Central Andean Dry Puna: Salt Flats, the World's Highest Woody Plants, and the Andean Cat's Rocky Refuge

The Central Andean dry puna is a cold, arid grassland and shrubland that occupies the southern part of the central Andes along the Cordillera Occidental. It lies between the tree line and the permanent snow line, mostly above about 3,000 m (9,850 ft), and it is the driest of the three puna ecoregions described in our Puna article, receiving less than 400 mm (16 in) of rain a year, with an eight-month dry season. Its landscape is one of snow-capped volcanoes, high plateaus, shallow lagoons, and salt flats.

Where the Dry Puna Lies

In Bolivia, the ecoregion covers parts of the departments of La Paz, Oruro, and Potosí; in Argentina, the provinces of Jujuy, Salta, Catamarca, and La Rioja; and in Chile, the regions of Arica y Parinacota, Tarapacá, Antofagasta, and Atacama. To the west it meets the Atacama Desert, to the north it grades into the Central Andean puna and the Central Andean wet puna, and to the south it gives way to the Southern Andean steppe. Only about 15 percent of the ecoregion lies within protected areas.

Salt Flats and the Lakes That Made Them

The dry puna's salt flats, or salars, have two different origins. The northern ones are relics of vanished lakes: a succession of paleolakes named Minchin, Tauca, and Coipasa rose and fell across the southern Altiplano between roughly 42,000 and 11,500 years ago, and at its peak Lake Tauca stretched more than 600 km (370 mi), comparable in size to Lake Michigan, and was up to about 140 m (460 ft) deep. As the climate dried, the lakes shrank to Lake Poopó and left behind Uyuni, the world's largest salt pan at nearly 10,000 sq km (3,900 sq mi), and Coipasa. Farther south, salars such as Atacama, Arizaro, Chalviri, Olaroz, Cauchari, and Hombre Muerto occupy separate closed basins, where water arrives from snowmelt and streams and leaves only by evaporation, concentrating salts and, increasingly, lithium.

Plants of a Treeless Plateau

The vegetation is a sparse mosaic of tropical alpine herbs, dwarf shrubs, and bunchgrasses adapted to cold, drought, and intense sunlight. Resinous shrubs known as tolas, such as Parastrephia lepidophylla and species of Lampaya, cover the plains; bunchgrasses such as Festuca orthophylla and species of Stipa dominate the steppe; and cushion plants, above all llareta (Azorella compacta), grow as hard, dense mats on rocky slopes. Where meltwater or springs keep the ground wet, bofedales form, high-altitude wetlands of cushion plants, sedges, and rushes that feed vicuñas, llamas, and alpacas through the dry season.

The World's Highest Woody Plants

Polylepis, a genus of small trees in the rose family, grows higher than any other tree genus on Earth, and the dry puna's Polylepis tarapacana is the woody plant found at the highest elevations in the world, forming woodlands at 4,400 to 4,900 m (14,440 to 16,080 ft) in Chile's Lauca National Park. Pollen preserved in the Salar de Uyuni suggests that P. tarapacana communities were an important part of the Altiplano's vegetation during the last Ice Age. Today, the woodlands survive as scattered patches on rocky slopes and around volcanoes such as Sajama, where Bolivia created its first protected area to safeguard its queñua forests.

Animals of the Dry Puna

Vicuñas (Vicugna vicugna) roam the steppe and wetlands, joined by herds of domestic llamas (Lama glama) and alpacas (Vicugna pacos) kept by Aymara and other Andean herders, and the story of the vicuña's recovery from the brink of extinction is told in our Puna article. The puma (Puma concolor), the culpeo or Andean fox (Lycalopex culpaeus), mountain vizcachas (genus Lagidium), and the Andean hairy armadillo (Chaetophractus nationi) share the rocky ground.

The ecoregion's flagship species is the Andean cat (Leopardus jacobita), an Endangered felid weighing only about 4 kg (9 lb), with fewer than 2,200 adults estimated across the Andes of Argentina, Bolivia, Chile, and Peru. It depends on rocky outcrops and on its preferred prey, the mountain vizcacha, and a 2020 habitat-modeling study of Chile's dry puna found only about 920 sq km (356 sq mi) of suitable area, broken into scattered patches. Another rarity, the short-tailed chinchilla (Chinchilla chinchilla), was rediscovered in Bolivia in April 2017 when a ranger in the Eduardo Avaroa reserve found a burrow with four animals under a boulder near Laguna Colorada.

Birds, Frogs, and Lizards of the Margins

The dry puna's best-known birds are its three flamingos, the Chilean (Phoenicopterus chilensis), Andean (Phoenicoparrus andinus), and James's or puna (Phoenicoparrus jamesi) flamingos, which feed and nest on its salt lakes. Most of the ecoregion's endemic birds, however, live in the Polylepis woodlands and scrub along its lower margins. WWF's ecoregion profile lists the Endangered Cochabamba mountain-finch (Poospiza garleppi); the Vulnerable maquis canastero (Asthenes heterura), chestnut canastero (Asthenes steinbachi), and rufous-bellied saltator (Saltator rufiventris); and the Near Threatened wedge-tailed hillstar (Oreotrochilus adela) and Tucumán mountain-finch (Poospiza baeri). The frog Telmatobius huayra is an endemic amphibian, and two recently discovered lizards of the genus Liolaemus were recorded in Bolivia's Eduardo Avaroa reserve.

Protected Areas

Most protected areas in the ecoregion were created as faunal reserves. In Bolivia, the Eduardo Avaroa Andean Fauna National Reserve covers 714,745 hectares (about 1.77 million acres) and protects the lagoons and the birds that use them, while Sajama National Park (1,002 sq km, or 387 sq mi) lies beneath Sajama, Bolivia's highest peak at 6,542 m (21,463 ft). In Argentina, the Olaroz-Cauchari Flora and Fauna Reserve protects 180,000 hectares (about 444,800 acres) of salars and steppe. In Chile, the altiplano's wetlands, volcanoes, and salt flats are protected in the Lauca Biosphere Reserve, Volcán Isluga National Park, Salar del Huasco National Park, and Los Flamencos National Reserve.

Pressures on the Puna

Centuries of livestock grazing, burning, firewood collection, and crop clearing have left their mark. WWF identifies the clearing of Polylepis woodlands for farming, fuel, and pasture as a major threat to the ecoregion's endemic birds, and the overuse of P. tarapacana and llareta for fuelwood endangers both plants. These pressures have been compounded by lithium and other mineral mining from the salars, which draws on the same brine-rich groundwater that sustains the bofedales and flamingo lagoons.

Conclusion

The dry puna looks empty from a distance, but it is one of the Andes' most distinctive ecosystems, where woodlands grow higher than anywhere else on Earth and ancient lake basins still shape the movements of flamingos and herders. Its future will depend on how its scarce water is shared among wildlife, herding communities, and the mines.

Map depicting the location of the Central Andean dry puna ecoregion (in purple).