The Argentine Monte (also Low Monte) is located in north-central Argentina, extending along the eastern foothills of the Andes until it reaches the Patagonian steppe, then extends eastwards to the Pacific Ocean. Here thorn scrub and dry grasslands are common. Several river systems meander through this area and create sparse gallery forests. To the west, the Monte transitions into Southern Andean steppe as elevation increases. To the east of the Rio Colorado, the Monte gradually becomes Pampas. The Monte biome is one of the largest dry forest biomes of Argentina. Monte faunal and floral elements are closely related to those of the Chaco biogeographical province, although some Patagonian elements also occur in the central and southwestern part of the Monte.
Location and General Description
The Argentine Monte ecoregion is restricted to the pre-Andean region of western Argentina ranging from Salta (24-35°S) to Chubut (44-20°S) provinces. It extends from 62-54°S on the Atlantic coast to 69-50°S, then from sea level to 2,800 meters (m) elevation. It is a warm scrub desert extending between the Puna, Patagonia, and Chaco ecoregions. The climate is temperate-arid with very little rainfall (between 80 and 250 millimeters per year). The northern and central regions of the Monte receive rain in summer but in the south is colder and rainfall is distributed throughout the year.
The dominant vegetative formation of this ecoregion is scrublands, that at times can be very open. The steppe is formed by resinous evergreen bushes dominated by representatives of the Zygophyllaceae family, such as species from the genera Larrea (jarillas), Bulnesia (retamos) and Plectocarpa (mancapotrillos). They can be found together with Montea aphyla (mata sebo), Bougainvillea spinosa (monte negro) and Prosopis sp. (algarrobo). Other types of vegetation are cactus scrub, xerophilous open woodland, rock associations, psammophilous associations, and halophilous associations. Cactaceae (Trichocereus and Cereus) and Bromeliacea (Dyckia, Deuterochonia, Tillandsia) are more abundant in the northern part of this ecoregion. There are many herbaceous species that appear after the rain, such as Portulaca grandiflora (flor de seda), wild irises and lilies and some grasses. Mesquite trees (Prosopis sp.) form gallery forests on the river borders or can be found were subterranean water is available.
The "jarillal" is the most characteristic community of the Monte ecoregion developing in pockets on plains of sandy or rocky-sandy soil. Larrea cuneifolia colonizes the hotter and drier parts of the Monte, while L. divaricata can only grow as riparian species and L. nitida grows in cold environments as well in the slopes of the Andes. In addition, there are different edaphic communities such as the woods of Prosopis scrubs of Baccharis salicifolia (chilca) and Tessaria dodonaefolia (pájaro bobo) in humid places, Atriplex in clayish soils and Suaeda divaricata and Allenrolfea vaginata in salty soils.
The Monte ecoregion was an important setting for the evolution of temperate biota of the continent. Endemism is a consequence of evolution in isolated areas since the Oligocene. This ecoregion has several endemic species of flora and fauna. Among the plants, we can mention Romorinoa girolae (chica), Gomprhena colosacana var. andersonii from the Sierra de las Quijadas National Park and species with limited distribution in Argentina like verdolaga (Halophytum ameghinoi), a fleshy grass that grows in bogs. The insect fauna is quite well known from the northern part of the Monte where there are a high proportion of endemic genera (10%) and out of species (35%) belong to different families.
The most characteristic mammal fauna of the Monte are the edentates quirquincho chico or piche llorón (Chaetophractus vellerosus), pichiciego (Chlamyphorus tuncatus), carnivores such as puma (Felis concolor), zorro gris chico (Pseudalopex griseus), zorrino chico (Conepatus castaneus), huroncito or hurón chico (Lyncodon patagonicus), the ungulate guanaco (Lama guanicoe), and the rodents cuis chico (Microcavia australis), mara (Dolichotis sp.). The red viscacha rat (Tympanoctomys barrerae) and the pichiciego (Chlamyphorus truncatus) are mammals endemic to this biome; they are also listed as vulnerable according to IUCN categories. The critically endangered rodent Ctenomys validus (tuco-tuco de Guaymallén) and vulnerable rodent species such as Octomys mimax, Andalgalomys roigi and Salinomys delicatus, the mara (Dolichotis patagonum) and in some parts of the ecoregion the guanaco (Lama guanicoe) can all be found in this ecoregion.
