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G295 Larrea tridentata - Ambrosia dumosa - Encelia farinosa Desert Scrub Group
Type Concept Sentence: This Mojave-Sonoran desert scrub group is characterized by Larrea tridentata and Ambrosia dumosa along with several other shrubs, and is found in the warm southwestern deserts of the U.S. and northern Mexico.
Common (Translated Scientific) Name: Creosotebush - Burrobush - Brittlebush Desert Scrub Group
Colloquial Name: Mojave-Sonoran Bajada & Valley Desert Scrub
Hierarchy Level: Group
Type Concept: This desert scrub vegetation group forms the vegetation matrix in broad valleys, lower bajadas, plains and low hills in the Mojave, western Sonoran and Lower Colorado deserts where winter (cool-season) precipitation prevails. This desert scrub is characterized by a sparse to moderately dense layer (2-50% cover) of xeromorphic, microphyllous and broad-leaved shrubs. Larrea tridentata and Ambrosia dumosa typically dominate and are diagnostic of this group, but many different shrubs, dwarf-shrubs, and cacti may codominate or form typically sparse understory layers. Associated species may include Encelia farinosa, Ephedra aspera, Ephedra nevadensis, Fouquieria splendens, Lycium andersonii, Opuntia basilaris, and Cylindropuntia bigelovii. The herbaceous layer is typically sparse, but may be seasonally abundant with ephemerals. Herbaceous species such as Aristida spp., Chamaesyce spp., Cryptantha spp., Dasyochloa pulchella, Eriogonum inflatum, Nama spp., and Phacelia spp. are common. On sandy sites, perennial grass Pleuraphis rigida may be abundant with Ambrosia dumosa. Stands can often appear as very open sparse vegetation, with the mostly barren ground surface being the predominant feature.
Diagnostic Characteristics: This desert scrub vegetation group is characterized by a sparse to moderately dense layer (2-50% cover) of xeromorphic, microphyllous and broad-leaved shrubs. Diagnostic species Larrea tridentata and Ambrosia dumosa typically dominate, but many different shrubs, dwarf-shrubs, and cacti may codominate or form typically sparse understory layers. Associated species may include Encelia farinosa, Ephedra nevadensis, Fouquieria splendens, Lycium andersonii, Opuntia basilaris, and Cylindropuntia bigelovii. Cylindropuntia bigelovii, Encelia farinosa, and Fouquieria splendens can dominate scrub locally The herbaceous layer is typically sparse, but may be seasonally abundant with ephemerals.
Rationale for Nominal Species or Physiognomic Features: No Data Available
Classification Comments: This desert scrub vegetation group forms the vegetation matrix in broad valleys, lower bajadas, plains and low hills in the Mojave, western Sonoran and Lower Colorado deserts where winter (cool-season) precipitation prevails. This desert scrub is characterized by a sparse to moderately dense layer (2-50% cover) of xeromorphic, microphyllous and broad-leaved shrubs.
Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: This desert scrub vegetation group is characterized by a sparse to moderately dense layer (2-50% cover) of xeromorphic, microphyllous and broad-leaved shrubs less than 2 m tall. Stands can often appear as very open sparse vegetation, with the mostly barren ground surface being the predominant feature.
Floristics: This desert scrub vegetation group forms the vegetation matrix in broad desert valleys, lower bajadas, desert plains and low hills. It is characterized by a sparse to moderately dense layer (2-50% cover) of xeromorphic, microphyllous and broad-leaved shrubs. Diagnostic species Larrea tridentata and Ambrosia dumosa are typically dominant, but many different shrubs, dwarf-shrubs, and cacti may codominate or form typically sparse understory layers. Associated species may include Echinocactus polycephalus, Encelia farinosa, Ephedra funerea, Ephedra aspera (= Ephedra fasciculata), Ephedra nevadensis, Fouquieria splendens, Grayia spinosa, Krameria grayi, Krameria erecta, Lycium andersonii, Opuntia basilaris, Cylindropuntia bigelovii (= Opuntia bigelovii), Psorothamnus arborescens, Psorothamnus fremontii, Salazaria mexicana, and Senna armata. Cylindropuntia bigelovii, Encelia farinosa, and Fouquieria splendens can dominate scrub locally. The herbaceous layer is typically sparse, but may be seasonally abundant with ephemerals. Herbaceous species such as Aristida spp., Chamaesyce spp., Cryptantha spp., Dasyochloa pulchella, Eriogonum inflatum, Nama spp., and Phacelia spp. are common. On sandy sites, perennial grass Pleuraphis rigida may be abundant with Ambrosia dumosa. This group can often appear as very open sparse vegetation, with the mostly barren ground surface being the predominant feature.
