The Patagonian grasslands ecoregion extends from near the tip of the southern cone in Argentina, northwards across eastern Tierra del Fuego, then extends just north of the Straits of Magellan to the Rio Gallegos. The Falkland Islands are also included in this ecoregion. Habitats in this ecoregion include tundra grasslands in the northern portion, high latitude Andean meadows in the central portion, deciduous thickets along the southern extremes, and swamp forests on the Falkland Islands.
Much of this region in southern Argentina and Chile has been ecologically altered due to extensive grazing of livestock introduced by Europeans in the 1800s. Certain coastal portions of this ecoregion are breeding grounds for penguins such as the Magellanic penguin.
Location and General Description
Darwin's rhea, Patagonian grassland, Chile. @C.Michael Hogan The Patagonian grasslands are located at the bottom tip of South America. The region extends from the Santa Cruz Province in Argentina to the Tierra del Fuego in Chile and Argentina. The ecoregion also includes the Islas Malvinas or Falkland Islands on the Atlantic Ocean. The Strait of Magellan divides the ecoregion into two parts. The northern section is part of mainland South America and the southern section constitutes the Tierra del Fuego Island group. The Patagonian grasslands show a topographic relief of low mountains, mesas, and plains. The soils are rich with high concentrations of fine materials and have a lot of organic material. The climate is cold and humid with 200 to 300 millimetres (mm) of rain per year and an average temperature below 8°C.
The dominant vegetation of this ecoregion consists of grass-steppe interspersed with shrubs. Some of the plant species include the coirón blanco (Festuca pallescens), senecio (Senecio patagonicus) and Palntago maritime. Atriplex reichei and Lepidophyllum cupressiforme (a stocky shrub with alternating scaly leaves) are found in salty soils near the sea. Common genera in the region include Adesmia, Anarthrophyllum Berberis, Chuquiraga, Lycium, Mulinum, Schinus and Verbena. In the Tierra del Fuego the steppe's dominant vegetation is coirón (Festuca gracillima), a perennial grass 30 - 70 centimeters (cm) high, with thin, stiff, pleated leaves. Other grasses include Poa atropidiformis, Trisetum sp., and Hordeum comosum. The bottom of the valleys and plains are dominated by cebada silvestre (Hordeum comosum), with Alopecurus antarticus, Phleum conmutatus, Poa pratensis, Agrosti sp..
Wetlands are of great importance in this ecoregion including the following: marsh and lagoons of Tero, marsh of Rio Pelque, Lago Argentino, lagoons of Puerto Bandera, Lake Viedma, lagoons of the Meseta del Tobiana, lagoons Escarchados. Areas with a high importance in the coastal zone include Río Santa Cruz, Monte León, Río Coig, Ría Gallegos, Cabo Vígenes, Bahía San Sebastián, Río Grande, Península Mitre, Canal Beagle, and Isla of the Estados.
The fauna is very diversified in this region. Some of the mammals include the Patagonian Mara (Dolichotis patagonum), the Southern Viscacha (Lagidium viscacia), the Wolffsohn's Viscacha (Lagidium wolffsohni), the Patagonian Weasel (Lyncodon patagonicusi), the Humboldt's Hog-nosed Skunk (Conepatus humboldti), the puma (Felis concolor), the Falkland Island wolf (Dusicyon australis), the Guanaco (Lama guanicoe). There are numerous birds in the ecoregion, some of them are the Lesser rhea (Pterocnemia pennata), the Patagonian tinamou (Tinamotis ingoufi), the Black-chested buzzard-eagle (Geranoaetus melanoleucus), the Peregrine (Falco peregrinus), the Band-winged nightjar (Caprimulgus longirostris), the Patagonian mockingbird (Mimus patagónicus), and the Patagonian yellowfinch (Sicalis lebruni).
The Patagonian grasslands and the southern part of the Patagonian steppe ecoregion have various endemic birds. These birds inhabit various types of habitat from freshwater lakes to coastal water and rocky shores. Endemic birds frequently found in the Santa Cruz Province and north of the Straits of Magellan include the hooded grebe (Podiceps gallardoi), Magellanic plover (Pluvianellus socialis), chocolate-vented tyrant (Neoxolmis rufiventris), canary-winged finch (Melanodera melanodera), short-billed miner (Geositta antarctica), ruddy-headed goose (Chloephaga rubidiceps), and striated caracara (Phalcoboenus australis), which is found also south of the Straits of Magellan. The blackish cinclodes (Cinclodes antarcticus) is found in the Tierra del Fuego Island. Endemic birds of the Falkland Islands are the Falkland steamerduck (Tachyeres brachypterus) and the Cobb's wren (Troglodytes cobbi). The Islands are also very important for various seabirds including the Gentoo penguins (Pygoscelis papua).
Threatened species in the ecoregion include the cauqué colorado (Chloephaga rubidiceps), the ñandú petiso (Pterocnemia pennata), the Patagonian Mara (Dolichotis patagonum), the guanaco (Lama guanicoe), the zorro gris chico (Dusicyon griseus), and the lobo de dos pelos (Aretocephalus australis).
The human population in the ecoregion is low, but the area has been affected by grazing livestock and introduced herbivores. The natural grassland, in particular tussock grass, has been destroyed, and endemic birds in the area rely directly or indirectly on this grass. There are not many protected areas in this ecoregion; some of them are Dicky Private Reserve, the Reserva Costa Atlántica Tierra del Fuego, and Magallanes National Reserve.
Types and Severity of Threats
Desertification is the most serious threat to this ecoregion. Overgrazing by cattle and sheep deteriorates the scarce vegetation cover, leaving the soil exposed to processes of erosion. The destruction of the natural habitat has severely affected the avifauna in the area, especially endemic species. Three species are of particular concern: Great grebe (Podiceps gallardoi), with few than 5000 individuals remaining, Ruddy-headed goose (Chloephaga rubidiceps), with a serious decline in population numbers, and Striated caracara (Phalcoboenus australis), whose numbers have declined due to hunting.
Justification of Ecoregion Delineation
The delineations for the Patagonian Grasslands were derived from Daniele and Natenzon, and linework follows their classification of "Pastizales Australes (austral grasslands)" region. Other resources consulted include Cabrera and Morello.
- For a terser summary of this entry, see the WWF WildWorld profile of this ecoregion.
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- Villamil, Carlos B. 1997. Patagonia. S.D. Davis, V.H. Heywood, O. Herrera-MacBryde, J. Villa-Lobos, and A.C. Hamilton, editors. Centres of plant diversity: A guide and strategy for their conservation, Vol. 3 The America. IUCN, WWF, Oxford, U.K. ISBN: 283170197X
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