CONICET | Buscador de Institutos y Recursos Humanos

In southern South America, widespread aridity has been postulated during the mid Holocene, followed by wetter conditions in the late Holocene. West-central Argentina experienced a hiatus in the archeological record during the mid Holocene, which has been attributed to scarce resources during dry conditions; however, there is little paleoenvironmental information available from this area to test this hypothesis. New Holocene records from the upper Atuel River basin (34°47S,69°52W; 2000 m asl) provide information on the vegetation, climate, and fire history of the region and offer an important comparison with other published records. Pollen data from Laguna El Sosneado and nearby peat records show a period of shrub steppe between 6400-3200 cal yr BP, suggesting moderate but wetter-than-present conditions. During this interval, high-resolution charcoal records suggest that fires were frequent. Between 3200-1900 cal yr BP, an increase in Poaceae, Apiaceae and other shrubs suggests a period of high effective moisture. High fire activity at this time is explained by the greater abundance of fine fuels. Sparse vegetation and dry conditions are inferred between 1900-300 cal yr BP based on an increase in Chenopodiaceae, Asteraceae, Ephedra, Schinus. The lack of fuels resulted in extremely low fire activity. The last 300 years mark the development of modern conditions and evidence of intensive land use. Evidence of wet conditions in the Andean foothills during the middle Holocene contrasts with postulated arid conditions, especially in Chile. We suggest that the archeological hiatus implies low dispersed populations, high mobility, or poor site preservation, rather than regional abandonment.

enviar mensaje