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A3152 Flourensia cernua Lowland Basin Desert Scrub Alliance
Type Concept Sentence: This alliance includes extensive open-canopied shrublands of lowland, often somewhat saline basins in the Chihuahuan Desert, and is characterize by the dominance of Flourensia cernua with low cover of common associated species Atriplex canescens, Larrea tridentata, Lycium berlandieri, Cylindropuntia leptocaulis, and Prosopis glandulosa. The understory ranges from barren or sparse to abundant graminoid cover dominated by Sporobolus airoides, Pleuraphis mutica, and intermittent patches of Scleropogon brevifolius.
Common (Translated Scientific) Name: American Tarwort Lowland Basin Desert Scrub Alliance
Colloquial Name: American Tarwort Lowland Basin Scrub
Hierarchy Level: Alliance
Type Concept: This alliance includes extensive open-canopied shrublands of lowland, often somewhat saline basins in the Chihuahuan Desert, and is characterize by the dominance of Flourensia cernua with low cover of common associated species Atriplex canescens, Larrea tridentata, Lycium berlandieri, Cylindropuntia leptocaulis, and Prosopis glandulosa. The understory ranges from barren or sparse to abundant graminoid cover dominated by Sporobolus airoides, Pleuraphis mutica, and intermittent patches of Scleropogon brevifolius. Stands often occur on alluvial flats and around playas, as well as in floodplains. Substrates are generally fine-textured, often saline soils.
Diagnostic Characteristics: These open-canopied shrublands are dominated by Flourensia cernua usually with the presence of saline or alkaline indicator species in the herbaceous layer such as Sporobolus airoides, Pleuraphis mutica, or Distichlis spicata. Flourensia cernua is a Chihuahua Desert indicator species, but others are likely present, such as Acourtia nana, Euphorbia dentata, or Hoffmannseggia glauca.
Rationale for Nominal Species or Physiognomic Features: No Data Available
Classification Comments: Natural Heritage of New Mexico has additional associations that need to be reviewed for possible inclusion in the USNVC and this alliance.
Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: Vegetation included in this alliance has sparse to moderately dense cover of broad-leaved and microphyllous, evergreen shrub less the 1 m tall. The sparse to moderately dense herbaceous layer is dominated by perennial graminoids. Annual grasses and forbs are present seasonally.
Floristics: This Chihuahuan Desert alliance is dominated by Flourensia cernua with low cover of common associated species Atriplex canescens, Larrea tridentata, Lycium berlandieri, Cylindropuntia leptocaulis (= Opuntia leptocaulis), and Prosopis glandulosa. The understory ranges from barren or sparse to abundant graminoid cover dominated by Sporobolus airoides, Pleuraphis mutica, and intermittent patches of Scleropogon brevifolius. Other species in the herbaceous layer include Achnatherum eminens (= Stipa eminens), Dasyochloa pulchella (= Erioneuron pulchellum), Muhlenbergia porteri, Pleuraphis mutica (= Hilaria mutica), and Sporobolus airoides. Common forbs include Acourtia nana, Croton texensis, Dyssodia spp., Eriogonum wrightii, Euphorbia dentata, Hoffmannseggia glauca, Lepidium montanum, Machaeranthera pinnatifida, Solanum elaeagnifolium, Phemeranthus aurantiacus (= Talinum aurantiacum), and Zinnia spp. Johnson (1961c) reported cover values for lowland stands in New Mexico where Flourensia cernua, Larrea tridentata, Dasyochloa pulchella, total perennial cover and total annual cover that were 19%, 5%, 8%, 32%, and 10%, respectively.
Dynamics: Flourensia cernua has increased in abundance in this century (Muldavin et al. 1998c). Livestock grazing favors Flourensia cernua over grasses because the shrub is unpalatable to livestock and relatively shallow-rooted, and therefore competes strongly with grasses for soil moisture (Muldavin et al. 1998c). Severe droughts and overgrazing early in this century have likely contributed to these changes in the vegetation. Buffington and Herbel (1965) report that Larrea tridentata has displaced many stands of Flourensia cernua and cite that it may be because Larrea tridentata only competes with grasses during the shrub''s seedling stage. Muldavin (1998) states that stands with no graminoid layer are unlikely to develop one, but stands with a graminoid layer are likely to maintain it if not overgrazed. Impermeable caliche and argillic horizons are not uncommon on these sites. These layers restrict deep percolation of soil-water and may favor the shallower root grasses and shrubs like Flourensia cernua over more deeply rooted shrubs like Larrea tridentata and Prosopis spp. (McAuliffe 1995).
