Print Report

A3833 Alnus viridis ssp. sinuata - Alnus viridis ssp. fruticosa - Acer circinatum Shrub Swamp Alliance

Type Concept Sentence: These communities are located in the moderate- to high-elevation (1200-3000 m) riparian habitats of the Cascade and Coast ranges from British Columbia to northern California. They usually occur in somewhat steep drainages, which flood from spring snowmelt and winter rainstorms. A dense tall-shrub cover of Alnus viridis ssp. sinuata or Alnus viridis ssp. fruticosa or Acer circinatum characterizes this alliance.

Common (Translated Scientific) Name: Sitka Alder - Siberian Alder - Vine Maple Shrub Swamp Alliance

Colloquial Name: Pacific Green Alder - Vine Maple Shrub Swamp

Hierarchy Level:  Alliance

Type Concept: A dense tall-shrub cover of Alnus viridis ssp. sinuata or Alnus viridis ssp. fruticosa or Acer circinatum characterizes this alliance. Acer glabrum, Ribes lacustre, and Sorbus scopulina may also be present. Low cold-deciduous or ericaceous shrubs may be abundant, including Rubus spectabilis, Rubus parviflorus, Sambucus racemosa, and Vaccinium spp. A lush herbaceous layer is usually present, including forbs such as Aconitum columbianum, Achillea millefolium, Heracleum maximum, Osmorhiza berteroi, Senecio triangularis, Urtica dioica, and Veratrum viride, large ferns, including Athyrium filix-femina and Polystichum munitum. These communities are located in the moderate- to high-elevation (1200-3000 m) riparian habitats of the Cascade and Coast ranges from British Columbia to northern California. They usually occur in somewhat steep drainages, which flood from spring snowmelt and winter rainstorms. The wet soils and frequent fluvial disturbance act to discourage colonization by coniferous trees and allow full sunlight to reach the ground at these sites. Soils are often composed of sorted gravels and sands on aggraded fluvial terraces.

Diagnostic Characteristics: Tall riparian shrubland dominated by Alnus viridis or Acer circinatum.

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: Not well-documented but known to occur throughout steep drainages of the Pacific Northwest.

Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: This alliance has dense thickets of cold-deciduous shrubs approaching 4 m in height. Due to snow creep, the stems of the tall shrubs are usually convex in the downslope direction.

Floristics: These communities are characterized by a dense tall-shrub cover of Alnus viridis ssp. sinuata or Alnus viridis ssp. fruticosa. Acer circinatum and/or Alnus incana may be codominant in the tall-shrub layer in some stands. Acer glabrum, Spiraea douglasii, and Sorbus scopulina may also be present. Low cold-deciduous or ericaceous shrubs may be abundant, including Oplopanax horridus, Paxistima myrsinites, Rubus parviflorus, Rubus spectabilis, Sambucus racemosa, and Vaccinium spp., particularly west of the Cascade crest. A lush herbaceous layer is usually present, including forbs such as Aconitum columbianum, Achillea millefolium, Heracleum maximum (= Heracleum lanatum), Osmorhiza berteroi (= Osmorhiza chilensis), Senecio triangularis, Urtica dioica, and Veratrum viride, and large ferns, including Athyrium filix-femina and Polystichum munitum.

Dynamics:  This alliance usually occurs in sites that are wet and frequently disturbed by rock and snow movement. Alnus viridis ssp. sinuata is highly shade-intolerant and persists largely in forest openings with abundant light. It colonizes quickly, has rapid growth, and resprouts following fire, making it an important species on wet, disturbed sites.
Environmental Description:  This alliance occurs at moderate- to high-elevation (1200-3000 m) seep habitats of the Cascade Range where deep snow accumulations are common. Stands usually occur in shallow but deeply sloping ravines which receive moisture from snowmelt or groundwater discharge throughout the growing season. Often the ravines where these communities occur are also avalanche tracts. The wet soils and/or avalanche disturbance act to discourage colonization by coniferous trees and allow full sunlight to reach the ground at these sites. Soils are often composed of sorted gravels and sands on aggraded fluvial terraces, or unstable talus.
Geographic Range: This alliance is found in steep drainages of the Pacific Northwest.

Nations: CA,US

States/Provinces:  AK, BC, CA, ID?, MT, OR, WA


Confidence Level: Low

Confidence Level Comments: No Data Available
Grank: GNR

Greasons: No Data Available
Type Name Database Code Classification Code
Class 2 Shrub & Herb Vegetation Class C02 2
Subclass 2.C Shrub & Herb Wetland Subclass S44 2.C
Formation 2.C.4 Temperate to Polar Freshwater Marsh, Wet Meadow & Shrubland Formation F013 2.C.4
Division 2.C.4.Nb Western North American Temperate Freshwater Marsh, Wet Meadow & Shrubland Division D031 2.C.4.Nb
Macrogroup 2.C.4.Nb.4 Vancouverian Lowland Marsh, Wet Meadow & Shrubland Macrogroup M073 2.C.4.Nb.4
Group 2.C.4.Nb.4.c Alder species - Willow species - Meadowsweet species Wet Shrubland Group G322 2.C.4.Nb.4.c
Alliance A3833 Sitka Alder - Siberian Alder - Vine Maple Shrub Swamp Alliance A3833 2.C.4.Nb.4.c
Association CEGL001154 Sitka Alder Shrub Swamp CEGL001154 2.C.4.Nb.4.c
Association CEGL001155 Sitka Alder / Vine Maple Shrub Swamp CEGL001155 2.C.4.Nb.4.c
Association CEGL001157 Sitka Alder / Devil''s-club Shrub Swamp CEGL001157 2.C.4.Nb.4.c
Association CEGL003291 Vine Maple / Common Ladyfern - Piggyback Plant Shrub Swamp CEGL003291 2.C.4.Nb.4.c
Concept Lineage: No Data Available

Predecessors: No Data Available

Obsolete Names: No Data Available

Obsolete Parents: No Data Available
Synonomy: ? Alnus viridis (Sitka alder thickets) Provisional Alliance (Sawyer et al. 2009) [63.220.00]
Concept Author(s): G. Kittel, in Faber-Langendoen et al. (2013)

Author of Description: G. Kittel

Acknowledgements: No Data Available

Version Date: 01-08-14
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