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The Altoandina comprises the upper part of the southern Andes, from latitude c. 25°S to the tip of the continent in Tierra del Fuego (55°S) (see Map 36). This southern part of the Andes includes the highest mountain in the western hemisphere (Aconcagua - 6959 m). The lower limit of the Altoandina vegetation descends from c. 4400 m in the north to c. 500 m in the extreme south; in the south it occurs as ecological islands surrounded by forest. The climate is cold and dry, though more humid southward. The scarce precipitation sometimes falls as snow. Winds are strong.
The most important vegetation types are grass-steppe, chamaephyte-steppe and shrub-steppe. Apart from grasses, the grass-steppe sometimes includes mat-forming species, such as Adesmia, Azorella, Junellia, Mulinum, Senecio and Verbena (Hunziker 1952; Ward and Dimitri 1966). Chamaephyte-steppe is generally found on loose soil at high elevations; common dwarf plants include Senecio spp. and cushion-forming Oxalis compacta, Pycnophyllum molle, Valeriana spp. and Werneria spp. Lichen semi-desert occurs on the most humid slopes, up to 5900 m. Bogs with Cyperaceae, Juncaceae and Gramineae are found in wet places.
The puna, Altoandina and Patagonia constitute the Andino-Patagonian floristic Dominion (Cabrera 1976; Cabrera and Willink 1973). The flora includes neotropical, holarctic and (especially to the south) antarctic elements (Cabrera 1976). Well-represented families include Gramineae (Calamagrostis, Festuca, Poa, Stipa), Leguminosae (Adesmia, Astragalus) and Compositae (Chuquiraga, Mutisia, Senecio). There are no endemic families; endemic genera include Barneoudia, Hexaptera, Nototriche, Pycnophyllum and Werneria.
Numerous species are used as forage, fuel or medicinal (Ruthsatz 1974).
Social and environmental values, Threats, Conservation
Social and environmental values
Map 36. Centres of Plant Diversity and Endemism: South America
Cabrera, A.L. (1976). Regiones fitogeográficas argentinas. In Parodi, L.R. (ed.), Enciclopedia argentina de agricultura y jardinería, 2nd edition. Vol. 2(1). Editorial Acmé, Buenos Aires. Pp. 1-85.
Cabrera, A.L. and Willink, A. (1973). Biogeografía de América Latina. Organización de los Estados Americanos (OEA), Serie de Biología, Monogr. No. 13, Washington, D.C. 117 pp.
Hunziker, J.H. (1952). Las comunidades vegetales de la Cordillera de La Rioja. Rev. Invest. Agric. 6: 167-196.
Ruthsatz, B. (1974). Los arbustos de las estepas andinas del noroeste argentino y su uso actual. Bol. Soc. Argent. Bot. 16:27-45.
Ward, R.T. and Dimitri. M.J. (1966). Alpine tundra on Mt. Catedral in
the southern Andes. New Zealand J. Bot. 4: 42-56.
Note: Information here is summarized from the South America overview found in the published work..
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