Environmental Description: This alliance includes extensive open-canopied shrublands of lowland, often somewhat saline basins in the Chihuahuan Desert. Stands often occur on alluvial flats and around playas, as well as in floodplains. This is a major alliance of the Oscura and San Andres mountains in shallow swales in basins and shallow drainages of both upper and lower piedmont slopes at elevations of 1160 to 1650 m, and in the Jornada Del Muerto and Tularosa basins where it occurs in swales or broad drainages along lower alluvial plains and basin bottoms, at elevations of 1160 to 2040 m (Muldavin et al. 2000b). Generally, slopes are flat to very gentle. Soils are derived from alluvial deposits from the surrounding mountains. Soils are heavy clay loams, silty loams or silty clays typical of depositional swale sites. Ground surfaces are characterized by patches of bare soil and scattered litter with coarse materials absent from soil surfaces (Muldavin et al. 2000b).
Geographic Range: This alliance occurs in saline basins in the Chihuahuan Desert in southern New Mexico and southeastern Arizona, and likely in the Trans-Pecos of Texas and the Mexican states of Coahuila and Chihuahua. Stands often occur around playas and on alluvial flats, as well as in floodplains along the Rio Grande and Pecos River.
Nations: MX,US
States/Provinces: AZ, MXCHH, MXCOA, NM, TX
Plot Analysis Summary:
http://vegbank.org/natureserve/ELEMENT_GLOBAL.2.899277
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.b Fourwing Saltbush - American Tarwort Lowland Basin Scrub Group | G299 | 3.A.2.Na.2.b |
| Alliance | A3152 American Tarwort Lowland Basin Desert Scrub Alliance | A3152 | 3.A.2.Na.2.b |
| Association | CEGL001337 American Tarwort / Alkali Sacaton Shrubland | CEGL001337 | 3.A.2.Na.2.b |
| Association | CEGL001541 American Tarwort / Tobosa Grass Shrubland | CEGL001541 | 3.A.2.Na.2.b |
Concept Lineage: Old Alliance III.A.5.N.a. Flourensia cernua Shrubland Alliance (A.861), in part - two lowland associations.
Predecessors: No Data Available
Obsolete Names: No Data Available
Obsolete Parents: No Data Available
Synonomy: < Flourensia cernua Association (153.214) (Brown 1982a) [included within the Chihuahuan Desertscrub Creosotebush-Tarbush Series.]
- Brown, D. E., editor. 1982a. Biotic communities of the American Southwest-United States and Mexico. Desert Plants Special Issue 4(1-4):1-342.
- Buffington, L. C., and C. H. Herbel. 1965. Vegetational changes on a semidesert grassland range from 1858 to 1963. Ecological Monographs 35(2):139-164.
- Dick-Peddie, W. A. 1993. New Mexico vegetation: Past, present, and future. University of New Mexico Press, Albuquerque. 244 pp.
- Faber-Langendoen, D., J. Drake, M. Hall, G. Kittel, S. Menard, C. Nordman, M. Pyne, M. Reid, M. Russo, K. Schulz, L. Sneddon, K. Snow, and J. Teague. 2013-2019b. Screening alliances for induction into the U.S. National Vegetation Classification: Part 1 - Alliance concept review. NatureServe, Arlington, VA.
- Johnson, D. E. 1961c. Edaphic factors affecting the distribution of creosotebush (Larrea tridentata (DC.) Cov.) in desert grassland sites of southeastern Arizona. Unpublished thesis, University of Arizona, Tucson. 58 pp.
- Leopold, B. D., and P. R. Krausman. 1988. Plant associations of the lower desert shrubland in Big Bend National Park, Texas. Contributed paper second symposium on the Resources of the Chihuahuan Desert. Chihuahuan Desert Research Institute, Alpine, TX. 47 pp.
- McAuliffe, J. R. 1995. Landscape evolution, soil formation, and Arizona''s desert grasslands. Pages 100-129 in: M. P. McClaran and T. R. Van Devender, editors. The Desert Grassland. University of Arizona Press, Tucson.
- McMahan, C. A., R. G. Frye, and K. L. Brown. 1984. The vegetation types of Texas including cropland. Texas Parks and Wildlife Department, Austin. 40 pp. plus map.
- Muldavin, E., P. Mehlhop, and E. DeBruin. 1994a. A survey of sensitive species and vegetation communities in the Organ Mountains of Fort Bliss. Volume III: Vegetation communities. Report prepared for Fort Bliss, Texas, by New Mexico Natural Heritage Program, Albuquerque.
- Muldavin, E., Y. Chauvin, and G. Harper. 2000b. The vegetation of White Sands Missile Range, New Mexico: Volume I. Handbook of vegetation communities. Final report to Environmental Directorate, White Sands Missile Range. New Mexico Natural Heritage Program, University of New Mexico, Albuquerque. 195 pp. plus appendices
- Muldavin, E., and P. Mehlhop. 1992. A preliminary classification and test vegetation map for White Sands Missile Range and San Andreas National Wildlife Refuge, New Mexico. University of New Mexico, New Mexico Natural Heritage Program.
- Muldavin, E., et al. 1998c. Plant community inventory for Fort Bliss. Unpublished report in preparation by the New Mexico Natural Heritage Program, Albuquerque, NM.
- Stein, R. A., and J. A. Ludwig. 1979. Vegetation and soil patterns on a Chihuahuan Desert bajada. The American Midland Naturalist 101:28-37.