Print Report
A3174 Atriplex polycarpa Scrub Alliance
Type Concept Sentence: Shrublands in this alliance occur in desert valleys, basins, playas, bajadas, foothills and plains characterized by a sparse to moderately dense shrub layer dominated or codominated by Atriplex polycarpa.
Common (Translated Scientific) Name: Cattle Saltbush Scrub Alliance
Colloquial Name: Cattle Saltbush Scrub
Hierarchy Level: Alliance
Type Concept: Shrublands in this alliance occur in desert valleys, basins, playas, bajadas, foothills and plains in southern New Mexico, Nevada and southern California. The vegetation included in this alliance is characterized by a sparse to moderately dense shrub layer dominated or codominated by Atriplex polycarpa. Shrub associates may include Larrea tridentata, Ambrosia dumosa, Eriogonum fasciculatum, Hymenoclea salsola, Atriplex canescens, Atriplex confertifolia, Gutierrezia sarothrae, and Suaeda moquinii. Perennial graminoids are present to abundant in some habitats and may include Distichlis spicata, Pleuraphis mutica, and Sporobolus spp. Sites are generally flat to gently sloping and moderately saline, but the alliance also occurs on rolling to hilly fans and slopes.
Diagnostic Characteristics: Atriplex polycarpa >2% absolute cover in the shrub canopy; >50% relative cover in the shrub canopy (Keeler-Wolf et al. 1998, Thomas et al. 2004).
Rationale for Nominal Species or Physiognomic Features: No Data Available
Classification Comments: This alliance has been segregated from the previously defined Atriplex lentiformis-A. polycarpa alliance (Sawyer and Keeler-Wolf 1995). Based on plot data collected over the past 10 years, both of these species apparently segregate and form their own alliances with frequently different environmental and species characteristics.
Brown (1982a) describes stands in the Saltbush Series that are dominated by Atriplex polycarpa. No Atriplex polycarpa associations have yet been described in Arizona by ecologists. The stands described by Peterson (1984a) are too sparse to be classified as shrublands. Little other quantitative data were available.
Whitfield and Anderson (1938) describe Atriplex polycarpa-dominated stands in the Chihuahuan Desert where other characteristic shrubs include Atriplex canescens, Atriplex confertifolia, Ambrosia dumosa, Larrea tridentata, Gutierrezia sarothrae, the phreatophyte Suaeda moquinii, and perennial grasses such as Sporobolus airoides, Pleuraphis mutica, Sporobolus cryptandrus, and Muhlenbergia porteri. The perennial grass cover is possible because of the late summer rains. In the Mojave Desert, grass cover is sparse. In Death Valley (Peterson 1984a) described stands with 10% aerial cover of Atriplex polycarpa and 1% or less of Ambrosia dumosa, Larrea tridentata, and Hymenoclea salsola. Total shrubs cover was 13%. In addition to Atriplex polycarpa, stands in the California Central Valley include a variety of dune, playa or uplands species such as Distichlis spicata, Ephedra californica, Eriogonum fasciculatum, Hymenoclea salsola, Cleome isomeris (= Isomeris arborea), Isocoma acradenia, and Prosopis glandulosa (Sawyer and Keeler-Wolf 1995).
Brown (1982a) describes stands in the Saltbush Series that are dominated by Atriplex polycarpa. No Atriplex polycarpa associations have yet been described in Arizona by ecologists. The stands described by Peterson (1984a) are too sparse to be classified as shrublands. Little other quantitative data were available.
