Invalid Unit Specified
F015 Warm Desert & Semi-Desert Scrub & Grassland Formation

The U.S. National
Vegetation Classification
Type Concept Sentence: Warm Desert & Semi-Desert Scrub & Grassland occurs in dry warm-temperate, subtropical and tropical climates, is uncommon near the equator to increasingly common between 15° and 35°N and S latitude.
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Common (Translated Scientific) Name: Warm Desert & Semi-Desert Scrub & Grassland Formation
Colloquial Name: Warm Desert & Semi-Desert Scrub & Grassland
Hierarchy Level: Formation
Type Concept: Warm Desert & Semi-Desert Scrub & Grassland occurs in dry warm-temperate, subtropical and tropical climates. Vegetation is dominated by xeromorphic growth forms, and varies from shrub-scrub to complexes of succulents, thornscrub, and microphyllous-leaved subshrubs, often <2 m tall, though scattered tall succulents may occur. Ephemeral (therophytic) herbaceous growth forms may also be present. Desert grasslands often occur in transitional zones, typically containing a sparse layer of xeromorphic shrubs and an open ground layer. Included are very open deserts where vegetation is very sparse, and where the ground layer is sandy, stony desert pavements, salt crust (bare rock, often with nonvascular mats is placed in lithomorphic vegetation). Australian semi-deserts are most unlike other semi-deserts; succulents are lacking and spiny tussock grasses (spinifex, Triodia) are major plants.
Diagnostic Characteristics: Vegetation is dominated by xeromorphic growth forms, and varies from open shrub-scrub to complexes of succulents, thornscrub, and microphyllous-leaved subshrubs, often <2 m tall, though scattered tall succulents may occur. Ephemeral (therophytic) herbaceous growth forms may also be present.
Rationale for Nominal Species or Physiognomic Features:
Classification Comments: No Data Available
Similar NVC Types:
F039 Tropical Thorn Woodland, note:
Physiognomy and Structure: Vegetation is dominated by xeromorphic growth forms, and varies from open shrub-scrub to complexes of succulents, thornscrub, and microphyllous-leaved subshrubs, often <2 m tall, though scattered tall succulents may occur. Ephemeral (therophytic) herbaceous growth forms may also be present. Desert grasslands often occur in transitional zones, typically containing a sparse layer of xeromorphic shrubs and an open ground layer. Included are very open deserts where vegetation is very sparse, and where the ground layer is sandy, stony desert pavements, salt crust (bare rock, often with nonvascular mats is placed in lithomorphic vegetation). Australian semi-deserts, having evolved in long isolation, are most unlike other semi-deserts on other continents; succulents are lacking and spiny tussock grasses (spinifex, Triodia) are major plants (Whittaker 1975).
Floristics:
Dynamics: No Data Available
Environmental Description: Climate: Warm Desert & Semi-Desert Scrub & Grassland occurs in dry warm-temperate, subtropical and tropical climates. Mean summer temperatures are 29.5 to 35°C, and mean winter temperatures 7° to 15.5°C. Annual precipitation is 0 to 25 cm as rain only (Quinn 2009). Soil/substrate/hydrology: Calcification, salinization, Aridisol, azonal, salt pans, rocky, sandy, with little humus (Quinn 2009).
Geographic Range: Warm Desert & Semi-Desert Scrub & Grassland occurs in dry warm-temperate, subtropical and tropical climates, uncommon near the equator to increasingly common between 15° and 35°N and S latitude. In North America, it is found in the Mojave, Sonoran, and Chihuahuan regions, and southward into México; in South America, from Argentina and Chile to Bolivia and Peru, then scattered parts of Venezuela and Colombia; great areas of the semi-desert surround the Sahara in northern Africa and extend through the Arabian Peninsula to Iran and the Thar Deseret of India. More limited areas with distinctive semi-desert occur in parts of the arid areas in East Africa (Somali-Chalbi) and Southwest Africa (Kalahari and Karoo). Australian semi-deserts are a quite distinctive form (Whittaker 1975).
Nations: AR, AU, BO, CO, EC, MX, PE, PY, US, VE
States/Provinces:
Omernik Ecoregions:
Plot Analysis Summary:
Confidence Level: High
Confidence Level Comments:
Grank: GNR
Greasons:
Concept Lineage:
Predecessors:
Obsolete Names:
Obsolete Parents:
Synonomy: = Warm Deserts (Quinn 2009)
= Warm semidesert scrub: biome-type 17 (Whittaker 1975)
Concept Author(s): Hierarchy Revisions Working Group, Federal Geographic Data Committee (Faber-Langendoen et al. 2014)
Author of Description: D. Faber-Langendoen and G. Navarro
Acknowledgements:
Version Date: 17Oct2014
References:
  • Faber-Langendoen, D., T. Keeler-Wolf, D. Meidinger, C. Josse, A. Weakley, D. Tart, G. Navarro, B. Hoagland, S. Ponomarenko, J.-P. Saucier, G. Fults, and E. Helmer. 2015c. Classification and description of world formation types. General Technical Report RMRS-GTR-000. USDA Forest Service, Rocky Mountain Research Station, Fort Collins, CO.
  • Quinn, J. A. 2009. Desert biomes. Greenwood Press, Westport, CT.
  • Whittaker, R. H. 1975. Communities and ecosystems. Second edition. Macmillan Publishing Co., New York. 387 pp.