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A3201 Ephedra viridis Colorado Plateau Shrubland Alliance
Type Concept Sentence: Low shrublands and shrub-herbaceous vegetation of the Colorado Plateau dominated by Ephedra viridis.
Common (Translated Scientific) Name: Mormon-tea Colorado Plateau Shrubland Alliance
Colloquial Name: Colorado Plateau Mormon-tea Shrubland
Hierarchy Level: Alliance
Type Concept: The vegetation is characterized by a sparse to moderately dense shrub layer dominated by xeromorphic evergreen microphyllous shrub Ephedra viridis. Artemisia tridentata or Tetradymia canescens may be present to codominant in some stands of this alliance. A variety of other shrubs may be present with low cover, such as Acacia greggii, Agave spp., Atriplex canescens, Coleogyne ramosissima, Encelia farinosa, the dwarf-shrub Gutierrezia sarothrae, and cacti Echinocereus engelmannii, Ferocactus cylindraceus, Opuntia polyacantha var. erinacea, Opuntia polyacantha var. polyacantha, and Sclerocactus whipplei. The herbaceous layer is sparse to moderately dense, in some stands being more prominent than the shrubs, and is usually dominated by perennial bunchgrasses such as Achnatherum hymenoides, Bouteloua gracilis, Hesperostipa comata, Pleuraphis jamesii, or the exotic annual grass Bromus tectorum. Other grasses such as Aristida purpurea, Muhlenbergia pungens, Sporobolus airoides, and Sporobolus cryptandrus may be present depending on the site. Forb cover is generally sparse but may be surprisingly diverse. Biological crusts are often present and provide up to 25% cover. Stands of this alliance occur in the Colorado Plateau and Great Basin and are found on dry, rocky, gravelly or sandy sites in valleys and washes, and on slopes, alluvial fans, mesas, and foothills from 1380 to 2020 m elevation. Slopes are gentle to moderately steep (1-45%).
Diagnostic Characteristics: Sparse to moderately dense (10-60% cover) shrublands and shrub-herbaceous vegetation of the Colorado Plateau and Great Basin dominated by Ephedra viridis in association with other Colorado Plateau shrub and grass species.
Rationale for Nominal Species or Physiognomic Features: No Data Available
Classification Comments: Some stands of the vegetation in this alliance may be too sparse to classify as a shrubland.
Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: Vegetation included in this alliance has sparse to moderately dense woody cover dominated by xeromorphic broad-leaved and microphyllous evergreen shrubs (0.3-1 m tall). Sparse to dense cover of medium-tall bunch grasses and scattered cacti is also present. Annual grasses and forbs are seasonally present.
Floristics: Stands of this alliance may be shrub or shrub-herbaceous in structure. The shrub layer is characterized by a sparse to moderately dense shrub layer dominated by xeromorphic evergreen microphyllous shrub Ephedra viridis. Artemisia tridentata or Tetradymia canescens may be present to codominant in some stands of this alliance. A variety of other shrubs may be present with low cover, such as Acacia greggii, Agave spp., Atriplex canescens, Coleogyne ramosissima, Encelia farinosa, the dwarf-shrub Gutierrezia sarothrae, and cacti Echinocereus engelmannii, Ferocactus cylindraceus, Opuntia polyacantha var. erinacea (= Opuntia erinacea), Opuntia polyacantha var. polyacantha, and Sclerocactus whipplei. The herbaceous layer is sparse to moderately dense and may be more prominent than the shrubs. It is usually dominated by perennial bunchgrasses such as Achnatherum hymenoides, Bouteloua gracilis, Hesperostipa comata, Pleuraphis jamesii, Pleuraphis rigida, or the exotic annual grass Bromus tectorum. Other grasses such as Aristida purpurea, Muhlenbergia pungens, Sporobolus airoides, and Sporobolus cryptandrus may be present depending on the site. Forb cover is generally sparse but may be surprisingly diverse. Biological crusts are often present and provide up to 25% cover.
Dynamics: Ephedra viridis is known to sprout vigorously from the roots or woody rootcrowns or establish by seed following fire (Anderson 2001b). These fire adaptations may favor it over more fire-sensitive species such as Coleogyne ramosissima.
Environmental Description: Stands of this alliance occur in semi-arid environments. Total mean annual precipitation is approximately 25 cm. Stands are found on dry, rocky or sandy sites in valleys and washes, and on slopes, alluvial fans, mesas, and foothills. In the Colorado Plateau, stands are reported from 1380 to 2020 m elevation and occur on sand dunes and sandsheets deposited on plateaus, benches and valley floors. Sites occupy gentle to moderately steep slopes (1-45%). The unvegetated surface has high exposure of bare soil and low to moderate cover of litter; biological soil crusts provide up to 30% cover. Soils are rapidly drained, fine sandy loam, loamy sand, and sandy clay soils derived from sandstones and shales, eolian deposits and alluvium. In the Grand Canyon, sites occur on moderate to steep northern slopes, the most mesic slopes of the Inner Gorge. Elevation ranges from 580-980 m. The soils are shallow, coarse-textured and rocky, and derived from limestone, sandstone and igneous rocks.
Geographic Range: This alliance is restricted to the Colorado Plateau of Utah and Colorado.
Nations: US
States/Provinces: AZ, CA, CO, NV, UT
Plot Analysis Summary:
http://vegbank.org/natureserve/ELEMENT_GLOBAL.2.899325
Confidence Level: Low
Confidence Level Comments: No Data Available
Grank: GNR
Greasons: No Data Available
Concept Lineage: A.858, A.1543
Predecessors: No Data Available
Obsolete Names: No Data Available
Obsolete Parents: No Data Available
Synonomy: ? Ephedra viridis - Hilaria rigida - Acacia greggii Shrubland Association (Warren et al. 1982) [Stands were described from the Grand Canyon.]
- Anderson, M. D. 2001b. Ephedra viridis. In: Fire Effects Information System [Online]. USDA Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). [http://www.fs.fed.us/database/feis/] (accessed 15 October 2007 and 19 June 2011).
- 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.
- 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.