Magellanes, Chile. Source: C. Cardenas/WWF

The Magellanic subpolar forests is an ecoregion dominated by trees of the genus Nothofagus; this geographic zone covers the western part of the southern end of South America as well as the extreme southern parts of Argentina and Chile, known by the region Tierra del Fuego. The ecoregion is colder and in parts drier than the Valdivian temperate forests, and in general is floristically poorer. The fauna is related to that of the bordering ecoregions, especially to that of the Valdivian temperate forests and the Patagonian steppe. Nevertheless, its varied and majestic landscapes that include high mountain peaks, enormous icefields, and innumerable fjords are inhabited by unique and endemic animal and plant species that are sometimes abundant within this ecoregion. 

Location and general description

The subpolar Nothofagus forests extend along the southern Andes Mountains and the Chilean archipelago from 47 ºS to the Cape Horn, including the regions of southern Aisen and Magallanes in Chile. In Argentina it only covers small surfaces of the western side of the province of Santa Cruz and the south of Tierra del Fuego from lake Buenos Aires to Staten Island. At this latitude three parallel regions, the Cordillera Patagónica Insular, the Cordillera Patagónica Occidental, and the Cordillera Patagónica Oriental form the Andes.

The northern end of the subpolar Nothofagus forests matches the limit of the Valdivian temperate forests and the eastern part of the Nothofagus forests borders the Patagonian steppe and the Patagonian grasslands. Towards the west the region is in contact with the cold southern Pacific Ocean, and on the high Andes vegetation floristically related to the south Andean steppe appears in parts as interrupted islands.

The relief of the northern portion has mountains of about 1500 metres (m), but several high peaks mark the limit between Chile and Argentina such as Mt. San Lorenzo (3706 m), Mt. Fitz Roy (3406 m) and Mt. Murallón (3600 m). Towards the west other very high mountains appear such as Mt. San Valentín (3910 m). Large lakes of glacial origin are also found in the limit of Argentina and Chile such as Lago Gral Carrera-Buenos Aires (the deepest and second largest lake in South America), L. Cochrane-Pueyrredón, L. O’Higgins-San Martín, L. Viedma and L. Argentino. The relief of the southern portion generally decreases to less than 1000 m, and in Tierra del Fuego the large L. Fagnano is found.

Permanent snow, ice caps and glaciers are present in the summits of many of the higher elevations. The effect of the cold temperatures, strong and permanent west winds and high precipitation on the windward side of the mountains of about 5000 millimetres (mm) per year has resulted in three enormous ice fields. These are the Northern Patagonian Ice Field (approx. 46º30’S to 47º30’S, 4200 square kilometres), the Southern Patagonian Ice Field (48º30’S to 51º30’S, 13000 km²), and the icefield of Cordillera Darwin in the southwest of Tierra del Fuego (54º30’S to 55ºS, 2300 km²). Most glaciers have receded in recent times, but during the ice ages of the Quaternary significant expansions of the glaciers in this ecoregion took place. At the end of the last glaciation, one of the more extensive areas in Patagonia had at least five glacial advances lasting between 70,000 and 11,000 years. At this time a continuous ice-sheet formed south of 42ºS from western Patagonia to the Pacific coast, but the north of the Southern Patagonian ice field rose only 300 to 700 m, suggesting that the ice cap left part of the relief uncovered.

Magellanic subpolar forested mountains. Background is the
Darwin icefield, one of the two permanent ice fields in
South America. Source: C.Michael Hogan

Soils of the ecoregion are varied, mostly depending on climate, but are generally acid due to high precipitation, low drainage, and slow decomposition of organic matter in relation to low temperatures. Towards the south and west podsols and acid brown forest soils develop in places with better drainage, and peat accumulates in less drained areas with bogs and tundra vegetation.

The climate of this area is wet and temperate-cold and very cold at high elevations. The effect of the cold northward Humboldt and Antarctica currents on the western and southern coasts makes the area colder than others at similar latitudes, with mean January (summer) temperatures lower than 10º C. The strong westerly winds blow all year round, producing high rainfall in the windward west side of the mountains and lower precipitation to the east, and no dry season. In general mean annual temperatures are between 6ºC in the north and 3ºC in the south, and mean annual precipitation varies, decreasing from west to east from approximately 4000 mm to 700 mm respectively. For example, mean annual precipitation in Bahía Félix at 53ºS 70ºW is 4845 mm, while in Ushuaia at 54ºS 68ºW it is 545 mm. Precipitation as snow can be abundant all the year round.

