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F039 Tropical Thorn Woodland Formation
Type Concept Sentence: Tropical Thorn Woodland includes warm semi-arid or arid deciduous woodlands and low forests with xeromorphic adaptations found in Tropical, Mediterranean and Temperate xeric and desertic bioclimates around the globe, uncommon near the equator to increasingly common between 15° and 35°N and S latitude.
Common (Translated Scientific) Name: Tropical Thorn Woodland Formation
Colloquial Name: Tropical Thorn Woodland
Hierarchy Level: Formation
Type Concept: Tropical Thorn Woodland includes warm semi-arid or arid deciduous woodlands and low forests with several xeromorphic adaptations such as microphyllous and/or resinous leaves, thorns, brachyblasts, pachycaulal treelets and diverse shrubby and arborescent Cactaceae. The woodland canopy varies from open to closed. The low structural layer of this woodland/forest is frequently largely dominated by dense colonies of thorny terrestrial bromeliads. In the open ground, and intermixed with the woodlands, occur stands of ephemeral herbaceous vegetation that develop in the rainy season. The drought season is always strong, with 6-10 climatic and ecologically dry months per year.
Diagnostic Characteristics: Tropical Thorn Woodland includes warm semi-arid or arid deciduous woodlands and low forests with several xeromorphic adaptations such as microphyllous and/or resinous leaves, thorns, brachyblasts, pachycaulal treelets and diverse shrubby and arborescent Cactaceae.
Rationale for Nominal Species or Physiognomic Features: No Data Available
Classification Comments: Many authors include Tropical Thorn Woodland as part of a broadly defined "Tropical Dry Forest & Woodland" or "seasonally dry tropical forest" (SDTF). For example, Pennington et al. (2006) use a wide interpretation of SDTF in the Neotropics, including formations as diverse as tall forest on moister sites to cactus scrub on the driest, but they exclude the Chaco of Argentina, Paraguay, and Bolivia because it receives frost. See also Oliveira-Filho et al. (2006) who include caatinga and carrascos within their broad definition of SDTF, but exclude cerrados and chaco. Here, we create a separate formation for Tropical Thorn Woodlands in which we unite the xeromorphic parts of the caatinga, carrascos, cerrados, and chaco, separate from a more narrowly defined 1.A.1. ~Tropical Dry Forest & Woodland Formation (F003)$$ that lacks xeromorphic growth forms.
Distribution of this type needs review. It may be most common in tropical climates, but may extend into warm-temperate regions, such as northern Mexico and southwestern United States. By our definition, a certain amount of frost can also occur.
Distribution of this type needs review. It may be most common in tropical climates, but may extend into warm-temperate regions, such as northern Mexico and southwestern United States. By our definition, a certain amount of frost can also occur.
Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: The canopy is 8 to 15 m tall, open to dense, and dominated by low deciduous trees, arboreal cacti and high shrubs with xeromorphic adaptations. Very characteristic large colonies of thorny terrestrial clumping bromeliads, diverse thorn microphyllous scrubs and xeromorphic herbs and vines are frequently found in the understory.
Floristics: No Data Available
Dynamics: No Data Available
Environmental Description: Climate: Tropical Thorn Woodland occurs in Tropical, Mediterranean and Temperate xeric and desertic bioclimate categories of the global bioclimatic classification of Rivas-Martínez and Rivas-Saenz (1996-2009), with dry, semi-arid and arid ombrotypes. Soil/substrate/hydrology: The soils are well- to somewhat well-drained, non-floodable and xeric, frequently on old alluvial plains and glacis.
Geographic Range: The largest area of this formation in the Neotropics is the Gran Chaco ecoregion in southern Bolivia, northern Argentina, and northwestern Paraguay. Other important areas include the dry Inter-Andean Valley ecoregion of the southern Bolivian Andes and northwestern Argentina and the Caatinga ecoregion in Brazil and the Colombian-Venezuelan Guajira. Minor areas also occur in southwestern Pacific coastal Ecuador and adjacent northwestern Perú (Tumbesian ecoregion). In extratropical areas of South America, this formation occurs in semi-deserts and deserts of central Chile and in central-west Argentina (xeric Patagonia, Argentinian Monte). Elsewhere these woodlands may be expected in Africa and parts of the Indo-Malaysian tropics.
Nations: AR,BO,BR,CL,CO,EC,MX,PE,PY,US?,VE
States/Provinces: No Data Available
Plot Analysis Summary:
http://vegbank.org/natureserve/ELEMENT_GLOBAL.2.860265
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.1 Tropical Thorn Woodland Formation | F039 | 3.A.1 |
Concept Lineage: No Data Available
Predecessors: No Data Available
Obsolete Names: No Data Available
Obsolete Parents: No Data Available
Synonomy: = Tropical thorn scrub or thornwood: biome-type 9 (Whittaker 1975)
- 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.
- Navarro, G. 2004. Mapa de Vegetación del Parque Nacional y Area Natural de Manejo Integrado "KAA-IYA" del Gran Chaco. CABI- WCS- USAID. Editorial FAN. Santa Cruz de la Sierra. 42 pp. + 1 mapa.
- Navarro, G., J. A. Molina, and L. Perez de Molas. 2006. Classification of the forests of the northern Paraguayan Chaco. Phytocoenologia 36(4).
- Navarro, G., and M. Maldonado. 2002. Geografía Ecológica de Bolivia: Vegetación y Ambientes Acuáticos. Editorial Centro de Ecología Simón I. Patiño. Cochabamba, Bolivia. 719 pp.
- Oliveira-Filho, A. T., J. A. Jarenkow, and M. G. Nogueira Rodal. 2006. Floristic relationships of seasonally dry forests of eastern South America based on tree species distribution patterns. Pages 159-192 in: R. T. Pennington, G. P. Lewis, and J. A. Ratter, editors. Neotropical savannas and seasonally dry forests: Plant diversity, biogeography and conservation. CRC Press, Boca Raton, FL.
- Pennington, R. T., G. P. Lewis, and J. A. Ratter. 2006b. An overview of the plant diversity, biogeography and conservation of neotropical savannas and seasonally dry forests. Pages 1-29 in: R. T. Pennington, G. P. Lewis, and J. A. Ratter, editors. Neotropical savannas and seasonally dry forests: Plant diversity, biogeography and conservation. CRC Press, Boca Raton, FL.
- Rivas-Martínez, S., and S. Rivas-Saenz. 1996-2009. Worldwide Bioclimatic Classification System. Phytosociological Research Center, Spain. [http://www.globalbioclimatics.org]
- Whittaker, R. H. 1975. Communities and ecosystems. Second edition. Macmillan Publishing Co., New York. 387 pp.