Invalid Unit Specified
A0485 Washingtonia filifera Wet Woodland Alliance

The U.S. National
Vegetation Classification
Type Concept Sentence: This woodland alliance of the desert Southwest is found along canyon waterways and faultlines on intermittently flooded sites below 900 m in elevation. Permanent subsurface water is required to maintain Washingtonia filifera, a relict species. Only 24 sites are known to support oases in the Colorado and Sonoran deserts, one of the most arid regions in North America.
Collapse All::Expand All
Common (Translated Scientific) Name: California Fan Palm Wet Woodland Alliance
Colloquial Name: California Fan Palm Oasis
Hierarchy Level: Alliance
Type Concept: This alliance of the oases of the Colorado and Sonoran deserts is recognized by the presence of Washingtonia filifera as the sole or dominant tree in the canopy. There is great floristic diversity among oases, and this palm is the only species that does not differ in its relative importance. The vegetation of oases along waterways differs consistently from those along faultlines. Other trees that may be present include Fraxinus velutina, Platanus racemosa, Populus fremontii, and Quercus chrysolepis. A subcanopy is often present and may be composed of Prosopis glandulosa, Salix exigua, Salix gooddingii, and Salix lasiolepis. This woodland alliance of the desert Southwest is found along canyon waterways and faultlines on intermittently flooded sites below 900 m in elevation. Permanent subsurface water is required to maintain Washingtonia filifera, a relict species. Only 24 sites are known to support oases in the Colorado and Sonoran deserts, one of the most arid regions in North America. The mean 24-hour maximum temperature may exceed 38°C for several weeks a year. Annual precipitation totals between 90 and 168 mm. Salinity is low in the root zone, but increases near the surface where evaporation leaves salt accumulations. Reproduction of Washingtonia filifera is limited by water supply, surface salinity, rainfall, and fire. Oases are the only desert community in which fire is an important abiotic factor. Fan palms are fire-tolerant, while the understory species are not. Fires open up the understory allowing palm seedlings to establish. Removal of the understory also decreases competition for water.
Diagnostic Characteristics: Washingtonia filifera >3% absolute cover in the tree canopy (Keeler-Wolf et al. 1998a).
Rationale for Nominal Species or Physiognomic Features:
Classification Comments: There is great floristic variation among oases; however, canyon waterway oases differ consistently from those along faultlines in the importance of plants other than fan palms.
Similar NVC Types:
Physiognomy and Structure: This seasonally flooded, temperate, broad-leaved evergreen palm woodland of desert streams and seeps has an open to continuous canopy of emergent trees less than 30 m in height. Occasional, medium to tall shrubs may be present. The herbaceous layer is sparse.
Floristics: This alliance of the oases of the Colorado and Sonoran deserts is recognized by the presence of Washingtonia filifera as the sole or dominant tree in the canopy. There is great floristic diversity among oases, and this palm is the only species that doesn't differ in its relative importance. Oases along waterways differ consistently from those along faultlines. Other trees that may be present include Fraxinus velutina, Platanus racemosa, Populus fremontii, and Quercus chrysolepis. A subcanopy is often present and may be composed of Prosopis glandulosa, Salix exigua, Salix gooddingii, and Salix lasiolepis.
Dynamics: Seasonal flooding and fire are the dynamic processes required to maintain this alliance. Seasonal flooding reduces salinity in the surface soils and moistens the substrate for germination of Washingtonia filifera. This species also requires full sun to germinate and thrive. The oases where these trees grow form one of the few desert communities which can carry fire. Washingtonia is fire-resistant, while the other species in this community are not. Periodic fires clear the understory and reduce competition for water. The most favorable conditions for reproduction of Washingtonia occur when a late-season fire opens the understory before a moist winter. Once established, the palms require permanent soil moisture.
Environmental Description: This woodland alliance of the desert Southwest is found along canyon waterways and faultlines on intermittently flooded sites below 900 m in elevation. Permanent subsurface water is required to maintain Washingtonia filifera, a relict species. Only 24 sites are known to support oases in the Colorado and Sonoran deserts, one of the most arid regions in North America. The mean 24-hour maximum temperature may exceed 38°C for several weeks a year. Annual precipitation totals between 90 and 168 mm. Salinity is low in the root zone, but increases near the surface where evaporation leaves salt accumulations. Reproduction of Washingtonia filifera is limited by water supply, surface salinity, rainfall, and fire. Oases are the only desert community in which fire is an important abiotic factor. Fan palms are fire-tolerant, while the understory species are not. Fires open up the understory allowing palm seedlings to establish. Removal of the understory also decreases competition for water.
Geographic Range: This woodland alliance occurs on faultlines and canyon waterways which flood seasonally in the arid deserts of the American Southwest and western Mexico. There are currently 24 known examples of this alliance in Arizona, Nevada, and California.
Nations: MX, US
States/Provinces: AZ, CA, NV
US Forest Service Ecoregions (1994/1995)
Domain Name:
Division Name:
Province Name:
Province Code:     Occurrence Status:
Section Name:
Section Code:     Occurrence Status:
Omernik Ecoregions:
Confidence Level: Low
Confidence Level Comments:
Grank: GNR
Greasons: With fire suppression occurring over the past 60 or more years in the Colorado Desert, stands have developed dense, tall understories of shrubs and young palms, posing severe fire hazards to the stands (Howard 1992b). Agricultural and urban development have disturbed many oases; lowering or raising water tables have eliminated others. Near the San Andreas Fault, palms that receive percolating water through rock fractures sometimes perish when the fault shifts. Proper management involves an active fire plan. Palm oases are popular destinations for hikers and ORV enthusiasts. Vegetation disturbance and vandalism are of continuing management concerns.