The vegetation shows principally two types of forest, mainly evergreen Nothofagus betuloides forests to the west and deciduous Nothofagus pumilio and Nothofagus antarctica forests towards the east that extend into Argentina. In Tierra del Fuego the evergreen forests are found to the south and the deciduous forests towards the interior. The deciduous forest is formed by pure Nothofagus pumilio at lower elevations, in different combinations with the more ecologically tolerant Nothofagus antarctica, which prevails in more arid situations or less drained soils. In frost pockets a heath dominated by Empetrum and Bolax is found. In humid or wet places of these forests especially rich raised bog-communities grow dominated by Sphagnum, Juncaceae, Cyperaceae and grasses.

The deciduous forest shows a transition to the evergreen forest to the west with mixed Nothofagus pumilio-Nothofagus betuloides forests. With approx. 1000-4000 mm precipitation N. betuloides becomes dominant, forming pure forests or mixed with Drymis winteri, Maytenus magellanica and Pilgerodendron uvifera. Inland shrubs of Fuchsia, Ribes, Hebe, Gaultheria and Empetrum accompany, while in coastal situations Hebe elliptica forms a dense scrub. In the north Nothofagus dombeyi and N. nitida are found up to 48ºS, and Podocarpus nubigena to 51ºS.

In the colder areas with high rainfall of the south western most parts of the ecoregion a characteristic vegetation specially termed Magellanic moorland or Magellanic tundra extends through the Chilean archipielago to 48ºS. This tundra is characterized by prostrate dwarf shrubs, cushion plants, grass-like plants and bryophytes on water-logged terrain that in different combinations form vegetation of scrub or bogs. In sheltered areas, even on the outermost islands, only fragments of the evergreen forest develop. The bogs comprise characteristic species, many with austral affinities such as Astelia, Bolax, Caltha, Donatia, Drapetes, Gaimardia, Lepidothamnus and Phyllachne.

Over the highest mountains, usually limited by a belt of low ‘krumholz’ of prostrate specimens of Nothofagus species, alpine vegetation is found above the forests. The timberline descends from north to south from approx. 1000 m to 500 m. Over it diverse plant communities of dwarf shrubs, cushion heaths, alpine meadows and subnival desert are found. These communities generally increase in richness towards the Patagonian steppes. Similar communities are also found around the glaciers.

The flora of the ecoregion is diverse. The ecoregion is part of the Subantarctic province and shows close relationships to that of the Valdivian temperate forests to the north. This biogeographical province belongs to the Austral realm, and several genera of the ecoregion have representatives or close relatives in Australia, New Zealand and Tasmania, such as Nothofagus trees and Blechnum ferns in the forests, and many cushion and shrub genera of bogs and scrub such as Lepidothamnus, Hebe, Donatia, Gaultheria, Gaimardia, Luzuriaga, Oreobolus, Schoenus and Astelia.

The human populations found in the ecoregion when Europeans established in the area in the 19^th century were aboriginous groups of maritime cultures that navigated the fjords and canals of the archipielago in bark canoes (e.g., Yamana and Alacaluf), and groups of terrestrial culture that hunted and gathered in the mainland and in the island of Tierra del Fuego (e.g., Aush and Shelknam). Contact of these groups with the European colonists produced extinction or dramatic reductions in their populations due to violence or lethal, contagious diseases from the Europeans and the few survivors rapidly lost their ancestral customs. Currently this ecoregion is relatively uninhabited in the west as the climate is too harsh, but a few cities are found more to the east such as Cochrane, Puerto Natales, Punta Arenas and Puerto Williams in Chile, and Ushuaia in Argentina. Many roads have been constructed recently to communicate different parts of the region.

Biodiversity features

Guanacos (Lama guanicoe), Torres del Paine National Park, Chile. Source: Adam Dobrzycki

This ecoregion is not as rich as the Valdivian forests to the north that contain a large number of woody plant genera that are not found in the subpolar Nothofagus forests. Conspicuous genera of the underforest such as the bamboo Chusquea, with Neotropical origin, only reach 48ºS. Most of the epiphytes, and all the climbers are also missing. This has sometimes been related to the effect of the glacial extension during the ice ages that so affected the subpolar Nothofagus forests. Nevertheless, important levels of endemism are found among plants, with several mostly herbaceous species being confined to the ecoregion.

