The San Guillermo Biosphere Reserve in the northwest of San Juan Province, Argentina, represents the mixed mountain and highland systems in the foothills and mountains of the Andes. The San Guillermo National Park occupies the core zone.
The San Guillermo Biosphere Reserve in the northwest of San Juan Province, Argentina, represents the mixed mountain and highland systems in the foothills and mountains of the Andes occupying the west sector of Catamarca, La Rioja, San Juan and Mendoza Provinces.
The buffer and transition zones fall within what was originally set up as a provincial reserve, while the San Guillermo National Park occupies the core zone.
The altitude of the Biosphere Reserve varies between 1,000 and 6,000 m (3,300 and 19,700 ft). It totals 981,000 ha (2,420,000 acres) and consists of arid mountain ranges with no permanent water courses.
The Biosphere Reserve constitutes two phytogeographical regions: the Gran Chaco and the Andean Region. The Gran Chaco (or Dry Chaco) is a humid and swampy region extending from Bolivia and Paraguay to northern Argentina.
The Andean Region consists of steep and rugged highlands with river valleys and lakes, which support migrating species as the Andean flamingo and mammals as vicuna (Vicugna vicugna) and guanaco (Lama guanicoe).
The Biosphere Reserve contains grasslands with or without shrubs and sub-desertic open matorral with valleys and steep slopes. It also comprises important archaeological sites and ancient indigenous villages in the Cerro las Tórtolas, Cerro las Flechas and Cerro del Toro, an ancient ceremonial monument.
The flora consists of scattered dwarf shrubs, interspersed with coarse grasses and herbaceous plants, and much bare ground. The shrubs include Adesmia, Patrastrephia, Fabiana, Azorella and Ephedra. Grasses present include Stipa, Calamagrostis and Festuca and flowering plants include Astragalus, Tropaeolum, Phacelia and Glandularia.
Fauna includes the vicuña, the guanaco, the culpeo fox, the Andean mountain cat, the cougar, the southern viscacha, the short-tailed chinchilla, the Darwin's rhea, various ducks and geese, and the Andean condor.
Only 300 people (1999) live in the Biosphere Reserve temporarily, engaged mainly in mining activities, some cattle raising and hunting.