Invalid Unit Specified
S06 Warm Desert & Semi-Desert Woodland, Scrub & Grassland Subclass

The U.S. National
Vegetation Classification
Type Concept Sentence: Warm Desert & Semi-Desert Woodland, 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.
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Common (Translated Scientific) Name: Warm Desert & Semi-Desert Woodland, Scrub & Grassland Subclass
Colloquial Name: Warm Desert & Semi-Desert Woodland, Scrub & Grassland
Hierarchy Level: Subclass
Type Concept: Warm Desert & Semi-Desert Woodland, Scrub & Grassland occurs in dry warm-temperate, subtropical and tropical climates. Vegetation is dominated by xeromorphic growth forms, and varies from open to closed woodlands, 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 within semi-desert woodlands. Desert grasslands often occur in transitional zones, typically containing a sparse layer of xeromorphic shrubs and 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).
Diagnostic Characteristics: Vegetation is dominated by xeromorphic growth forms, and varies from open to closed woodlands, 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: This subclass includes the low desert-like tropical thornwoods, which can form a transition to 1.A.1. Tropical Dry Forest & Woodland Formation (F003). In the Neotropics, Brazilian caatinga includes both Tropical Dry Forest & Woodlands and extensive Tropical Thorn Woodland and scrub. This subclass also occurs in the Neotropics in the Guajira (Colombia, Venezuela), Gran Chaco (Bolivia, Argentina, Paraguay), Low Dry Inter-Andean Valleys (Bolivia, Argentina) and Pacific semi-deserts of west-southern Ecuador and northwestern Perú (Tumbes).
Similar NVC Types:
S17 Tropical Forest & Woodland, note: 1.A. ~Tropical Forest & Woodland Subclass (S17)$$ in drier climates may have small-leaved sclerophyllous evergreen trees or deciduous trees that can be similar to trees found in thorn woodland in warm deserts. Thorn woodlands are sometimes included as part of Tropical Forest.
Physiognomy and Structure: Vegetation is dominated by xeromorphic growth forms, and varies from open to closed woodlands, 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 within semi-desert woodlands. Desert grasslands often occur in transitional zones, typically containing a sparse layer of xeromorphic shrubs and 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 (Whittaker 1975).
Floristics:
Dynamics: No Data Available
Environmental Description: Climate: Warm semi-desert woodlands, scrub and grasslands occur in dry warm-temperate, subtropical and tropical climates.
Geographic Range: Warm Desert & Semi-Desert Woodland, 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.
Nations: US
States/Provinces:
Omernik Ecoregions:
Plot Analysis Summary:
Confidence Level: High
Confidence Level Comments:
Grank: GNR
Greasons:
Name:Database Code:Classification Code:
Class 3 Desert & Semi-Desert C03 3
Subclass 3.A Warm Desert & Semi-Desert Woodland, Scrub & Grassland S06 3.A
Formation 3.A.2 Warm Desert & Semi-Desert Scrub & Grassland F015 3.A.2
Formation 3.A.1 Tropical Thorn Woodland F039 3.A.1
Concept Lineage:
Predecessors:
Obsolete Names:
Obsolete Parents:
Synonomy: > Warm Deserts (Quinn 2009) [The author does not include thorn woodlands.]
= Warm semidesert scrub: biome-type 17 (Whittaker 1975) [The author does not include thorn woodlands.]
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.