A few examples of conspicuous endemic or nearly endemic species found in this ecoregion are grasses such as Deschamsia kingii, Festuca cirrosa, Poa darwiniana, P. yaganica, and herbs or subshrubs such as Onuris alismatifolia, Ourisia fuegiana, O. ruelloides, Senecio eightsii, S. humifusus, S. websteri, Nassauvia latissima, Acaena lucida, Perezia lactucoides, Viola commersonii, V. tridentata, Phyllachne uliginosa, Lebetanthus myrsinites, Nardophyllum bryoides, Caltha dioneifolia, Hamadryas magellanica, Ranunculus sericocephalus, Gavilea australis, Olsynium obscura, Valeriana sedifolia, Abrotanella submarginata, A. trilobata and A. emarginata. Many of these species are found in the mountains, in alpine regions above the forests where many endemic species of this ecoregion also occur.

Although endemism at the generic level is low, a few endemic, monospecific genera are found, such as Drapetes, Saxifragella and Saxifragodes. Some monospecific genera such as Pilgerodendron (Cupressaceae), the world’s southern most conifer, are especially well represented in the ecoregion. A few Austral genera are especially relevant because they are most diversified in the ecoregion, such as Abrotanella and Ourisia; both have several endemic species. Some genera do not have endemics but are well represented in diversity, frequency or abundance such as the Austral parasitic fungus Cyttaria associated to Nothofagus species. Cryptogms in general, i.e., fungi, lichens, mosses and liverworts, are important in the ecoregion.

Endemism in the flora, however, is not mirrored in the fauna, where there are few endemics. Among the avifauna, most birds of the subpolar Nothofagus forests extend their ranges to the north into the Valdivian forests such as the conspicuous firecrown hummingbird (Sephanoides sephanoides), Magellanic woodpecker (Campephilus magellanicus), rayadito (Aphractura spinicauda), Austral parakeet (Enicognathus ferrrugineus), and black throated huet-huet (Pteroptochos tarnii). Some also extend their ranges into the southern Andean or Patagonian steppes. There seem to be, however, a few near endemics such as two geese (Chloephaga hybrida and C. rubiceps), blackish cinclodes (Cinclodes antarcticus), black throated finch (Melanodera melanodera) and striated caracara (Phalcoboenus australis).

Mammals also tend to have geographic distributions that extend north to other Andean ecoregions or east into the Patagonian steppes. The puma (Puma concolor), two foxes (Dusicyon griseus and D. culpaeus), guanaco (Lama guanicoe), huemul (Hippocamelus bisulcus), pudu pudú (Pudu pudu), and huillín (Lutra provocax) are the largest native animals in the area and are relatively abundant in some parts of the ecoregion. Historically some of these animals, especially huemul, have reduced ranges since the arrival of the Europeans due to hunting, predation by dogs, susceptibility to cattle diseases and competition with cattle and introduced red deer. The most important populations of huemul are found in the area. The only endemic and near-endemic mammals appear to be small ground dwelling mice such as Akodon hershokovitzi, A. lanosus and A. markhami.

Some species of amphibians are characteristic of the ecoregion including Bufo variegatus, and a few are endemic such as Atelognathus grandisonae and Batrachyla nibaldoi. No amphibians have been reported in the Isla Grande de Tierra del Fuego. A few endemic reptiles are found in the eastern limit of the ecoregion, in the ecotone with the steppe, such as Vilcunia periglacialis and Liolaemus magellanicus. Arthropods are relatively little known but are important in many areas, and several damage Nothofagus forest species.

Historical habitation and exploration

Earliest habitation by humans was by the Yaghan people approximately 11,000 years before present. It is somewhat of a mystery how soon Native Americans found their way to the southernmost part of the Americas not long after original crossing of the Bering ice bridge. Nevertheless, the Yaghans had a very hardy lifestyle that not only made use of the forest resources in building their teepee style homes, but included extensive harvesting of marine resources and swimming in the icy waters of this region.

The first detailed scientific European exploration of the region occurred with Charles Darwin's arrival on the HMS Beagle. Darwin spent considerable effort in cataloguing flora and fauna of this ecoregion before journeying further north to explore the more noted Galapogos leg of his trip.

Current status

This ecoregion has several more or less protected areas through all its length. The most important from north to south are Chilean National Parks: Laguna San Rafael, Lago Jeinimeni, Bernardo O’Higgins, Torres del Paine, Alberto De Agostini and Cabo de Hornos, and Argentinean National Parks: Perito Moreno, Los Glaciares and Tierra del Fuego. In Chile there are also several National Reserves: Lago General Carrera, Tamango, Katalalixar, Alacalufes, two Forestal Reserves: Magallanes and Laguna Parrillar, and two Natural Monuments: Laguna de Los Cisnes and Los Pingüinos.

