Southern South America: Eastern Argentina

The Humid Pampas ecoregion occupy one of the most human populated areas in Argentina. The ecoregion consists of the plains, many rivers, and lagoons. The natural vegetation in the area is composed of grasslands and xeric woodland. There are various endemic animals that are threatened by habitat destruction and degradation. The ecoregion is considered endangered and is regarded as a high priority conservation area at the regional scale.

  • Scientific Code
  • Ecoregion Category
  • Size
    93,000 square miles
  • Status
  • Habitats

Location and General Description
The Humid Pampas occupy the plains in the east of Argentina, taking up most of the province of Buenos Aires. Horizontal plains and very soft undulations with low peaks that emerge like islands characterize the relief of this area. There are a few slow moving, undulating rivers and many lagoons with fresh and salt water (Cabrera 1976). The pampas plains originated in packed sediment from a large sinking tectonic pit that extends to the Chaco. The soils are gray or black with a subsoil of loess or lime. In the west there are sandy soils, while in the southeast there is a thick layer of calcium under thin soil. In the mountains we find very thin soils of rack crystals and sandstone (Cabrera 1976). The climate is hot with rain throughout the year. The climatic conditions, combined with the geochemical characteristics of the sedimentary materials and the vegetative cycles of the pasture like grasslands, have favored the development of soils with high organic and nutrient content. These characteristics make the soil excellent for vegetative growth.

The original vegetation in this area is moderate grassland that is dominated by flechillar, highly eatable food for grazers. The dominant grasses are Stipa, Piptochaetium, Aristida, melica, Briza, Bromus, Eragrostis and Poa. Among the grasses there are many annuals such as Micropsis, Berroa, Gamochaeta, Chaptalia, Aster, Chevreulia, Vicia, Oxalis, Adesmia and Daucus. Common sufrutices and shrubs include Margyricarpus, Heimia, Baccharis, and Eupatorium (Cabrera 1976).

Different soil compositions and geomorphic factors affect the distribution of wildlife and make room for other vegetative groups such as halophyte plants including Atriplex, Larrea divaricata, L. cuneifolia, Suaeda, and Tricomaria. Dominant xeric vegetation in the southern part of the ecoregion includes Prosopis flexuosa, P. chilensis, P. juliflora, and P. kuntzei. Other plants are Jodina rhombifolia, Loxopterygium brachypterum, Pentapanax angelicifolius, Schinopsis lorentzii and Schinus dependens (UNESCO 1981).

In this area there are numerous unique habitats among which we could mention: Cangrejales de Samborombón, Punta Rasa, Albufera Mar Chiquita, Laguna de los Padres, Cabo Corrientes, Complejo Laguna Salada Grande, Laguna Sauce Grande, Humedales del Partido 9 de Julio and Sistema "Encadenadas de Chascomus". Within the Ramsar sites in this region we find Bahía Samborombón (Canevari et al. 1998).

Biodiversity Features
The pampas region lacks endemic vegetation of importance (Cabrera, 1976). However, there are numerous endemic animals including Limnornis curvirostris, Larus atlanticus and Liophis elegantísima. Species in danger of extinction include the pampas deer (Ozotoceros bezoarticus celer) a very important herbivore in this area, the loica pampeana (Sturnella defilippi), Limosa haemastica, Chloephaga rubidiceps, Laterallus spilopterus and Coturnicops notata. (Chebez 1988; Bertonatti y González 1992; García Fernández et al. 1997; Canevari et al 1998).

Among the fauna we find great herbivores such as the (Ozotoceros bezoarticus celer) and the guanaco (Lama guanicoe), carnivores such as the puma (Felis concolor), Geoffroy’s cat (Felis geoffroyi), pampa fox (Dusicyon gymnocercus), zorrino común (Conepatus chinga) and grison (Galictis cuja). Other mammals in the area are the vizcachas (Lagostomus maximus), the cuis pampeano (Cavia aperea), the nutria (Myocastur coypus), and the opossum (Didelphis albiventris).