Whitfield and Anderson (1938) describe Atriplex polycarpa-dominated stands in the Chihuahuan Desert where other characteristic shrubs include Atriplex canescens, Atriplex confertifolia, Ambrosia dumosa, Larrea tridentata, Gutierrezia sarothrae, the phreatophyte Suaeda moquinii, and perennial grasses such as Sporobolus airoides, Pleuraphis mutica, Sporobolus cryptandrus, and Muhlenbergia porteri. The perennial grass cover is possible because of the late summer rains. In the Mojave Desert, grass cover is sparse. In Death Valley (Peterson 1984a) described stands with 10% aerial cover of Atriplex polycarpa and 1% or less of Ambrosia dumosa, Larrea tridentata, and Hymenoclea salsola. Total shrubs cover was 13%. In addition to Atriplex polycarpa, stands in the California Central Valley include a variety of dune, playa or uplands species such as Distichlis spicata, Ephedra californica, Eriogonum fasciculatum, Hymenoclea salsola, Cleome isomeris (= Isomeris arborea), Isocoma acradenia, and Prosopis glandulosa (Sawyer and Keeler-Wolf 1995).
Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: Vegetation included in this alliance has a sparse to moderately dense woody layer dominated by facultative deciduous and microphyllous evergreen shrubs. The usually sparse herbaceous layer has a few perennial species of grasses and forbs with sometimes abundant cover of seasonally present annual grasses and forbs.
Floristics: The vegetation has a sparse to moderately dense woody layer usually less than 1 m tall, but occasionally over 2 m tall in mixed-shrub stands. Atriplex polycarpa, a facultative deciduous xeromorphic shrub, is the dominant species and may occur in nearly pure stands. Other characteristic shrubs may include Larrea tridentata, Ambrosia dumosa, and Hymenoclea salsola. Perennial graminoids such as Distichlis spicata, Pleuraphis mutica (= Hilaria mutica), and Sporobolus spp. may be present and abundant in some habitats. Exotic annual grasses may dominate the understory in stands in California. Secondary species vary widely depending on site characteristics and geographic location.
Dynamics: Atriplex polycarpa is a facultative phreatophyte and occurs on moderately saline soil (<2%) just above the water table or xeric non-saline upland sites (Barbour and Major 1977). It has limited salt tolerance and is very drought-tolerant (Barbour and Major 1977). These two factors interact to control water stress in plants and define habitat boundaries.
Environmental Description: Shrublands in this alliance occur in desert valleys, basins, playas, bajadas, foothills and plains in southern New Mexico, Nevada and southern California. Climate is arid to semi-arid with hot summers. Sites are generally flat to gently sloping and moderately saline, but the alliance also occurs on rolling to hilly fans and slopes. Other characteristics vary by site and region. In the Chihuahuan Desert (1200-1500 m elevation), annual precipitation has a bimodal distribution with about half the precipitation occurring during the late summer months. Sites occur on lower foothills and plains. Soils are fine-textured, alkaline and typically saline.
Geographic Range: This alliance includes shrublands from valleys and basins in the Chihuahuan, Mojave and Sonoran deserts, and in the southern part of the Great Central Valley of California.
Nations: US
States/Provinces: CA, NM, NV
Plot Analysis Summary:
http://vegbank.org/natureserve/ELEMENT_GLOBAL.2.899299
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 | A3174 Cattle Saltbush Scrub Alliance | A3174 | 3.B.1.Ne.5.b |
| Association | CEGL001318 Cattle Saltbush Shrubland | CEGL001318 | 3.B.1.Ne.5.b |
| Association | CEGL001319 Cattle Saltbush / Tobosa Grass Shrubland | CEGL001319 | 3.B.1.Ne.5.b |
Concept Lineage: equivalent to A.873
Predecessors: No Data Available
Obsolete Names: No Data Available
Obsolete Parents: No Data Available
Synonomy: = Atriplex polycarpa (Allscale scrub) Alliance (Sawyer et al. 2009) [36.340.00]
= Atriplex polycarpa Alliance (Allscale scrub) (Buck-Diaz et al. 2012)
= Atriplex polycarpa Shrubland Alliance (Evens et al. 2014)
= Atriplex polycarpa Alliance (Allscale scrub) (Buck-Diaz et al. 2012)
= Atriplex polycarpa Shrubland Alliance (Evens et al. 2014)
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