Argentine Monte

The Argentine Monte (NT0802), or Low Monte, is an ecoregion of dry thorn scrub and grasslands in Argentina. It is one of the driest regions in the country. Human settlements are mainly near water supplies such as rivers or oases. Deforestation and over-grazing around these settlements have caused desertification.

The Argentine Monte is in north-central Argentina, and has an area of 354,192 square kilometres (136,800 sq mi). It is to the east of the Andes and extends from Salta Province in the north to Chubut Province in the south. It extends from the eastern foothills of the Andes to the Atlantic Ocean. The ecoregion merges into the Patagonian steppe in the south and southwest. The Dry Chaco lies to the northeast, and the Espinal is to the east.

In the northwest it borders the High Monte. Some consider the High Monte a separate ecoregion, while others consider it a part of the Argentine Monte.

Elevations range from sea level on the Atlantic coast to 2,800 metres (9,200 ft). The region contains parts of the watersheds of the Rio Negro and Rio Colorado. The Lagunas de Guanacache, Desaguadero y del Bebedero in Mendoza Province form the most important wetland in the ecoregion, designated a Ramsar site. This is a long chain of lagoons and marshes covering 10,000 square kilometres (3,900 sq mi) fed by the Mendoza and San Juan rivers, which drains into the Desaguadero River. The lakes and streams are mostly seasonal or intermittent.

The ecoregion is by far the driest part of Argentina. The Köppen climate classification is "BSk": arid, steppe, cold arid. Annual precipitation is 80 to 250 millimetres (3.1 to 9.8 in). In the north and central regions there is more rain in summer. In the colder south the monthly rainfall is more evenly distributed. At a sample location at coordinates 38°15′S 67°15′W / 38.25°S 67.25°W / -38.25; -67.25 the mean temperature ranges from 6.3 °C (43.3 °F) in July to 23.1 °C (73.6 °F) in January. The yearly average mean temperature is 15 °C (59 °F). Annual precipitation is about 175 millimetres (6.9 in). Monthly precipitation ranges from 5.4 millimetres (0.21 in) in July to 25.7 millimetres (1.01 in) in October.

The Argentine Monte is in the Neotropical realm, in the temperate grasslands, savannas, and shrublands biome.

Flora are typically thorn scrub and dry grassland, with relatively low plant diversity. There are thin gallery forests along the rivers. There are areas of cactus scrub, xerophilous open woodland, and vegetation adapted to rocky, sandy and salty conditions. In some areas the scrub is very open. The steppe contains resinous evergreen bushes, mainly from the family Zygophyllaceae and the genera Larrea, Bulnesia and Plectocarpa. Other species are Monttea aphylla, Bougainvillea spinosa and Prosopis species.

In the north cacti of the genera Echinopsis and Cereus and bromeliads of the genera Dyckia, Deuterocohnia and Tillandsia are more common. Herbaceous plants appear after rain showers, including Portulaca grandiflora, irises, lilies and grasses. On the river edges or where there is underground water there are gallery forests of Prosopis species. Larrea cuneifolia is found in hot and dry areas, Larrea divaricata along the streams and Larrea nitida in cooler areas and mountain slopes. Other plants found in different conditions include Baccharis salicifolia, Tessaria dodonaefolia, Suaeda divaricata and Allenrolfea vaginata. Several endemic species have evolved in isolation since the Oligocene such as Ramorinoa girolae and Gomphrena colosacana, found in the Sierra de las Quijadas National Park, and Halophytum ameghinoi, a succulent herbaceous plant in the Halophytaceae family.