Name:Database Code:Classification Code:
Class 1 Forest & Woodland C01 1
Subclass 1.B Temperate & Boreal Forest & Woodland S15 1.B
Formation 1.B.3 Temperate Flooded & Swamp Forest F026 1.B.3
Division 1.B.3.Nd Western North American Interior Flooded Forest D013 1.B.3.Nd
Macrogroup M036 Interior Warm & Cool Desert Riparian Forest M036 1.B.3.Nd.2
Group G797 Western Interior Riparian Forest & Woodland G797 1.B.3.Nd.2.b
Alliance A0485 California Fan Palm Oasis A0485
Association CEGL000001 CEGL000001
Concept Lineage:
Predecessors:
Obsolete Names:
Washingtonia filifera Flooded Woodland Alliance
Obsolete Parents:
Synonomy: = Washingtonia filifera (California fan palm oasis) Alliance (Sawyer et al. 2009) [61.520.00]
= Washingtonia filifera Woodland Alliance (Evens et al. 2012)
= Washingtonia filifera Woodland Alliance (CNPS 2017) [61.520.00]
= Desert Fan Palm Oasis Woodland (#62300) (Holland 1986b)
= Fan palm series (Sawyer and Keeler-Wolf 1995)
Concept Author(s): M. Schindel, in Faber-Langendoen et al. (2013)
Author of Description: G. Kittel
Acknowledgements:
Version Date: 18Dec2014
References:
  • Anderson, M. K., and W. Roderick. 2005. Fan palm Washingtonia filifera (L. Linden) H. Wendl. In: Plant guide [online]. USDA NRCS, National Plant Data Center, Baton Rouge, LA and Boise, ID.
  • Barbour, M. G., and J. Major, editors. 1977. Terrestrial vegetation of California. John Wiley and Sons, New York. 1002 pp.
  • Burk, J. H. 1977. Sonoran Desert vegetation. Pages 869-889 in: M. G. Barbour and J. Major, editors. Terrestrial vegetation of California. John Wiley and Sons, New York.
  • CNPS [California Native Plant Society]. 2015-2017. A manual of California vegetation [online]. California Native Plant Society, Sacramento, CA. [http://vegetation.cnps.org/].
  • Cornett, J. W. 1987. Cold tolerance in the desert fan palm, Washingtonia filifera (Arecaceae). Madroño 34:57-62.
  • Cornett, J. W. 1988. Naturalized populations of the desert fan palm, Washingtonia filifera, in Death Valley National Monument. Pages 167-174 in: C. A. Hall and V. Doyle-Jones, editors. Plant biology of eastern California. University of California, White Mountain Research Station, Los Angeles, CA.
  • Cornett, J. W. 1989. Desert palm oasis. Palm Springs Desert Museum. Companion Press, Santa Barbara, CA.
  • Evens, J. M., D. Roach-McIntosh, and D. Stout. 2012. Vegetation descriptions for Joshua Tree National Park. Unpublished report submitted to USDI, National Park Service, Mojave Desert Inventory and Monitoring Network. California Native Plant Society, Sacramento, CA.
  • 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.
  • Holland, R. F. 1986b. Preliminary descriptions of the terrestrial natural communities of California. Unpublished report prepared for the California Department of Fish and Game, Nongame-Heritage Program and Natural Diversity Database, Sacramento. 156 pp.
  • Howard, J. L. 1992b. Washingtonia filifera. In: Fire Effects Information System [Online]. USDA Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). [http://www.fs.fed.us/database/feis/]
  • Keeler-Wolf, T., C. Roye, and K. Lewis. 1998a. Vegetation mapping and classification of the Anza-Borrego Desert State Park, California. Unpublished report on file at California Natural Diversity Database, California Department Fish and Game, Sacramento.
  • La Doux, T., C. Lea, and E. Babich. 2013. A summary of the Joshua Tree National Park Vegetation Mapping Project: NPS Vegetation Inventory Program. Natural Resource Technical Report NPS/JOTR/NRTR--2013/723. National Park Service, Fort Collins, CO. 839 pp.
  • MacMahon, J. A. 1988. Warm deserts. Pages 232-264 in: M. G. Barbour and W. D. Billings, editors. North American terrestrial vegetation. Cambridge University Press, New York.
  • McClintock, E. 1978. The Washington fan palm. Fremontia 6:3-5.
  • Minckley, W. L., and D. E. Brown. 1982. Part 6. Wetlands. Page 342 in: F. S. Crosswhite, editor. Biotic communities of the American Southwest: United States and Mexico. The University of Arizona Press, Tucson, AZ.
  • Paysen, T. E., J. A. Derby, H. Black, Jr., V. C. Bleich, and J. W. Mincks. 1980. A vegetation classification system applied to southern California. General Technical Report PSW-45. USDA Forest Service, USDA Forest Service, Pacific Southwest Research Station, Berkeley, CA.
  • Sawyer, J. O., and T. Keeler-Wolf. 1995. A manual of California vegetation. California Native Plant Society, Sacramento. 471 pp.
  • Sawyer, J. O., T. Keeler-Wolf, and J. Evens. 2009. A manual of California vegetation. Second edition. California Native Plant Society, Sacramento CA. 1300 pp.
  • Szaro, R. C. 1989. Riparian forest and scrubland community types of Arizona and New Mexico. Desert Plants Special Issue 9(3-4):70-139.