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CEGL000954 Ambrosia dumosa - Ephedra (fasciculata, nevadensis) Dwarf-shrubland

The U.S. National
Vegetation Classification
Type Concept Sentence:
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Common (Translated Scientific) Name: Burrobush - (Arizona Joint-fir, Nevada Joint-fir) Dwarf-shrubland
Colloquial Name:
Hierarchy Level: Association
Type Concept: This white bursage shrubland association is currently described from Grand Canyon National Park and Grand Canyon-Parashant National Monument in Arizona. More survey and classification work are needed to fully characterize this type. It occurs primarily on sideslopes and ridgetops at 650 to 750 m (2150-2500 feet) elevation, but may occur throughout a broader elevational range than was documented by the classification plots. It is typically found on moderately sloping gradients (10-15°), but has also been seen on nearly flat surfaces. Soils are well- to rapidly-drained sandy clays that occasionally obscure the bedrock below. The underlying geology is usually sandstone. Vegetation is characterized and codominated by the dwarf-shrub Ambrosia dumosa and the short shrub Ephedra fasciculata. In some stands, Ephedra fasciculata is absent and Ephedra nevadensis takes its place as a codominant. Tall shrubs are rare, but some stands are occasionally contain Acacia greggii. The short-shrub layer also frequently includes Ferocactus cylindraceus. The only other dwarf-shrub that appears with significant cover is Gutierrezia sarothrae. Vulpia octoflora and Pleuraphis jamesii are frequently present in a sparse graminoid layer. Erodium cicutarium, Lepidium densiflorum, and Machaeranthera pinnatifida occur with some regularity in a relatively poorly-developed forb layer.
Diagnostic Characteristics: No Data Available
Rationale for Nominal Species or Physiognomic Features:
Classification Comments: No Data Available
Similar NVC Types:
Ambrosia dumosa - Encelia farinosa Dwarf-shrubland, note: supports a similar cover of Ambrosia dumosa and also contains Ephedra fasciculata, Ephedra nevadensis, and Encelia farinosa (which occurs more frequently and with higher cover).
Physiognomy and Structure: No Data Available
Dynamics: No Data Available
Environmental Description: No Data Available
Geographic Range: This shrubland association is currently known from Grand Canyon National Park and Grand Canyon-Parashant National Monument in Arizona. It is also reported from New Mexico. More survey work is needed to fully document its global range.
Nations: US
States/Provinces: AZ, NM
US Forest Service Ecoregions (1994/1995)
Domain Name:
Division Name:
Province Name: Colorado Plateau Semi-Desert Province
Province Code: 313    Occurrence Status: Confident or certain
Section Name: Navajo Canyonlands Section
Section Code: 313B     Occurrence Status: Confident or certain
Omernik Ecoregions:
Confidence Level: Low - Poorly Documented
Confidence Level Comments:
Grank: GNR
Concept Lineage:
Obsolete Names:
Obsolete Parents:
Synonomy: = 153.11013 Ambrosia dumosa - Ephedra nevadensis - Ferocactus acanthodes Association (Warren et al. 1982)
= Ambrosia dumosa-Ephedra nevadensis (Bourgeron and Engelking 1994)
< DRISCOLL FORMATION CODE:III.A.1.d. (Driscoll et al. 1984)
Concept Author(s): Western Ecology Group
Author of Description: R. Meszaros
Version Date: 29Jul2010
  • Bourgeron, P. S., and L. D. Engelking, editors. 1994. A preliminary vegetation classification of the western United States. Unpublished report. The Nature Conservancy, Western Heritage Task Force, Boulder, CO. 175 pp. plus appendix.
  • Driscoll, R. S., D. L. Merkel, D. L. Radloff, D. E. Snyder, and J. S. Hagihara. 1984. An ecological land classification framework for the United States. Miscellaneous Publication No. 1439. USDA Forest Service, Washington, DC. 56 pp.
  • Kearsley, M. J. C., K. Green, M. Tukman, M. Reid, M. Hall, T. J. Ayers, and K. Christie. 2015. Grand Canyon National Park-Grand Canyon / Parashant National Monument vegetation classification and mapping project. Natural Resource Report NPS/GRCA/NRR--2015/913. National Park Service, Fort Collins, CO. 75 pp. plus appendices.
  • Reid, M. S., and M. E. Hall. 2010. Vegetation classification of Grand Canyon National Park. Draft report submitted to National Park Service, Fort Collins, CO.
  • Warren, P. L., K. L. Reichhardt, D. A. Mouat, B. T. Brown, and R. R. Johnson. 1982. Vegetation of Grand Canyon National Park. Cooperative National Park Resources Studies Unit Technical Report 9. Tucson, AZ. 140 pp.
  • Western Ecology Working Group of NatureServe. No date. International Ecological Classification Standard: International Vegetation Classification. Terrestrial Vegetation. NatureServe, Boulder, CO.