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A3278 Larrea tridentata - Fouquieria splendens Upper Bajada & Rock Outcrop Desert Scrub Alliance

Type Concept Sentence: This widespread alliance occurs in the Mojave, Sonoran and Colorado deserts and is characterized by an open, xeromorphic shrub layer dominated by Larrea tridentata, Encelia farinosa, Fouquieria splendens, or Nolina bigelovii. Stands occur on alluvial fans, bajadas, upland slopes and minor washes.

Common (Translated Scientific) Name: Creosotebush - Ocotillo Upper Bajada & Rock Outcrop Desert Scrub Alliance

Colloquial Name: Creosotebush - Ocotillo Upper Bajada & Rock Outcrop Desert Scrub

Hierarchy Level:  Alliance

Type Concept: This widespread alliance occurs in the Mojave, Sonoran and Colorado deserts and extends into the transition zone with the Great Basin. The vegetation is characterized by an open, xeromorphic shrub layer dominated by Larrea tridentata, Encelia farinosa, Fouquieria splendens, or Nolina bigelovii. Other desert shrubs and dwarf-shrubs may be present to codominant, including Agave deserti, Ambrosia dumosa, Bebbia juncea, Eriogonum fasciculatum, Fagonia laevis, Ferocactus cylindraceus, Grayia spinosa, Krameria grayi, Lycium andersonii, Opuntia basilaris, Cylindropuntia bigelovii, and Peucephyllum schottii. The herbaceous layer is typically sparse with scattered Dasyochloa pulchella, Pleurocoronis pluriseta, or Stephanomeria pauciflora. Abundant annuals such as Eriogonum inflatum may be seasonally abundant. Stands occur on alluvial fans, bajadas, upland slopes and minor washes. Sites are gentle to moderately sloping. Substrates are typically well-drained, rocky soils derived from colluvium or alluvium and/or with a pavement surface.

Diagnostic Characteristics: The vegetation is characterized by an open, xeromorphic shrub layer dominated by diagnostic species Larrea tridentata, Encelia farinosa, or Fouquieria splendens. Some stands are dominated by rosette stem succulents such as Nolina bigelovii. Larrea tridentata, a late-seral indicator, is typically present to dominant.

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: This description is based on classification work done by Thomas et al. (2004) on the Mojave Ecosystem Mapping Project. This is a later-seral type as noted by the typical dominance of Larrea tridentata in contrast to ~Encelia farinosa Desert Scrub Alliance (A4215)$$, which is an early-seral type where Larrea tridentata is absent or has low cover (J. Evens pers. comm. 2017).

Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: Tall shrubs are emergent over an open shrub canopy. The herbaceous layer is sparse. Scattered emergent individual trees and shrubs, up to 5 m in height, may be present.

Floristics: The vegetation is characterized by an open, xeromorphic shrub layer dominated by Larrea tridentata, Encelia farinosa, Fouquieria splendens, or Nolina bigelovii. Other desert shrubs and dwarf-shrubs may be present to codominant, including Agave deserti, Ambrosia dumosa, Bebbia juncea, Eriogonum fasciculatum, Fagonia laevis, Ferocactus cylindraceus, Grayia spinosa, Krameria grayi, Lycium andersonii, Opuntia basilaris, Cylindropuntia bigelovii (= Opuntia bigelovii), and Peucephyllum schottii. The herbaceous layer is typically sparse with scattered Dasyochloa pulchella (= Erioneuron pulchellum), Pleurocoronis pluriseta, or Stephanomeria pauciflora. Abundant annuals such as Eriogonum inflatum may be seasonally abundant.

Dynamics:  This is a later-seral type as noted by the dominance or codominance of Larrea tridentata.
Environmental Description:  This widespread alliance occurs in the Mojave, Sonoran and Colorado deserts and extends into the transition zone with the Great Basin. Elevation generally ranges from -75 to 1400, but may extend up to 2250 m on rocky slopes. Stands occur on alluvial fans, bajadas, upland slopes and minor washes. Sites are gentle to steep slopes. Substrates are typically well-drained, rocky soils derived from colluvium or alluvium and/or with a pavement surface and often derived from granite or are of calcareous origin (Thomas 2000 et al. 2004, Sawyer et al. 2009).
Geographic Range: This alliance is found in the Mojave, Sonoran and Colorado deserts and extends into the Great Basin transition zone in southeastern Nevada.