Birds include the copetona or martineta común (Eudromia elegans), monterita canela (Poospiza ornata), inambú pálido or petiso (Nothrura darwinii), loro barranquero (Cyanoliseus patagonus), and others. Threatened birds are Falco peregrinus (halcón peregrino) and Harpyhaliaetus coronatus (águila coronada). There are also threatened reptiles species that inhabit the Monte such as the terrestrial turtle (Chelonoidis chilensis) and lampalagua (Boa constrictor). In general, we find various species of reptiles like the lizard or iguana colorada (Tupinambis rufescens) and ophidia such as the falsa yarará (Pseusotomodon trigonatus), yarará ñata (Bothrops ammodytoides), lampalagua (Boa constrictor occidentalis) and falsa coral (Lystrophis semininctus). Among the amphibians, we can mention Pleurodema nebulosa.
In this ecoregion, the most important wetland is the system of lagoons in Guanacache and Rosario in the Mendoza province; a Ramsar site that is home to an interesting diversity of aquatic birds such as Euxenura maguari, Chauna torquata, Plegadis chini, Phoenicopterus chilensis and ducks of the genus Anas. We also find migratory birds like plovers and sandpipers.
Human populations preferred to occupy oases in valleys and other locations close to rivers that make irrigation possible. This is why some sections of the ecoregion were intensively altered but others were not. The forest also underwent significant depredation as man occupied patches and used wood for vineyards, mining, furniture making, construction, and fuel. Overgrazing and deforestation has caused erosion that affected 58 million hectares of the ecoregion.
There are national and provincial protected areas in the ecoregion that represent less than 2% of the surface area. They are placed within the central and southern parts of the ecoregion. They include Los Cardones National Park (Salta province), Sierra de las Quijadas National Park (San Luis province), Talampaya National Park (La Rioja province), Valle Fértil Provincial Reserve (partially within the ecoregion), San Guillermo provincial reserve, Ichigualasto Provincial Park (San Juan province), Telteca Provincial Reserve, Nacuñán Provincial and Biosphere Reserve, Laguna de Llancanelo Provincial Reserve, Divisadero Largo Provincial Reserve (Mendoza province), Lihué Calel Provincial and National Park, La Humada Provincial Reserve, La Reforma Provincial Reserve, Salitral Levalle Provincial Reserve (La Pampa province), Cinco Chañares Provincial Reserve, Complejo Islote Lobos Provincial Reserve, Caleta de los Loros Provincial Reserve (Rio Negro province), El Mangrullo Provincial Reserve (Neuquén province), and Península de Valdés provincial Reserve (Chubut province). Even with this extensive list of protected areas the northern parts of the Monte ecoregion is not protected nor are large tracts of land needed by many species to complete their life cycles.
Types and Severity of Threats
The Monte, as well as in the Chaco and Patagonia lowland, is experiencing seriously damaging effects due to human activities, especially overgrazing by goats, sheep, and cattle; clear cutting for fuel; and land clearing for agriculture, mining, and oil exploration. The deforestation and selective extraction of hardwood and clear cutting of mesquite forests began at the late 19th and early 20th centuries and continues today. Anthropogenic activities during the past 150 years have led to pronounced desertification, disruption of habitats and changes in the biodiversity and geographic ranges of many species.
Justification of Ecoregion Delineation
The delineations for the Argentine Monte were derived from Daniele and Natenzon, and linework follows their classification of "Monte y Cardonales de la Prepuna (woodlands and thistle of the prepuna)" region. Other resources consulted include Cabrera and Morello.
Additional Information on this Ecoregion
- For a shorter summary of this entry, see the WWF WildWorld profile of this ecoregion.
- To see the species that live in this ecoregion, including images and threat levels, see the WWF Wildfinder description of this ecoregion.
- World Wildlife Fund Homepage
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