Hemlock Forest
Hierarchy Level: Alliance
Type Concept: This is a forested alliance of open canopy "parklands" dominated by Tsuga mertensiana and ericaceous and alpine shrubs and forbs such as Cassiope mertensiana, Elliottia pyroliflora, and Phyllodoce aleutica. This woodland alliance occurs in cold, snowy subalpine environments from southern Alaska. It occurs from near sea level into the subalpine in Alaska coastal areas, on slope benches or canyon bottoms, which are prone to cold-air drainage. The alliance occurs on a wide variety of soils, including organic muskeg margins. Best growth of Tsuga mertensiana is reported on loose, coarse-textured, well-drained soils.
Diagnostic Characteristics: Open, lower-statured woodlands dominated by Tsuga mertensiana near treeline with ericaceous shrub understory.
Rationale for Nominal Species or Physiognomic Features: No Data Available
Classification Comments: Based on a description of Tsuga mertensiana / Cassiope spp. association by Martin et al. (1995) from the Chatham Area, Tongass National Forest. It was assumed the other member associations would occur in similar physical settings.
Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: This alliance is characterized by a dense coniferous forest of Tsuga mertensiana, a medium-sized conifer which is 20-35 m in height. Large (1-2 m tall) shrubs can form a dense understory.
Floristics: Vegetation is generally characterized by an overstory of Tsuga mertensiana. Important canopy codominants include Abies amabilis in coastal ranges. Understory species are often ericaceous shrubs such as species of Vaccinium, Rhododendron, or Menziesia. To the interior, where precipitation is lighter, it grades into Abies lasiocarpa and Pinus albicaulis subalpine forests. At its lower margin, the alliance grades into forests dominated by Tsuga heterophylla, Abies amabilis, or Abies grandis. Stands of Tsuga mertensiana often occur in mixed stands with some of these adjacent forest types.
Dynamics: Tsuga mertensiana is a slow-growing, long-lived conifer, which can regenerate under its own canopy, but can be succeeded by other shade-tolerant conifers, such as Tsuga heterophylla or Callitropsis nootkatensis at the lower or northern edges of its range. Fire often allows the seral invasion of Pinus contorta into associations of this type.
Environmental Description: It occurs from near sea level and up into higher elevations in the coastal ranges of Alaska. In interior ranges, it is generally associated with areas of maritime influence and deep winter snowpacks. Parklands can occur near treeline where extremely deep snowpacks discourage tree growth in topographic depressions, and the forest interdigitates with herbaceous communities. Stands occur on slope benches or canyon bottoms, which are prone to cold air drainage. The alliance occurs on a wide variety of soils.
Geographic Range: This alliance is found in coastal ranges of southeastern Alaska.
Nations: US
States/Provinces: AK
Plot Analysis Summary:
http://vegbank.org/natureserve/ELEMENT_GLOBAL.2.899777
Confidence Level: Moderate
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.4 California Red Fir - Mountain Hemlock - Sierra Lodgepole Pine Forest Macrogroup | M025 | 1.B.2.Nd.4 |
| Group | 1.B.2.Nd.4.d Alaskan Mountain Hemlock Forest Group | G850 | 1.B.2.Nd.4.d |
| Alliance | A3725 Mountain Hemlock Montane Alaskan Forest Alliance | A3725 | 1.B.2.Nd.4.d |
| Association | CEGL003248 Mountain Hemlock / Copperbush / Deer-cabbage Woodland | CEGL003248 | 1.B.2.Nd.4.d |
| Association | CEGL003250 Mountain Hemlock / Aleutian Mountain-heath / Deer-cabbage Woodland | CEGL003250 | 1.B.2.Nd.4.d |
| Association | CEGL003251 Mountain Hemlock / Western Moss-heather Woodland | CEGL003251 | 1.B.2.Nd.4.d |
| Association | CEGL003252 Mountain Hemlock / Western Moss-heather / Deer-cabbage Woodland | CEGL003252 | 1.B.2.Nd.4.d |
Concept Lineage: No Data Available
Predecessors: No Data Available
Obsolete Names: No Data Available
Obsolete Parents: No Data Available
Synonomy: >< Mountain Hemlock: 205 (Eyre 1980)
- 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.
- 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.
- Martin, R. R., S. J. Trull, W. W. Brady, R. A. West, and J. M. Downs. 1995. Forest plant association management guide, Chatham Area, Tongass National Forest. R10-RP-57. USDA Forest Service, Alaska Region.