Populus fremontii - Fraxinus velutina - Salix gooddingii Forest & Woodland Alliance
Fremont cottonwood forest and woodland

USDA Ecological Section Map

Summary Information

  • Primary Life FormTree
  • Elevation0-2400 m
  • State RarityS3.2
  • Global RarityG4
  • DistributionUSA: AZ, CA, CO, NM, NV, TX, UT, WY. Mexico (NatureServe)
  • Endemic to CaliforniaNo
  • Endemic to California Floristic Province and DesertsNo
  • Date Added1995/11/01

Characteristic Species

Populus fremontii is dominant or co-dominant in the tree canopy with Acer negundo, Baccharis sergiloides, Fraxinus latifolia, Fraxinus velutina, Juglans hindsii, Juglans hindsii × regia, Platanus racemosa, Quercus agrifolia, Salix exigua, Salix gooddingii, Salix laevigata, Salix lasiolepis, Salix lucida ssp. lasiandra and Salix lutea.

Vegetation Layers

Trees < 25 m; canopy is continuous to open. Shrub layer is intermittent to open. Herbaceous layer is variable.

Membership Rules

  • Populus fremonitii > 5% absolute cover in the tree layer (Potter 2005).
  • Populus fremontii > 50% relative cover in the tree layer (Keeler-Wolf et al. 1998b, Thomas et al. 2004).
  • Populus fremontii > 50% relative cover in the tree layer, though sometimes P. fremontii > 30% relative cover if Salix species are co-dominant (Evens and San 2005, Klein and Evens 2005, cf. Stillwater Sciences and URS 2007).


On floodplains, along low-gradient rivers, perennial or seasonally intermittent streams, springs, in lower canyons in desert mountains, in alluvial fans, and in valleys with a dependable subsurface water supply that varies considerably during the year. The USFWS Wetland Inventory (1996 national list) recognizes Populus fremontii as a FACW plant.

Other Habitat, Alliance and Community Groupings

MCV (1995) Fremont cottonwood series
NVCS (2009) Populus fremontii seasonally flooded woodland alliance, Populus fremontii temporarily flooded forest alliance, Populus fremontii temporarily flooded woodland alliance
Calveg Fremont cottonwood
Holland Central Coast cottonwood-sycamore riparian forest, Southern cottonwood-willow riparian forest, Great Valley cottonwood riparian forest, Great Valley mixed riparian forest, Modoc-Great Basin cottonwood-willow riparian forest, Mojave riparian forest, Sonoran cottonwood-willow riparian forest
Munz Not treated
WHR Desert riparian, Montane riparian, Valley foothill riparian
CDFW CA Code 61.130.00

National Vegetation Classification Hierarchy

Formation Class Mesomorphic Tree Vegetation (Forest and Woodland)
Formation Subclass Temperate Forest
Formation Temperate Flooded and Swamp Forest
Division Western North America Warm Temperate Flooded and Swamp Forest
Macro Group Southwestern North American Riparian, Flooded and Swamp Forest
Group Southwestern North American riparian evergreen and deciduous woodland