La Payunia

La Payunia Provincial Reserve is one of Argentina's most spectacular volcanic landscapes, protecting an immense lava field in southern Mendoza province where more than 800 volcanic cones dot a basaltic plateau stretching to the horizon. Covering approximately 659,000 hectares, the reserve is one of the largest concentrations of Quaternary volcanoes in the world, with eruptions occurring as recently as a few thousand years ago in geological terms. The reserve sits at elevations between 1,500 and 3,500 meters in the Patagonian steppe transitional zone, where the high Andes give way to the vast southern plains. La Payunia is also home to the largest wild guanaco population in Mendoza province, making it an outstanding destination for both geological and wildlife tourism.

La Payunia is celebrated for hosting the largest concentration of guanacos (Lama guanicoe) in Mendoza province, with herds of hundreds to thousands of animals moving across the volcanic steppe. Pumas (Puma concolor) are the apex predator, hunting guanacos and smaller mammals. Andean condors (Vultur gryphus) soar overhead, scavenging carcasses across the open terrain. Lesser rheas (Rhea pennata) and Patagonian maras (Dolichotis patagonum) are common open-steppe species. Armadillos, mountain viscachas, and Andean foxes (Lycalopex culpaeus) are frequently encountered. The volcanic terrain supports unique lizard species including the Patagonian tree iguana. Migratory birds use the reserve seasonally, with various raptor species overwintering in the region.

Vegetation in La Payunia reflects the harsh volcanic substrate and arid Patagonian climate. The dominant plant community is a sparse thorn-steppe with characteristic shrubs including jarilla (Larrea divaricata), neneo (Mulinum spinosum), and various cushion plants adapted to rocky, nutrient-poor volcanic soils. On older lava flows, slow-colonizing pioneer plants including saxicolous lichens and drought-resistant herbs gradually establish in sheltered cracks and depressions. The slightly more productive grasslands between lava fields support bunchgrasses (Stipa and Festuca species) that provide grazing for guanacos. In the few stream corridors crossing the reserve, more diverse riparian vegetation provides habitat for wildlife not found on the open steppe.

La Payunia sits atop one of the world's most remarkable Quaternary volcanic fields, with over 800 volcanic cones of varying ages and types scattered across the plateau. The region represents the back-arc volcanic zone behind the main Andean volcanic chain, where mantle-derived magmas reach the surface through extensional faults rather than subduction-related processes. Lava flows ranging from relatively recent (a few thousand years old) to older Pleistocene eruptions create a patchwork of surfaces at various stages of soil development and vegetation colonization. The youngest lava flows retain razor-sharp aa and pahoehoe surfaces with little biological modification. Payún Matrú, an active stratovolcano rising to 3,680 m, and Payún Liso (3,510 m) are the dominant volcanic edifices in the reserve.

La Payunia's climate is semi-arid to arid, influenced by the rain shadow effect of the Andes and the cold Patagonian air masses from the south. Annual precipitation is low, averaging 150–250 mm concentrated in winter months as snowfall at higher elevations. Summers (November–March) are warm with temperatures reaching 25–30°C in the valleys, while winters bring cold nights regularly below -10°C and frequent snowstorms. The region is extremely windy, with sustained Patagonian westerly winds scouring the open steppe throughout the year and gusts exceeding 100 km/h during cold fronts. Visibility can be exceptional on clear days, with the volcanic cones visible for enormous distances across the flat terrain. Thunderstorms occur occasionally in summer.

Archaeological evidence indicates human presence in the La Payunia region for at least 8,000 years, with hunter-gatherer groups exploiting the abundant guanaco herds of the volcanic steppe. Rock art sites within and near the reserve document Pehuenche and other indigenous Andean groups who used the area seasonally. Spanish colonization brought cattle and horse ranching into the Mendoza interior from the 17th century, with the volcanic plateau used as extensive summer grazing range. The Araucanization of the Patagonian peoples in the 18th–19th centuries brought Mapuche cultural influences into the region. The Argentine state incorporated the territory after the Conquest of the Desert military campaigns of the 1870s–1880s, dispossessing indigenous peoples from their traditional territories.

La Payunia was designated as a Provincial Reserve by the Mendoza provincial government, reflecting recognition of both its exceptional geological heritage and its wildlife values, particularly the large guanaco population. Management is the responsibility of the Mendoza Department of Natural Resources. The reserve's designation came in part in response to hunting pressure on guanacos, which had significantly reduced populations in prior decades. Ongoing management priorities include controlling illegal hunting, managing water sources for wildlife, and balancing limited livestock grazing with wildlife habitat needs. Research partnerships with Argentine and international universities have produced studies on volcanic geology, guanaco population dynamics, and ecosystem ecology that inform management decisions.

The landscape itself is the primary attraction: driving or hiking across the basaltic lava fields surrounded by hundreds of volcanic cones creates an otherworldly experience unlike anywhere else in South America. Payún Matrú volcano can be ascended via a long day hike offering panoramic views of the volcanic field and Andes. Guanaco herds are reliably encountered, with large aggregations particularly impressive during winter and spring migrations. The reserve is typically visited on a day trip from Malargüe, the nearest town, with 4x4 vehicle tours departing early morning. Sunset over the volcanic cones is particularly dramatic. Birdwatching for condors and open-country steppe species is excellent throughout the reserve.

La Payunia is accessed from Malargüe, a small city 220 km south of Mendoza city, reachable by paved Highway 40. Malargüe has hotels, restaurants, and a tourist information office. The reserve entrance requires a permit obtained in Malargüe, and 4x4 vehicles are mandatory as there are no paved roads within the reserve. Day tours from Malargüe are available through local operators and are recommended for visitors without their own 4x4. There are no permanent facilities within the reserve — no visitor center, ranger station, or formal campsites. Visitors must carry all food, water, and fuel. The reserve is open year-round but winter access (June–September) may be limited by snow. The best wildlife viewing is in spring (October–November) and winter.

Illegal hunting of guanacos for meat and hides has historically been a major threat, reducing populations significantly before protection was formalized. Anti-poaching enforcement and community engagement have helped stabilize numbers. Uncontrolled livestock grazing competes with guanacos for limited forage and water sources, and reducing cattle numbers to sustainable levels remains an ongoing management objective. Off-road vehicle damage to the fragile volcanic surface and pioneer plant communities is a concern as recreational tourism grows. Climate change is expected to intensify aridity and reduce water availability in this already water-stressed ecosystem. The reserve's geology is of international scientific importance, and monitoring of volcanic activity provides baseline data for regional hazard assessment.