Nations: MX?,US

States/Provinces:  AZ, CA, MXSON?, NM?, NV


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.4 Saguaro - Organ Pipe Cactus - Burrobush Mojave-Sonoran Semi-Desert Scrub Macrogroup M088 3.A.2.Na.4
Group 3.A.2.Na.4.b Creosotebush - Burrobush - Brittlebush Desert Scrub Group G295 3.A.2.Na.4.b
Alliance A3278 Creosotebush - Ocotillo Upper Bajada & Rock Outcrop Desert Scrub Alliance A3278 3.A.2.Na.4.b
Association CEGL001268 Creosotebush - Nevada Joint-fir Shrubland CEGL001268 3.A.2.Na.4.b
Association CEGL001273 Creosotebush - Beavertail Prickly-pear - Ocotillo Shrubland CEGL001273 3.A.2.Na.4.b
Association CEGL001278 Creosotebush / Yucca species Shrubland CEGL001278 3.A.2.Na.4.b
Association CEGL002717 Creosotebush - Blackbrush Shrubland CEGL002717 3.A.2.Na.4.b
Association CEGL002955 Creosotebush - Brittlebush Shrubland CEGL002955 3.A.2.Na.4.b
Association CEGL004452 Ocotillo Shrubland CEGL004452 3.A.2.Na.4.b
Association CEGL005081 Sticky Brittlebush Shrubland CEGL005081 3.A.2.Na.4.b
Association CEGL005118 Ocotillo / (Brittlebush, Sticky Brittlebush) Shrubland CEGL005118 3.A.2.Na.4.b
Association CEGL005138 Creosotebush - Brittlebush - Ocotillo Shrubland CEGL005138 3.A.2.Na.4.b
Association CEGL005145 Creosotebush Shrubland CEGL005145 3.A.2.Na.4.b
Association CEGL005766 Creosotebush - Brittlebush - Burrobush Desert Shrubland CEGL005766 3.A.2.Na.4.b
Association CEGL005767 Creosotebush - Brittlebush - Bush Arrowleaf Desert Shrubland CEGL005767 3.A.2.Na.4.b
Association CEGL005768 Creosotebush / Big Galleta Desert Shrubland CEGL005768 3.A.2.Na.4.b
Concept Lineage: This alliance includes several old alliances such as III.A.5.N.b. Larrea tridentata - Encelia farinosa Shrubland Alliance (A.2533); III.A.5.N.a. Larrea tridentata Shrubland Alliance (A.851), in part; III.A.5.N.a. Fouquieria splendens Shrubland Alliance (A.863), in part; III.A.5.N.b. Encelia (farinosa, resinifera) Shrubland Alliance (A.867), in part; and III.A.5.N.b. Eriogonum fasciculatum Shrubland Alliance (A.868), in part.

Predecessors: No Data Available

Obsolete Names: No Data Available

Obsolete Parents: No Data Available
Synonomy: >< Fouquieria splendens Shrubland Alliance (Evens et al. 2014)
> Larrea tridentata - Encelia farinosa (Creosote bush - brittle bush scrub) Alliance (Sawyer et al. 2009) [33.027.00]
> Larrea tridentata - Encelia farinosa Shrubland Alliance (Evens et al. 2012)
> Larrea tridentata-Encelia farinosa Shrubland Alliance (Evens et al. 2014)
>< Enriched Desert Scrub (Cheatham and Haller 1975)
Concept Author(s): K.A. Schulz, in Faber-Langendoen et al. (2013)

Author of Description: K.A. Schulz

Acknowledgements: We have incorporated significant descriptive information previously compiled by M.S. Reid.

Version Date: 01-20-17
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