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A4163 Encelia actonii - Encelia virginensis - Viguiera reticulata Desert Scrub Alliance

Type Concept Sentence: This shrubland alliance forms an open to intermittent shrub layer with Encelia actonii, Encelia virginensis, or Viguiera reticulata is dominant or codominant in the shrub layer and Hymenoclea salsola is characteristically present at lower cover. The alliance is found in the Mojave Desert of California primarily on drainages, but occasionally occurs on scree slopes with recent disturbance. Habitats include intermittently flooded arroyos, canyons, and washes adjacent to alluvial fans, road cuts, and other substrates with recent disturbance.

Common (Translated Scientific) Name: Acton''s Brittlebush - Virgin River Brittlebush - Netvein Goldeneye Desert Scrub Alliance

Colloquial Name: Brittlebush - Goldeneye Desert Scrub

Hierarchy Level:  Alliance

Type Concept: This shrubland alliance forms an open to intermittent shrub layer. The emergent tree layer, when present, is sparse to open, and the herbaceous layer is also sparse to open. Encelia actonii, Encelia virginensis, or Viguiera reticulata is dominant or codominant in the shrub layer and Hymenoclea salsola is characteristically present at lower cover. Ambrosia dumosa, Cylindropuntia acanthocarpa, Echinocereus engelmannii, Ephedra nevadensis, Eriogonum fasciculatum, Gutierrezia microcephala, Larrea tridentata, Lycium andersonii, Salazaria mexicana, Salvia dorrii, and Stephanomeria pauciflora are often present. Bromus rubens, Eriogonum inflatum, Erodium cicutarium, and Sphaeralcea ambigua are often to characteristically present in the herbaceous layer. The alliance is found in the Mojave Desert of California primarily on drainages, but occasionally occurs on scree slopes with recent disturbance. Habitats include intermittently flooded arroyos, canyons, and washes adjacent to alluvial fans, road cuts, and other substrates with recent disturbance. Elevations range from 300 to 1900 m. Soils are often derived from sandstone, typically calcareous alluvium, though may be derived from other substrates, including rhyolite, and they have a variety of textures, ranging from clay loam to sand to silt loam.

Diagnostic Characteristics: Encelia actonii or Encelia virginensis =2% absolute cover in the shrub canopy; no other species with greater or equal cover (Thomas et al. 2004); Encelia actonii or Encelia virginensis =2% absolute cover in the shrub canopy; Salvia dorrii may have equal or greater cover (Evens 2000); or Viguiera reticulata =2% absolute cover and other shrubs equal or less cover in the shrub canopy (Thomas et al. 2004).

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: Encelia virginensis and Encelia actonii commonly occur as associates on uplands in several alliances at middle and upper elevations in California''s hot deserts. The alliance is locally common in washes where irregular flooding occurs, particularly on cobbled calcareous substrates. Stands in the late spring and summer have spectacular shows of their full golden flowers, lining the washes as they radiate from the mountain ranges.

Stands of Viguiera reticulata typically occur in medium-gradient, rocky arroyos in the desert mountains of the southeastern portions California. They are small (under 0.5 ha) and appear restricted to calcareous substrates (dolomite, limestone, and marble) where irregular flooding occurs. Stands are usually on small terraces adjacent to the most active parts of washes. Stands of ~Prunus fasciculata - Salazaria mexicana Northern Mojave Desert Wash Scrub Alliance (A4185)$$, ~Ephedra californica - Ephedra trifurca Desert Wash Scrub Alliance (A2536)$$, ~Ericameria paniculata Mojave Desert Wash Scrub Alliance (A2509)$$, and ~Acacia greggii - Hyptis emoryi - Justicia californica Desert Wash Scrub Alliance (A4187)$$ occupy similar settings.

Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: No Data Available

Floristics: The alliance forms an open to intermittent shrub layer with the overall shrub cover ranging from 9 to 40%. The tree layer is typically sparse, and the herb layer is sparse to open. Nonvascular plants are typically sparse to open. The dominant or codominant shrub is either Encelia actonii, Encelia virginensis, or Viguiera reticulata is the dominant and characteristic shrub of this alliance. Hymenoclea salsola is characteristically present at lower cover. Ambrosia dumosa, Echinocereus engelmannii, Ephedra nevadensis, Eriogonum fasciculatum, Gutierrezia microcephala, Hymenoclea salsola, Larrea tridentata, Lycium andersonii, Cylindropuntia acanthocarpa, Salazaria mexicana, Salvia dorrii, and Stephanomeria pauciflora are often present. Bromus rubens, Eriogonum inflatum, Erodium cicutarium, and Sphaeralcea ambigua are often to characteristically present in the herbaceous layer.