Types and severity of threats

Braided channels of Ainsworth Creek, an area of beaver
invasion, Tierra del Fuego. Source: C.Michael Hogan The subpolar Nothofagus forests are seriously threatened by habitat conversion at the present time. The region has been affected by extensive burning and logging, especially around the main cities and in the more populated areas of the region. A marked increase in the population and tourism in the northern part of the region has been produced by the recent construction of the Chilean Carretera Austral that currently unites Coihaique to Cochrane and Villa O’Higgins. This could produce problems related to the increment of fires, logging and grazing by cattle and sheep. Although the vegetation is probably adapted to grazing by native animals such as huemul and guanaco, the introduction of exotic cattle can have an harmful impact on the ecosystems.

The increase in tourism can have far reaching affects such as the introduction of non-native species. Threats from established exotic species continue to cause threats to this ecoregion. Some exotic animals have been introduced purposely for hunting or for fur or meat such as European rabbit (Oryctolagus cuniculus) and North American beaver (Castor canadensis) have already invaded large areas in the southern portion of this ecoregion. Beavers build dams affecting the regeneration of the forest and the hydrology of the region. Alien plants are a major percentage of the flora, especially in open, disturbed places such as in logged or burnt forest. About 25% of exotic species were most likely introduced with the European colonization and many have been found on the island of Tierra del Fuego. Although sustainable forestry projects are being attempted in this ecoregion, most forestry management is poor and entire stands are turned into chips of low added value.

