Alnus viridis Provisional Shrubland Alliance
Sitka alder thickets

Summary Information

  • Primary Life FormShrub
  • Elevation0-3000 m
  • State RarityS3?
  • Global RarityG5
  • DistributionUSA: AK, CA, OR, WA (NatureServe)
  • Endemic to CaliforniaNo
  • Endemic to California Floristic Province and DesertsNo
  • Date Added1995/11/01

Characteristic Species

Alnus viridis is dominant or co-dominant in the shrub canopy with Acer glabrum, Alnus incana, Cornus sericea, Rubus spp., Salix jepsonii, Salix lemmonii, Salix scouleriana and Vaccinium spp. Emergent trees may be present at low cover, including Abies magnifica or Tsuga mertensiana.

Vegetation Layers

Shrubs < 5 m; canopy is continuous. Herbaceous layer is variable and usually well developed.


Montane to subalpine streamsides, seeps, ponds, and lake margins. The USFWS Wetland Inventory (1996 national list) recognizes Alnus viridis ssp. sinuata as an FACW plant.

Other Habitat, Alliance, and Community Groupings

MCV (1995) Montane wetland shrub habitat, Sitka alder series
NVCS (2009) Alnus viridis ssp sinuata seasonally flooded shrubland alliance, Alnus viridis temporarily flooded shrubland alliance
Calveg Riparian mixed shrub, Mountain alder
Holland Montane riparian scrub
Munz Red fir forest
WHR Montane riparian
CDFW CA Code 63.220.00