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A3189 Mortonia scabrella - Viguiera stenoloba - Bernardia obovata Chihuahuan Desert Scrub Alliance
Type Concept Sentence: This broadly defined foothill desert scrub alliance is found in Chihuahuan Desert and includes typically open scrub with a variety of dominant woody species, such as Mortonia scabrella, Dasylirion wheeleri, Leucophyllum minus, Viguiera stenoloba, and codominated by Bernardia obovata and Leucophyllum minus or Leucophyllum frutescens. Sites include rock outcrops and rocky foothills and mountains, often with substrates derived from limestone, igneous rock and possibly gypsum parent materials.
Common (Translated Scientific) Name: Rough Saddlebush - Resinbush - Desert Myrtle-croton Chihuahuan Desert Scrub Alliance
Colloquial Name: Chihuahuan Desert Mixed Scrub
Hierarchy Level: Alliance
Type Concept: This broadly defined foothill Chihuahuan Desert scrub alliance is found in southeastern Arizona, southern New Mexico, Trans-Pecos of western Texas, as well as on the Stockton Plateau. The typically open scrub canopy has a diversity of dominant woody species. Two associations have been included in this alliance. One is dominated by Mortonia scabrella with Dasylirion wheeleri and Quercus pungens, and the other is codominated by Viguiera stenoloba and Bernardia obovata with Chamaesyce sp. in the understory. However, Leucophyllum minus and other shrubs may also dominate stands as the concept of this alliance is broad. Other common shrubs may include Acacia greggii, Agave lechuguilla, Aloysia wrightii, Cercocarpus montanus var. paucidentatus, Dalea formosa, Dasylirion leiophyllum, Fouquieria splendens, Krameria erecta, Leucophyllum frutescens, Mimosa aculeaticarpa var. biuncifera, Nolina spp., Parthenium incanum, and Rhus virens var. choriophylla. Herbaceous species are often sparse, but may form an open to moderate layer composed of a variety of grasses such as Achnatherum eminens, Aristida purpurea var. nealleyi, Bouteloua curtipendula, Bouteloua eriopoda, Muhlenbergia emersleyi, and Tridens muticus. Frequent forbs include Bahia absinthifolia and Astrolepis sinuata. Climate is generally semi-arid with warm summers and cool winters. Approximately two-thirds of the 41 cm mean annual precipitation falls during the summer and early fall. The winter precipitation has high year-to-year variation. The cooler north and east aspects create relatively mesic sites necessary for the abundant growth of evergreen shrub species. Sites include rock outcrops and rocky foothills and mountains, often with substrates derived from limestone, igneous rock and possibly gypsum parent materials.
Diagnostic Characteristics: This broadly defined mixed Chihuahuan desert scrub alliance is dominated by Mortonia scabrella, Viguiera stenoloba, or Bernardia obovata. Other common shrubs may include Acacia greggii, Agave lechuguilla, Aloysia wrightii, Cercocarpus montanus var. paucidentatus, Dalea formosa, Dasylirion leiophyllum, Dasylirion wheeleri, Fouquieria splendens, Krameria erecta, Mimosa aculeaticarpa var. biuncifera, Nolina spp., Parthenium incanum, Quercus pungens, and Rhus virens var. choriophylla. If present, the herbaceous layer is usually sparse.
Rationale for Nominal Species or Physiognomic Features: No Data Available
Classification Comments: This broadly defined Chihuahuan Desert scrub alliance needs to be compared with succulent-dominated alliances.
Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: Vegetation in this alliance is dominated by xeromorphic broad-leaved and microphyllous evergreen shrubs (0.5-5 m tall).
Floristics: This broadly defined foothill Chihuahuan Desert scrub alliance has a typically open scrub canopy with high diversity of dominant woody species. Two associations have been included in this alliance. One is dominated by Mortonia scabrella (= Mortonia sempervirens ssp. scabrella) with Dasylirion wheeleri and Quercus pungens, and the other is codominated by Viguiera stenoloba and Bernardia obovata with Chamaesyce sp. in the understory. However, Leucophyllum minus and other shrubs may also dominate stands as the concept of this alliance is broad. Other common shrubs may include Acacia greggii, Agave lechuguilla, Aloysia wrightii, Cercocarpus montanus var. paucidentatus (= Cercocarpus breviflorus), Dalea formosa, Dasylirion leiophyllum, Fouquieria splendens, Krameria erecta (= Krameria glandulosa), Mimosa aculeaticarpa var. biuncifera, Nolina spp., Parthenium incanum, and Rhus virens var. choriophylla. Herbaceous species are often sparse, but may form an open to moderate layer composed of variety of grasses such as Achnatherum eminens (= Stipa eminens), Aristida purpurea var. nealleyi (= Aristida glauca), Bouteloua curtipendula, Bouteloua eriopoda, Muhlenbergia emersleyi, and Tridens muticus. Frequent forbs include Bahia absinthifolia and Astrolepis sinuata (= Notholaena sinuata).
Dynamics: No Data Available
Environmental Description: Climate is generally semi-arid with warm summers and cool winters. Approximately two-thirds of the 41 cm mean annual precipitation falls during the summer and early fall. The winter precipitation has high year-to-year variation. The cooler north and east aspects create relatively mesic sites necessary for the abundant growth of evergreen shrub species. Adjacent vegetation includes desert grasslands dominated by Elionurus barbiculmis, Heteropogon contortus, and Bouteloua spp. at lower elevations and other desert scrub stands dominated by Cercocarpus montanus, Rhus virens var. choriophylla, Acacia neovernicosa, or Parthenium incanum.
Geographic Range: This Chihuahuan Desert scrub alliance is found in southeastern Arizona, southern New Mexico, Trans-Pecos of western Texas, as well as on the Stockton Plateau, and possibly in portions of the Edwards Plateau. It is also found in New Mexico and the Mexican states of Chihuahua and Coahuila.
Nations: MX,US
States/Provinces: AZ, MXCHH, MXCOA, NM, TX
Plot Analysis Summary:
http://vegbank.org/natureserve/ELEMENT_GLOBAL.2.899313
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.2 Creosotebush - American Tarwort - Mesquite species Chihuahuan Desert Scrub Macrogroup | M086 | 3.A.2.Na.2 |
| Group | 3.A.2.Na.2.a Creosotebush - American Tarwort - Viscid Acacia Chihuahuan Mixed Desert Scrub Group | G288 | 3.A.2.Na.2.a |
| Alliance | A3189 Rough Saddlebush - Resinbush - Desert Myrtle-croton Chihuahuan Desert Scrub Alliance | A3189 | 3.A.2.Na.2.a |
| Association | CEGL001279 Rough Saddlebush / Common Sotol Shrubland | CEGL001279 | 3.A.2.Na.2.a |
| Association | CEGL004603 Resinbush - Desert Myrtle-croton / Sandmat species Shrubland | CEGL004603 | 3.A.2.Na.2.a |
Concept Lineage: Old Alliances do not crosswalk cleanly. III.A.5.N.a. Mortonia (sempervirens, utahensis) Shrubland Alliance (A.859), in part. One associations in this broadly defined alliance. III.A.5.N.a. Dasylirion leiophyllum - (Agave lechuguilla, Viguiera stenoloba) Shrubland Alliance (A.850), in part. One associations in this broadly defined alliance.
Predecessors: No Data Available
Obsolete Names: No Data Available
Obsolete Parents: No Data Available
Synonomy: No Data Available
- Diamond, D. D. 1993. Classification of the plant communities of Texas (series level). Unpublished document. Texas Natural Heritage Program, Austin. 25 pp.
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