Further reading

• For a more terse summary of this entry, see the WWF WIldWorld Profile of this ecoregion
• Arroyo, M.T.K., C. Marticorena, P. Miranda, O. Matthei, A. Landero, and F. Squeo. 1989. Contribution to the high elevation flora of the Chilean Patagonia: a checklist of species on mountains on an east-west transect in the Sierra de los Baguales, latitude 50º S. Gayana, Bot. 46: 119-149.
• Arroyo, MT.K., L. Cavieres, A. Peñaloza, M. Riveros & A.M. Faggi. 1996. Relaciones fitogeográficas y patrones regionales de riqueza de especies en la flora del bosque lluvioso templado de Sudamérica. Pages 71-99 in J.J. Armesto, C. Villagrán, and M.T.K. Arroyo, editors, Ecología de los bosques nativos de Chile. Editorial Universitaria, Santiago de Chile.
• Boelcke, O., D.M. Moore, and F.A. Roig, editors. 1985. Transecta botánica de la Patagonia austral. CONICET Argentina, Inst. Patagonia Chile, Royal Society Gran Bretaña, Buenos Aires.
• Brion, C., D. Grigera , J. Puntieri, and E. Rapoport. 1988. Plantas exóticas en bosques de Nothofagus. Comparaciones preliminares entre el norte de la Patagonia y Tierra del Fuego. Mon. Acad. Nac. Cs. Exactas, Fís. y Nat. Buenos Aires 4: 37-47.
• Cabrera, A. L. 1976. Regiones fitogeográficas de la República Argentina. En: Enciclopedia Argentina de Agricultura y Jardinería 2 (1). ACME, Buenos Aires.
• Cabrera, A. L., and A. Willink. 1980. Biogeografía de América Latina. O.E.A. Serie de Biología, Monografía 13. Washington, D.C.: General Secretariat of the Organization of American States.
• Cei, J. M. 1986. Reptiles del centro, centro-oeste y sur de la Argentina. Herpetofauna de las zonas áridas y semiáridas. Museo Regionale di Scienze Naturali, monografie IV. Torino. 527 pp. ISBN: 9879527208.
• Correa, M.N. et al. 1969-1999. Flora Patagónica. Col. Cient. INTA, Buenos Aires. de la Peña, M.R., and M. Rumboll. 1998. Birds of southern South America and Antarctica. Harper Collins, London.
• Donoso-Zegers, C. 1994. Árboles nativos de Chile, guía de reconocimiento. Marisa Cúneo Ediciones, Valdivia.
• Gajardo, R. 1994. La vegetación natural de Chile, clasificación y distribución geográfica. Editorial Universitaria, Santiago de Chile.
• Gamundí, I.J, and Horak. 1993. Hongos de los bosques Andino-Patagónicos. Vazquez Mazzini Editores, Buenos Aires.
• Henriquez, J.M., E. Pisano, and C. Marticorena. 1995. Catálogo de la flora vascular de Magallanes (XII° Región), Chile. Anales Inst. Pat. (Punta Arenas), Ser. Cs. Nat. 23: 5-30
• Hoffmann, J. A. J. 1975. Atlas climático de América del Sur. Mapas de temperatura y precipitaciones medias. WMO, UNESCO, Geneve.
• Hogan, C. Michael. 2008. Bahia Wulaia Dome Middens, Megalithic Portal, ed. Andy Burnham
• Hueck, K. 1978. Los bosques de Sudamérica. GTZ, Eschborn, Germany.
• Lliboutry, L. 1998. Glaciers of South America – Glaciers of Chile and Argentina. Pages 1109-1206 in R.S. Williams, and J.G. Ferrigno, editors, Satellite image atlas of glaciers of the world. US Geological Survey professional paper 1386, Washington DC. ISBN: 0607714530.
• Martinic, M. 1997. The meeting of two cultures, indians and colonists in the Magellan Region. Pages 110-126 in C. Mc Ewan, L.A. Borrero and A. Prieto, editors, Patagonia, natural history, prehistory and ethnography of the uttermost end of the world. British Museum Press, London.
• Moore, D.M. 1983. Flora of Tierra del Fuego. Anthony Nelson, London, and Missouri Botanical Garden, St. Louis.
• Moore, D.M. 1983. The Flora of the Fuego-Patagonian Cordilleras: its origins and affinities. Rev. Chilena Hist. Natural 56: 123-136.
• Moore, D.M. & Goodall, R. N. 1977. La flora adventicia de tierra del Fuego. An. Inst. Patag. Punta Arenas 8: 263-274.
• Murúa, R. 1996. Comunidades de mamíferos del bosque templado de Chile. Pages 113-133 in J.J. Armesto, C. Villagrán and M.T.K. Arroyo, editors, Ecología de los bosques nativos de Chile. Editorial Universitaria, Santiago de Chile.
• Pickett, S. T. A. 1996. Sustainable forestry in Chilean Tierra del Fuego. Trends Ecol. Evol. 11 (11): 450-451.
• Pisano & Dimitri, M. 1973. Estudio ecológico de la región continental sur del área andino-patagónica, I. Anales Inst. Patag. (Punta Arenas) 4 (1-3): 207-272. 1973.
• Redford, K.H., and J.F. Eisenberg. 1992. Mammals of the Neotropics 2, The Southern Cone. Univ. Chicago Press, Chicago & London.
• Rozzi, R., Martínez, D., Willson, M., & Sabag, C. 1996. Avifauna de los bosques templados de Sudamérica. Pages 135-152 in J.J. Armesto, C. Villagrán and M.T.K. Arroyo, editors, Ecología de los bosques nativos de Chile. Editorial Universitaria, Santiago de Chile.
• Taylor, D. W. 1991. Paleogeographic relationships of Andean angiosperms of Cretaceous to Pliocene age. Paleogeography, Paleoclimatology, Paleoecology 88: 69-84.
• Veblen, T.T., C. Donoso, T. Kitzberger & A.J. Rebertus. 1996. Ecology of southern Chilean and Argentinean Nothofagus forests. Pages 293-353 in T.T. Veblen, R.S. Hill and J. Read, editors, The ecology and biogeography of Nothofagus forests. Yale Univ. Press, New Haven.
• Villagrán, C., Moreno, P. & Villa, R. 1996. Antecedentes palinológicos acerca de la historia Cuaternaria de los bosques chilenos. In: J.J. Armesto, C. Villagrán and M.T.K. Arroyo (eds.), Ecología de los bosques nativos de Chile, pp. 51-70. Editorial Universitaria, Santiago de Chile.
• Wardle, P., Ezcurra, C., Ramírez, C. & Wagstaff., S. 2001. Comparison of the flora and vegetation of the southern Andes and New Zealand. New Zealand Journal of Botany 39: 69-108.
• Zuloaga, F.O, and O. Morrone, editors. 1996. Catálogo de las Plantas Vasculares de la República Argentina I. Missouri Botanical Garden, St. Louis.
• Zuloaga, F.O., and O. Morrone, editors. 1999. Catálogo de las Plantas Vasculares de la República Argentina II. Missouri Botanical Garden, St. Louis.
• Zuloaga, F.O., E.G. Nicora, Z.E. Rúgolo, O. Morrone, J. Pensiero, and A.M. Cialdella. 1994. Catálogo de la Familia Poaceae en la República Argentina. Missouri Botanical Garden, St. Louis.