Dynamics:  Stands occur on gravelly and cobbly washes with intermittent flooding. Plants also can occur in other disturbed sites. They increase with increasing disturbance and are replaced in areas lacking recurring disturbance. The two Encelia species can sometimes be difficult to tell apart. Viguiera reticulata stands appear restricted to calcareous substrates (dolomite, limestone, and marble) where irregular flooding occurs. Stands are usually on small terraces adjacent to the most active parts of washes or directly above on colluvial slopes.

This alliance is primarily disturbed by fluvial processes rather than fire. Most stands are open and rocky; however, fire could affect them in years where introduced or native annuals form dense cover and sufficient flashy fuels. Viguiera reticulata may sprout after fire and other disturbances.

Encelia virginensis is important forage for the desert tortoise, and it has been used in restoration projects (Esser 1993c). OHV activity occurs in some washes where Viguiera reticulata grows. However, many of the stands are in remote canyons that receive little recreational activity.
Environmental Description:  The alliance occurs at mid to high elevations (approximately 600-1650 m) usually in dry washes and sometimes on steep rocky slopes with recent disturbance. The alliance occurs at all aspects. The soils are typically calcareous alluvium though may be derived from other substrates including rhyolite, and textures range from sand to loam.
Geographic Range: The alliance is well-defined in sampling at Death Valley National Monument and Mojave National Preserve in California where it is found scattered throughout at mid to upper elevations. It is also known from the Colorado Desert, southeastern Great Basin, and southern California mountains and valleys.

Nations: US

States/Provinces:  CA, NV


Confidence Level: Low

Confidence Level Comments: No Data Available
Grank: G4

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.7 North American Warm-Desert Xeric-Riparian Scrub Macrogroup M092 3.A.2.Na.7
Group 3.A.2.Na.7.a Desert-willow - Apache Plume - Desert Almond Desert Wash & Colluvial Slope Group G541 3.A.2.Na.7.a
Alliance A4163 Acton''s Brittlebush - Virgin River Brittlebush - Netvein Goldeneye Desert Scrub Alliance A4163 3.A.2.Na.7.a
Association CEGL001335 Virgin River Brittlebush Shrubland CEGL001335 3.A.2.Na.7.a
Association CEGL002962 Netvein Goldeneye Shrubland CEGL002962 3.A.2.Na.7.a
Association CEGL005748 Acton''s Brittlebush Desert Shrubland CEGL005748 3.A.2.Na.7.a
Concept Lineage: No Data Available

Predecessors: No Data Available

Obsolete Names: No Data Available

Obsolete Parents: No Data Available
Synonomy: > Encelia (actonii, virginensis) Shrubland Alliance (Evens et al. 2014)
> Encelia virginensis (Virgin River brittle brush scrub) Alliance (Sawyer et al. 2009) [33.025.00]
> Encelia virginensis Alliance (Brittle brush scrub) (Buck-Diaz et al. 2012)
> Encelia virginensis Shrubland Alliance (Evens et al. 2012)
> Encelia (actonii, virginensis) Shrubland Alliance (CNPS 2017) [33.025.00]
> Viguiera reticulata (Net-veined goldeneye scrub) Alliance (Sawyer et al. 2009) [33.033.00]
> Viguiera reticulata Shrubland Alliance (CNPS 2017) [33.033.00]
> Viguiera reticulata Shrubland Alliance (Evens et al. 2014)
< Creosote bush series (Sawyer and Keeler-Wolf 1995)
>< Mojave Creosote Bush Scrub (#34100) (Holland 1986b)
>< Mojave Desert Wash Scrub (#63700) (Holland 1986b)
>< Sonoran Creosote Bush Scrub (#33100) (Holland 1986b)
Concept Author(s): J. Evens and M.S. Reid, after Sawyer et al. (2009)

Author of Description: J. Evens

Acknowledgements: No Data Available

Version Date: 01-23-15
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