Print Report

A3171 Grayia spinosa Scrub Alliance

Type Concept Sentence: This alliance occurs in the Great Basin and the eastern Mojave Desert, and is characterized by a sparse to moderately dense shrub layer of Grayia spinosa. Other shrubs are species of Mojavean or Great Basin affinities.

Common (Translated Scientific) Name: Spiny Hopsage Scrub Alliance

Colloquial Name: Spiny Hopsage Scrub

Hierarchy Level:  Alliance

Type Concept: Vegetation in this alliance occurs throughout the lower to middle elevations (600-1600 m) of the Great Basin and the eastern Mojave Desert. The vegetation is more drought-tolerant than Artemisia tridentata-dominated communities and typically occurs where local climate or salty soils create high moisture stress. This alliance is characterized by a sparse to moderately dense shrub layer of Grayia spinosa. Shrub associates include Artemisia nova, Artemisia tridentata, Atriplex confertifolia, Atriplex canescens, Chrysothamnus spp., Coleogyne ramosissima, Ephedra nevadensis, Ephedra viridis, Larrea tridentata, Picrothamnus desertorum, and Prunus andersonii. The herbaceous layer is typically sparse with Achnatherum hymenoides, Achnatherum speciosum, Elymus elymoides, Navarretia spp., Pleuraphis jamesii, and Poa secunda being common associates. Stands usually occur on mountain slopes or alluvial fans bordering intermountain basins. Soils are highly variable, but are generally coarse-textured and well-drained, and often alkaline.

Diagnostic Characteristics: Vegetation in this alliance can be differentiated from other alliances by the strong dominance of Grayia spinosa in the shrub layer, and its broad distribution in non-wetland locations.

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: During the ecological group revision, all Grayia spinosa associations were placed across several groups. The associations within this alliance had been split across ~Intermountain Shadscale - Saltbush Scrub Group (G300)$$ and ~Mojave Mid-Elevation Mixed Desert Scrub Group (G296)$$. They have been combined within G300 and this alliance as they appear to represent inclusions within the greater matrix-forming communities of the shadscale - saltbush communities.

Currently there are no associations placed in this alliance from California. Sawyer and Keeler-Wolf (1995) do report a Hop-sage Series that is included as part of this alliance. Further classification and inventory work are needed to develop the association-level classification of this alliance.

Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: These communities are characterized by somewhat low to moderate cover (15-40%) of cold-deciduous or evergreen shrubs. The herbaceous layer is typically sparse (<20% cover) and dominated by cespitose perennial grasses or annual forbs and grasses. Scattered trees may form a sparse (0-10%) emergent layer in some stands, especially at the upper elevation margin and in the southwestern part of the range.

Floristics: Species found in southern stands include Atriplex canescens, Atriplex confertifolia, Coleogyne ramosissima, Ephedra nevadensis, Larrea tridentata, and Picrothamnus desertorum (= Artemisia spinescens). Occasionally, scattered individuals of Yucca brevifolia may be emergent through the shrub layer. The herbaceous layer in these xeric southern stands is typically sparse with Achnatherum hymenoides (= Oryzopsis hymenoides), Achnatherum speciosum (= Stipa speciosa), Eriogonum spp., Navarretia spp., and Pleuraphis jamesii (= Hilaria jamesii) being common associates. Northward, and at higher elevations, the Mojavean element drops out and common shrub associates include Artemisia nova, Artemisia tridentata, Chrysothamnus spp., Ephedra viridis, and Prunus andersonii. Herbaceous associates include Elymus elymoides, Festuca spp., and Poa secunda.

Dynamics:  Grayia spinosa shrubs concentrate chemical elements in their leaves and fruits, and soils beneath the shrubs often show high levels of magnesium and potassium. Seeds remain viable for long periods (4 years or more) before germination (Mozingo 1987). Due to its wide geographic range, the species may demonstrate considerable ecotypic variation. For example, seeds from Mojave Desert individuals can germinate at 40°C, but seeds from Great Basin plants cannot germinate at that high temperature (Mozingo 1987).
Environmental Description:  Vegetation in this alliance occurs throughout the lower to middle elevations (600-1600 m) of the Great Basin and the eastern Mojave Desert, usually on mountain slopes or alluvial fans bordering intermountain basins. The climate is arid to semi-arid with precipitation ranging from 15-30 cm annually. Winter precipitation dominates in the western area, with summer rain becoming more important eastward. Temperatures are continental, with large annual and diurnal ranges. Soils are highly variable, but are generally coarse-textured and well-drained, and often alkaline.
Geographic Range: This alliance occurs throughout the Great Basin, Columbia Plateau, and eastern Mojave regions of Colorado, Utah, Nevada, Oregon, Washington, and eastern California. It is most extensive in the southwestern portion of the Great Basin.

Nations: US

States/Provinces:  CA, CO, NV, OR, UT, WA


Confidence Level: Low

Confidence Level Comments: No Data Available
Grank: GNR

Greasons: No Data Available
Type Name Database Code Classification Code
Class 3 Desert & Semi-Desert Class C03 3
Subclass 3.B Cool Semi-Desert Scrub & Grassland Subclass S11 3.B
Formation 3.B.1 Cool Semi-Desert Scrub & Grassland Formation F033 3.B.1
Division 3.B.1.Ne Western North American Cool Semi-Desert Scrub & Grassland Division D040 3.B.1.Ne
Macrogroup 3.B.1.Ne.5 Shadscale Saltbush - Fourwing Saltbush - Mat Saltbush Great Basin Scrub Macrogroup M093 3.B.1.Ne.5
Group 3.B.1.Ne.5.b Shadscale Saltbush - Fourwing Saltbush - Spiny Hopsage Scrub Group G300 3.B.1.Ne.5.b
Alliance A3171 Spiny Hopsage Scrub Alliance A3171 3.B.1.Ne.5.b
Association CEGL001344 Spiny Hopsage / Black Sagebrush / Desert Needlegrass Shrubland CEGL001344 3.B.1.Ne.5.b
Association CEGL001345 Spiny Hopsage / Bud Sagebrush Shrubland CEGL001345 3.B.1.Ne.5.b
Association CEGL001350 Spiny Hopsage / Indian Ricegrass Shrubland CEGL001350 3.B.1.Ne.5.b
Association CEGL001351 Spiny Hopsage / Sandberg Bluegrass Shrubland CEGL001351 3.B.1.Ne.5.b
Association CEGL001352 Spiny Hopsage - Desert Peach Shrubland CEGL001352 3.B.1.Ne.5.b
Association CEGL002358 Spiny Hopsage Shrubland CEGL002358 3.B.1.Ne.5.b
Association CEGL002681 Spiny Hopsage / Thurber''s Needlegrass Shrubland CEGL002681 3.B.1.Ne.5.b
Concept Lineage: A.1038, in part

Predecessors: No Data Available

Obsolete Names: No Data Available

Obsolete Parents: No Data Available
Synonomy: = Grayia spinosa (Spiny hop sage scrub) Alliance (Sawyer et al. 2009) [33.180.00]
= Grayia spinosa Shrubland Alliance (Evens et al. 2014)
= Grayia spinosa Shrubland Alliance (Evens et al. 2012)
= Grayia spinosa Shrubland Alliance (CNPS 2017) [33.180.00]
= Hop-sage series (Sawyer and Keeler-Wolf 1995)
< Shadscale Scrub (#36140) (Holland 1986b)
Concept Author(s): M.S. Reid, D. Sarr, G. Kittel, in Faber-Langendoen et al. (2013)

Author of Description: M.E. Hall

Acknowledgements: No Data Available

Version Date: 11-11-16
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