Some of the birds include the ñandú (Rhea americana), the chajá (Chauna torquata), the perdiz chica (Nothura maculosa), the martineta colorada (Rynchotus rufescens); and birds associated with aquatic environments such as the gallareta chica (Fulica leucoptera), the cuervillo de cañada (Plegadis chihi), the cigüeña americana (Euxenura maguari) and others. The marshlands of the ecoregion are important conservation centers for birds that migrate from the Northern Hemisphere to the Patagonia.

Current Status
Little is left of the natural habitat in the Humid Pampas. This is one of the most heavily populated areas of Argentina that has been extensively used for agriculture and cattle grazing. Natural vegetation grows in small patches that persist along the railroad tracks and in some abandoned fields left to rest for many years. Only certain species of animals live in this disturbed and altered habitat. The region has been classified as a maximum priority ecoregion at regional scale (Dinerstein, et al. 1995).

Some of the protected areas that fall within the ecoregion are the Reserva Natural Estricta Otamendi, Reserva de la Biosfera Parque Costero del Sur, Reserva Provincial Samborombón, Reserva Provincial Rincón de Ajó, Reserva Provincial Dunas del Atlántico Sur, Reserva Municipal Rufino, Reserva Municipal Costanera Sur (in part), Reserva Municipal Sierra del Tigre (Tandil), Reserva Municipal El Curral (Laguna de los padres), Reserva Municipal Mar del Plata (puerto), Reserva Municipal Mar Chiquita, Reserva Privada Estancia El Destino, Reserva Privada Campos del Tuyú.

Types and Severity of Threats
There are two severe threats in the region: conversion of remaining natural habitats for agriculture and degradation through over-grazing are severe threats (Dinerstein et al. 1995). Burning and draining of lands are also threatening remaining habitats (Dinerstein et al. 1995) that could possibly affect protected areas.

Justification of Ecoregion Delineation
The delineation’s for the Humid Pampas were derived from Daniele and Natenzon (1994), and linework follows their classification of "Pastizales de la Pampa Húmeda (grasslands of the humid pampas)" region. Other resources consulted include Cabrera (1976) and Morello (1968).

Bertonatti, C.Y.F. González. Lista de Vertebrados Argentinos Amenazados de Extinción. FVSA..

Cabrera, A.L. 1976. Regiones Fitogeográficas de Argentina. Enciclopedia Argentina de Agricultura y Jardinería. Tomo II. Fascículo I. Editorial ACME S.A.C.I..

Canevari P., D.E. Blanco, E. Bucher, G. Castro, y I. Davidson. 1998. Los Humedales de la Argentina. Clasificación, situación actual, conservación y legislación. Wetlands International.

Chebez, J. C. 1988. El deterioro de la Fauna. En El deterioro del Ambiente en la Argentina (suelo, agua, vegetación, fauna). Fundación para la Educación, la Ciencia y la Cultura, Buenos Aires, Argentina.

Daniele, C., and C. Natenzon. 1994. Regiones Naturales de la Argentina. Draft map. Argentina National Parks Department, Buenos Aires, Argentina.

Dinerstein, E., D.M. Olson, D.J. Graham, A.V. Webster, S.A. Primm, M.P. Bookbinder y G. Ledec. 1995. Una evaluación del estado de conservación de las ecoregiones terrestres de América Latina y el Caribe. Publicado en colaboración con el Fondo Mundial para la Naturaleza, Banco Mundial, Washington, D.C..

García Fernández, J.J., R.A. Ojeda, R.M. Fraga, G.B. Díaz, y R.J. Baigún. 1997. Mamíferos y aves amenazados de la Argentina. FUCEMA, SAREM, AO del Plata, APN, Buenos Aires, Argentina.

Morello, J. 1968. La vegetación de la República Argentina, No. 10: Las grandes unidades de vegetación y ambiente del Chaco Argentino. Buenos Aires, Argentina.

UNESCO. 1981. Vegetation Map of South America: Explanatory notes. UNESCO, Paris.

Prepared by: Claudia Dellafiore
Reviewed by: In process