Alnus rubra Forest Alliance
Red alder forest

USDA Ecological Section Map

Summary Information

  • Primary Life FormTree
  • Elevation0-750 m
  • State RarityS4
  • Global RarityG5
  • DistributionCAN: BC. USA: AK, CA, ID, OR, WA (NatureServe)
  • Endemic to CaliforniaNo
  • Endemic to California Floristic Province and DesertsNo
  • Date Added1995/11/01

Characteristic Species

Alnus rubra is dominant or co-dominant in the tree canopy with Abies grandis, Garrya elliptica, Picea sitchensis, Populus trichocarpa, Pseudotsuga menziesii, Salix hookeriana, Salix lasiolepis, Salix sitchensis, Sequoia sempervirens, Tsuga heterophylla and Umbellularia californica.

Vegetation Layers

Trees < 40 m; canopy is continuous. Shrub layer is sparse to intermittent. Herbaceous layer is open to continuous, especially with ferns and forbs.

Membership Rules

  • Alnus rubra > 50% relative cover in tree layer (Keeler-Wolf et al. 2003a, Evens and Kentner 2006).


Stream and river backwaters, banks, bottoms, flood plains, mouths, terraces, and slopes of all aspects. The USFWS Wetland Inventory (1996 national list) recognizes Alnus rubra as a FACW plant.

Other Habitat, Alliance and Community Groupings

MCV (1995) Red alder series
NVCS (2009) Alnus rubra forest alliance, Alnus rubra seasonally flooded forest alliance, Alnus rubra temporarily flooded forest alliance
Calveg Red alder
Holland Red alder riparian forest, North Coast riparian scrub, Woodwardia thicket, Red alder forest
Munz North Coast coniferous forest
WHR Montane hardwood-conifer
CDFW CA Code 61.410.00

National Vegetation Classification Hierarchy

Formation Class Mesomorphic Tree Vegetation (Forest and Woodland)
Formation Subclass Temperate Forest
Formation Cool Temperate Forest
Division Western North America Cool Temperate Forest
Macro Group Californian-Vancouverian Montane and Foothill Forest
Group Upland Vancouverian mixed woodland and forest