Print Report

A0872 Atriplex hymenelytra Scrub Alliance

Type Concept Sentence: Stands included in this alliance occur in valleys, bajadas and lower slopes of mountains in the Mojave Desert and characterized by a very sparse canopy of Atriplex hymenelytra.

Common (Translated Scientific) Name: Desert-holly Scrub Alliance

Colloquial Name: Desert-holly Scrub

Hierarchy Level:  Alliance

Type Concept: Stands included in this alliance occur in valleys, bajadas and lower slopes of mountains in the Mojave Desert and characterized by a very sparse canopy of Atriplex hymenelytra. Vegetation included in this alliance has a very sparse canopy of Atriplex hymenelytra less than 1 m tall with scattered clumps of Chamaesyce parishii and Tidestromia oblongifolia. More mesic sites in drainages may support additional shrubs, including Ambrosia dumosa, Baccharis sergiloides, Bebbia juncea, Dalea mollissima, Eriogonum inflatum, Hymenoclea salsola, and Larrea tridentata. During wet years, annual forbs may be present. Adjacent vegetation is generally shrublands dominated by Ambrosia dumosa and Larrea tridentata. Sites are very arid because of topography or salts. The alliance is commonly found along drainages that dissect west-facing bajadas and on western slopes of mountains. Topography is typically flat and rolling to moderately sloping. There are large areas of desert pavement with very sparse vegetation. Soils are deep, well-drained, alkaline, and coarse-textured.

Diagnostic Characteristics: Vegetation of the alliance is characterized by short-statured shrubs <1 m tall with a sparse canopy of the shrub Atriplex hymenelytra.

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: The alliance is floristically and structurally simple. It commonly exists in desert pavement areas where vegetation is very sparse; it also occurs on rough lava and limestone deposits with skeletal soils and in heavy alkaline sediments. Seral relationships are relatively simple in the alliance''s harsh upland environments. Natural disturbance comes mostly as shifts in moisture availability: a series of drier years may eliminate individual shrubs, leaving little more than an ephemeral herb seed bank. A series of wetter years may shift stands toward other desert alliances, while tolerance of bare mineral substrate with low nutritional value and no apparent mycorrhizal associations confer an advantage for Atriplex hymenelytra in colonizing washes and road cuts. Tidestromia oblongifolia, one of the most common associates, also grows in disturbed, OHV sites. Severe degradation of upland stands can result in stands of the Tidestromia oblongifolia.

Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: These communities are characterized by sparse cover of cold-deciduous or evergreen shrubs. The herbaceous layer is typically sparse with annual forbs which are variable year to year.

Floristics: Vegetation included in this Mojave Desert alliance has a very sparse canopy of Atriplex hymenelytra less than 1 m tall with scattered clumps of Tidestromia oblongifolia and Chamaesyce parishii. More mesic sites in drainages may support additional perennials, including Ambrosia dumosa, Baccharis sergiloides, Dalea mollissima, Bebbia juncea, Eriogonum inflatum, Hymenoclea salsola, and Larrea tridentata. During wet years, annual forbs such as Atrichoseris platyphylla, Camissonia spp., Chaenactis carphoclinia, Cryptantha spp., Geraea canescens, Monoptilon bellioides, Phacelia calthifolia, Psathyrotes spp., and many other species may be present.

Dynamics:  Like many species of Atriplex, Atriplex hymenelytra is adapted to tolerate extremely arid habitats. However, it is one of the few species that is able to exist on the west-facing bajadas and hillslopes below 600 m of the Black Mountains in Death Valley National Park. Little other information is available on these stands.
Environmental Description:  Stands included in this alliance occur in valleys, bajadas and lower slopes of mountains in the Mojave Desert from -75 to 1400 m in elevation. Climate is characterized by hot dry summers. The rain occurs mostly in winter. Annual precipitation varies widely from year to year with mean annual precipitation of approximately 10 cm depending on elevation and location. Sites are very arid because of topography or salts. The alliance is commonly found along drainages that dissect the west-facing bajadas and on western slopes of mountains. Topography is typically flat and rolling to moderately sloping. There are large areas of desert pavement with very sparse vegetation. Soils are deep, well-drained, alkaline, and coarse-textured (very gravelly, fine sandy loams) with boulders and cobbles. Soils are derived from alluvium, colluvium and residuum typically from carbonitic rocks such as limestone, but deposits may also be from metamorphic, igneous and other sedimentary rocks. Adjacent vegetation is generally shrublands dominated by Larrea tridentata or Ambrosia dumosa.
Geographic Range: Stands in this alliance have been described from the Mojave Desert in California and Nevada. It may also occur in deserts in Arizona, Utah and northern Mexico.

Nations: MX?,US

States/Provinces:  AZ, CA, NV, UT?


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.A Warm Desert & Semi-Desert Woodland, Scrub & Grassland Subclass S06 3.A
Formation 3.A.2 Warm Desert & Semi-Desert Scrub & Grassland Formation F015 3.A.2
Division 3.A.2.Na North American Warm Desert Scrub & Grassland Division D039 3.A.2.Na
Macrogroup 3.A.2.Na.6 Ocotillo - Desert-holly - Watson''s Amaranth North American Rock Vegetation Macrogroup M117 3.A.2.Na.6
Group 3.A.2.Na.6.a Ocotillo - Bear-grass species - Desert-holly Rock Vegetation Group G569 3.A.2.Na.6.a
Alliance A0872 Desert-holly Scrub Alliance A0872 3.A.2.Na.6.a
Association CEGL001264 Desert-holly - Creosotebush Shrubland CEGL001264 3.A.2.Na.6.a
Association CEGL001317 Desert-holly Shrubland CEGL001317 3.A.2.Na.6.a
Association CEGL005740 Desert-holly - Burrobush Shrubland CEGL005740 3.A.2.Na.6.a
Association CEGL005741 Desert-holly - Arizona Honeysweet Shrubland CEGL005741 3.A.2.Na.6.a
Concept Lineage: equivalent to A.872

Predecessors: No Data Available

Obsolete Names: No Data Available

Obsolete Parents: No Data Available
Synonomy: = Atriplex hymenelytra (Desert holly scrub) Alliance (Sawyer et al. 2009) [36.330.00]
= Atriplex hymenelytra Shrubland Alliance (Evens et al. 2014)
= Atriplex hymenelytra Shrubland Alliance (Evens et al. 2012)
= Atriplex hymenelytra Shrubland Alliance (CNPS 2017) [36.330.00]
< Desert Saltbush Scrub (#36110) (Holland 1986b)
= Desert holly series (Sawyer and Keeler-Wolf 1995)
Concept Author(s): M.E. Hall, in Faber-Langendoen et al. (2013)

Author of Description: M.E. Hall

Acknowledgements: No Data Available

Version Date: 01-08-14
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