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A3724 Tsuga mertensiana - Tsuga heterophylla - Callitropsis nootkatensis Forest & Woodland Alliance

Type Concept Sentence: This alliance covers forests dominated by Tsuga mertensiana with Callitropsis nootkatensis and/or Tsuga heterophylla. Other tree species present include Picea sitchensis and/or Pinus contorta. Stands have with heavy snowfall in the winter, and occur within the subalpine Wet Hypermaritime Mountain Hemlock Subzone (MHwh) along the outer coast of British Columbia (elevations of 500-1100 m) and at still snowy but lower elevations in southeastern Alaska.

Common (Translated Scientific) Name: Mountain Hemlock - Western Hemlock - Alaska-cedar Forest & Woodland Alliance

Colloquial Name: Mountain Hemlock - Western Hemlock - Alaska-cedar Forest & Woodland

Hierarchy Level:  Alliance

Type Concept: This alliance covers forests dominated by Tsuga mertensiana with Callitropsis nootkatensis and/or Tsuga heterophylla. Other tree species present include Picea sitchensis and/or Pinus contorta. Understory shrubs include Alnus viridis ssp. sinuata, Calamagrostis nutkaensis, Caltha leptosepala ssp. howellii, Coptis aspleniifolia, Gaultheria shallon, Harrimanella stelleriana, Maianthemum dilatatum, Menziesia ferruginea, Nephrophyllidium crista-galli, Vaccinium alaskaense, Vaccinium ovalifolium, Vaccinium parvifolium, and/or Veratrum viride. These are stands have with heavy snowfall in the winter, and occur within the subalpine Wet Hypermaritime Mountain Hemlock Subzone (MHwh) along the outer coast of British Columbia (elevations of 500-1100 m) and at still snowy but lower elevations in southeastern Alaska. All occur on steep mid to upper slopes and well-drained productive sites with organic to mineral soils.

Diagnostic Characteristics: Full-statured forests dominated by Tsuga mertensiana. Stands may be codominated by Tsuga heterophylla and/or Callitropsis nootkatensis.

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: This alliance includes low-elevation full-statured forests dominated by Tsuga mertensiana in southeastern Alaska and northern British Columbia. Del Meidinger (pers. comm. 2014): "There is a fair amount of floristic variation in this proposed alliance as it encompasses dry to moist associations. The richer and moister associations have a stronger floristic signal that differentiates them from the mesic and drier/poorer associations that could be recognized at an alliance level. This includes species such as Streptopus, Caltha, Fauria, and Gymnocarpium."

Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: No Data Available

Floristics: This alliance covers forests dominated by Tsuga mertensiana with Callitropsis nootkatensis (= Chamaecyparis nootkatensis) and/or Tsuga heterophylla. Other tree species present include Picea sitchensis and/or Pinus contorta. Understory shrubs include Alnus viridis ssp. sinuata, Calamagrostis nutkaensis, Caltha leptosepala ssp. howellii, Coptis aspleniifolia, Gaultheria shallon, Harrimanella stelleriana, Maianthemum dilatatum, Menziesia ferruginea, Nephrophyllidium crista-galli, Vaccinium alaskaense, Vaccinium ovalifolium, Vaccinium parvifolium, and/or Veratrum viride.

Dynamics:  No Data Available
Environmental Description:  These are stands have with heavy snowfall in the winter, and occur within the subalpine Wet Hypermaritime Mountain Hemlock Subzone (MHwh) along the outer coast of British Columbia (elevations of 500-1100 m) and at still snowy but lower elevations in southeastern Alaska. All occur on steep mid to upper slopes and well-drained productive sites with organic to mineral soils.
Geographic Range: This alliance is found in southeastern coastal Alaska and British Columbia coastal mountains on islands and the mainland.

Nations: CA,US

States/Provinces:  AK, BC


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.e Western Hemlock - Red Alder / Yellow Skunk-cabbage Swamp Forest Group G853 1.B.3.Ng.1.e
Alliance A3724 Mountain Hemlock - Western Hemlock - Alaska-cedar Forest & Woodland Alliance A3724 1.B.3.Ng.1.e
Association CEGL003217 Mountain Hemlock - Western Hemlock / Sitka Alder Forest CEGL003217 1.B.3.Ng.1.e
Association CEGL003219 Mountain Hemlock - Western Hemlock / Oval-leaf Blueberry - Rusty Menziesia Forest CEGL003219 1.B.3.Ng.1.e
Association CEGL003243 Mountain Hemlock / Sitka Alder Forest CEGL003243 1.B.3.Ng.1.e
Association CEGL003245 Mountain Hemlock / Oval-leaf Blueberry / Deer-cabbage Woodland CEGL003245 1.B.3.Ng.1.e
Association CEGL003246 Mountain Hemlock / Oval-leaf Blueberry - Alaska Bell-heather Woodland CEGL003246 1.B.3.Ng.1.e
Association CEGL003247 Mountain Hemlock / (Alaska Blueberry, Oval-leaf Blueberry) / Howell''s Marsh-marigold Forest CEGL003247 1.B.3.Ng.1.e
Association CEGL005584 Mountain Hemlock - Sitka Spruce / (Alaska Blueberry, Oval-leaf Blueberry) Forest CEGL005584 1.B.3.Ng.1.e
Association CEGL007338 Mountain Hemlock / (Alaska Blueberry, Oval-leaf Blueberry) / American Skunk-cabbage Swamp Forest CEGL007338 1.B.3.Ng.1.e
Association CEGL007376 Western Red-cedar - Alaska-cedar - Western Hemlock / Salal / American Skunk-cabbage Forest CEGL007376 1.B.3.Ng.1.e
Association CEGL007378 Mountain Hemlock - Western Hemlock / (Alaska Blueberry, Oval-leaf Blueberry) Forest CEGL007378 1.B.3.Ng.1.e
Concept Lineage: No Data Available

Predecessors: No Data Available

Obsolete Names: No Data Available

Obsolete Parents: No Data Available
Synonomy: No Data Available
Concept Author(s): G. Kittel, in Faber-Langendoen et al. (2013)

Author of Description: G. Kittel

Acknowledgements: No Data Available

Version Date: 12-18-14
  • 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.