Patagonian Desert: Patagonian or Magellanic Steppe Ecoregion (Argentina)

Patagonian Desert: Patagonian or Magellanic Steppe Ecoregion (Argentina)

Tue, 10/23/2018 - 15:17
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The Patagonian Desert, also known as the Magellanic Steppe, is a semiarid scrub plateau covering nearly all of the southern portion of mainland Argentina. It is the largest desert in Argentina and is bounded by the Patagonian Andes and the country of Chile to the west.

Patagonian Desert

The Patagonian Desert, known as the Patagonian or Magellanic Steppe, is a semiarid scrub plateau covering nearly all of the southern portion of mainland Argentina. It is the largest desert in Argentina and is the 8th largest desert in the world by area, occupying 673,000 sq km (260,000 sq mi).

The region is approximately bounded by the Patagonian Andes to the west, the Colorado River to the north, the Atlantic Ocean to the east, and the Strait of Magellan to the south.

The region south of the strait (Tierra del Fuego), divided between Argentina and Chile, is often included in the Patagonia region. To the north, the desert grades into the Cuyo Region and the Pampas.

Shrubby and herbaceous plant species dominate the central parts of the steppe. To the west, where precipitation is higher, grasses replace bushes.

Topographically, the deserts consist of alternating tablelands and massifs dissected by river valleys and canyons. The more western parts of the steppe host lakes of glacial origin and grade into barren mountains or cold temperate forests along valleys.

The Patagonian Desert is a large cold winter desert where the temperature rarely exceeds 12 °C (54 °F) and averages just 3 °C (37 °F). The region experiences about seven months of winter and five months of summer. Frost is not uncommon in the desert, but snow is rare year-round due to the arid condition.

The burrowing owl, lesser rhea, guanaco, tuco-tuco, mara, pygmy armadillo, Patagonian weasel, puma, Patagonian gray fox, desert iguana, western ribbon snake, and various species of eagle and hawk are a few of the variety of animals living in the region.

Patagonian or Magellanic Steppe

The Patagonian, or Magellanic, steppe ecoregion mainly covers the Patagonia geographic region of Argentina from the Atlantic Ocean shore to barely across the border into Chile. The Peninsula Valdés is an outlier of this ecoregion, slightly north of the main body.

The topography of this ecoregion includes low-lying mountains, plateaus, and plains. Soils are variable but generally rocky-sandy and poor in fine materials and organic matter.

The climate is arid and cold, with snow during the winter and frosts nearly year-round. Precipitation averages typically less than 200 mm (8 in) annually. A characteristic of the Patagonian climate is the constant drying wind that blows with great force from the western sector, particularly in the summer months.

In general, the vegetation of this steppe ecoregion is xerophytic and highly adapted for protecting against drought, wind, and herbivores. Dwarf and cushion shrubs are the most widely occurring vegetation type.

Flora and Fauna

This ecoregion has high levels of endemism in both plants and animals. Vegetation includes two endemic species of the genus Prosopis, one species of Larrea, and species of the genera Lycium and Schinus.

Shrubs species of Acantholippia, Benthamiella, Nassauvia, and Verbena genera grow in the region and cushion plants of Mulinum spinosum and Brachyclados caespitosus and tuft grasses, the most common being Poa and Stipa species.

Taller woody shrub species of Anarthrophyllum, Berberis, Schinus and Verbena can grow up to 3 m (10 ft) tall and often indicate a change in vegetation from the flat open steppes.

There are three main types of vegetative communities:

  • semi-desert (45%)
  • shrub-steppe (30%)
  • grass-steppe (20%)

Desert-like areas also exist with little or no vegetation cover, and wet meadow areas have close to 100% cover.

Typical mammals of the Patagonian Steppe include the Patagonian mara, chinchilla, Patagonian weasel, Wolffsohn's viscacha, Humboldt's hog-nosed skunk, puma, Argentine gray fox, guanaco, and the Patagonian opossum.

Notable reptiles include the prickly gecko, Liolaemus fitzingeri, and Darwin's iguana.

Species of concern include the near-threatened Patagonian mara, the endangered south Andean deer, the critically endangered hooded grebe, and the social tuco-tuco.

Protection Status

Despite the low density of the human population, this ecoregion has been seriously affected due to the environment's fragility.

The primary threat to this ecoregion is desertification due to over-grazing, primarily by sheep, which damages the limited plant coverage and exposes the soil to erosion.

In addition to several Provincial Reserves, protected areas in this ecoregion include:

Map depicting the location of the Patagonian steppe (in purple)

Map depicting the location of the Patagonian steppe (in purple)