Patagonian desert

Abstract

The Argentinian Patagonia is a vast area (790,000-km2) of southern South America between 36° and 55°S. Almost 90% of the area is arid, semiarid or dry- subhumid (drylands) and covers important and heterogeneous ecological zones that are determined primarily by climatic gradients and a highly complex geomorphology. That gives rise to different soils (mainly Aridisols, Entisols and Mollisols) and vegetation types (semideserts, shrub steppes, shrub-grass steppes, grass-shrub steppes and grass steppes). Grazing (mainly sheep) and, to a lesser extent, fires are the principal anthropogenic stress factors that have dramatically altered the structure and functioning of these ecosystems. Climatic models predict an increase in aridity for Patagonian drylands, which could accentuate the negative effects of overgrazing on ecosystem health and reduce the capability of Patagonian ecosystems to provide essential services such as forage production and carbon sequestration. The adjustment of grazing management practices could mitigate negative effects but requires routine monitoring of ecosystem structure and functioning, for which the MARAS system (Spanish acronym for Environmental Monitoring for Arid and Semi-Arid Regions) has been developed.