Dynamics: No Data Available
Environmental Description: This widespread desert scrub vegetation group forms the vegetation matrix in broad valleys, lower bajadas, plains and low hills in the Mojave, western Sonoran and Lower Colorado deserts. Elevation ranges from -75 to 1200 m. Stands occur on alluvial fans, bajadas, upland slopes and minor washes. Sites are gentle to moderately sloping. Substrates are typically well-drained, sandy soils derived from colluvium or alluvium, and are often calcareous with a caliche hardpan and/or a pavement surface. Precipitation is markedly unimodal with most falling in the winter months associated with winter storm tracks reaching the desert from the Pacific Ocean. Summer thunder showers associated with monsoonal storms from the south are irregular and less important than those in ~Sonoran Paloverde - Mixed Cacti Desert Scrub Group (G293)$$. The lack of arborescent cacti, and microphyllous tall shrubs and trees in uplands are one indicator of unreliable summer precipitation.
Geographic Range: This desert scrub vegetation group occupies broad valleys, lower bajadas, plains and low hills in the Mojave, western Sonoran and Lower Colorado deserts.
Nations: MX,US
States/Provinces: AZ, CA, MXBCN, MXSON, NM, NV, UT
Plot Analysis Summary:
http://vegbank.org/natureserve/ELEMENT_GLOBAL.2.833231
Confidence Level: Moderate
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 | A3146 Teddy-bear Cholla Cacti Scrub Alliance | A3146 | 3.A.2.Na.4.b |
| Alliance | A3277 Creosotebush - Burrobush Bajada & Valley Desert Scrub Alliance | A3277 | 3.A.2.Na.4.b |
| Alliance | A3278 Creosotebush - Ocotillo Upper Bajada & Rock Outcrop Desert Scrub Alliance | A3278 | 3.A.2.Na.4.b |
| Alliance | A3279 Burrobush Desert Dwarf Scrub Alliance | A3279 | 3.A.2.Na.4.b |
| Alliance | A4215 Brittlebush Desert Scrub Alliance | A4215 | 3.A.2.Na.4.b |
Concept Lineage: No Data Available
Predecessors: No Data Available
Obsolete Names: No Data Available
Obsolete Parents: No Data Available
Synonomy: < Creosote Bush Scrub (Holland and Keil 1995)
> Creosote Bush Scrub (211) (Shiflet 1994)
> Creosotebush - Bursage (506) (Shiflet 1994)
> Creosotebush-Big Galleta Scrub Natural Community (Hall et al. 2001)
> Creosotebush-Bursage Desert Scrub Natural Community (Hall et al. 2001)
= Lower Colorado River Valley: Larrea-Franseria region (Shreve and Wiggins 1964)
= Mohave Desertscrub, Creosotebush Series - 153.11 (Brown et al. 1979)
> Mohave Desertscrub, Creosotebush Series, Larrea divaricata-Ambrosia dumosa Association - 153.112 (Brown et al. 1979)
> Mohave Desertscrub, Creosotebush Series, Larrea divaricata Association - 153.111 (Brown et al. 1979)
> Creosote Bush Scrub (211) (Shiflet 1994)
> Creosotebush - Bursage (506) (Shiflet 1994)
> Creosotebush-Big Galleta Scrub Natural Community (Hall et al. 2001)
> Creosotebush-Bursage Desert Scrub Natural Community (Hall et al. 2001)
= Lower Colorado River Valley: Larrea-Franseria region (Shreve and Wiggins 1964)
= Mohave Desertscrub, Creosotebush Series - 153.11 (Brown et al. 1979)
> Mohave Desertscrub, Creosotebush Series, Larrea divaricata-Ambrosia dumosa Association - 153.112 (Brown et al. 1979)
> Mohave Desertscrub, Creosotebush Series, Larrea divaricata Association - 153.111 (Brown et al. 1979)
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