San Antonio

San Antonio Natural Reserve (Reserva Natural Estricta San Antonio) in Misiones Province, northeastern Argentina, protects approximately 480 hectares of Atlantic Forest—the most biodiverse and most threatened forest in the Western Hemisphere. ^[1] Located near the town of San Antonio in the General Manuel Belgrano Department, adjacent to the Argentine-Brazilian border, the reserve was established in 1990 through Decree No. 2149/90. ^[2] It protects a fragment of the Selva Misionera, the southernmost extension of the Atlantic Forest, and is notable as the only national-level protected area in Argentina containing Araucaria angustifolia (Paraná pine) forest, of which fewer than 1,000–2,000 hectares survive in Misiones today. Though small, the reserve serves as a critical refuge for this critically endangered conifer and the wildlife that depends on it.

Despite its small size, San Antonio harbors an impressive array of Atlantic Forest wildlife. The reserve protects habitat for the endangered vinaceous-breasted parrot (Amazona vinacea) and the red-tailed amazon (Amazona pretrei), both reliant on Araucaria seeds. ^[1] The bird diversity is extraordinary—over 450 species have been recorded in the broader Misiones Atlantic Forest, including the harpy eagle and black-fronted piping-guan. Mammals including tapirs and giant anteaters are present. Bats, frogs, and reptiles show very high species richness. The reserve connects to the broader conservation network in northern Misiones, collectively protecting one of the largest Atlantic Forest blocks in Argentina.

The reserve protects the only Araucaria angustifolia (Paraná pine or pino paraná) forest within Argentina's national protected area system. ^[1] This critically endangered conifer—declared a Provincial Natural Monument by Misiones—reaches heights exceeding 30 meters with a distinctive umbrella-shaped crown; more than 800 specimens of good size have been identified in the reserve. The forest canopy also includes guatambú blanco (Balfourodendron riedelianum), lapacho negro (Handroanthus heptaphyllus), and native yerba mate. The understory is rich in tree ferns, palms, bamboos, bromeliads, and orchids. In 1960 some 210,000 hectares of Araucaria forest existed in Misiones; today fewer than 1,000–2,000 hectares remain, making the reserve a critical conservation stronghold.

The Misiones Province geology is characterized by extensive basaltic plateaus formed by the massive Paraná Large Igneous Province volcanic event approximately 130 million years ago during the Early Cretaceous, one of the largest flood basalt eruptions in Earth's history. ^[1] The deep red lateritic soils (called 'tierra colorada') derived from basalt weathering are a signature feature of the region. These iron-rich soils are highly fertile, explaining the high agricultural pressure on surrounding lands. The reserve, located at approximately 500 meters above sea level, presents distinct forest structure compared to lowland areas of Misiones, with high-elevation Atlantic Forest communities differing from those in the Iguazú lowlands. The terrain consists of gently rolling hills and steep stream valleys carved into the basalt.

Misiones Province has a humid subtropical climate with no dry season. Annual rainfall is 1,500–2,000 mm, distributed throughout the year with highest rainfall in October–November and February–March. The reserve sits at approximately 500 meters above sea level in the General Manuel Belgrano Department, giving it slightly cooler temperatures than the Iguazú lowlands. Temperature averages 20–22°C annually. Summer temperatures reach 30–35°C. Winters are mild, rarely dropping below 10°C. Frost is exceptional and occurs only in unusual cold-air incursions. The humid conditions support the dense forest growth typical of the Selva Paranense ecoregion.

The Misiones forest was inhabited by the Mbyá Guaraní people, a branch of the Guaraní nation, for centuries before European contact. Jesuit missionaries established reducciones (mission settlements) in Misiones in the 17th century, converting and settling indigenous communities in large organized towns. The Jesuit missions were expelled in 1767, and the mission settlements declined. The area was settled by European immigrants—particularly Ukrainians, Poles, and Germans—in the late 19th and early 20th centuries, who cleared vast tracts of forest for agriculture. The General Manuel Belgrano Department, where the reserve is located, takes its name from the Argentine national hero and military general.

San Antonio Natural Reserve was established in 1990 under Decree No. 2149/90 with a strict protection category that permits no human use except scientific research and monitoring. ^[1] The lands previously formed part of the General Manuel Belgrano Forestry Station, where the Argentine National Forestry Institute conducted experiments with conifers and eucalyptus while preserving a sector of native forest; when the Forestry Institute was dissolved, the Administración de Parques Nacionales assumed management of the land. The small size of the reserve—only 480 hectares—reflects the limited remaining undisturbed high-elevation forest available for protection in Misiones, which has lost over 80% of its original forest cover. The reserve is critical as the only unit in Argentina's national protected area system containing Araucaria angustifolia forest.

Access to San Antonio is restricted due to its strict nature reserve status, and visits require advance authorization from the APN. ^[1] Researchers and conservation professionals are the primary visitors. The reserve's Araucaria forest and associated biodiversity make it a valuable site for botanical and herpetological research. The surrounding area near San Antonio town has less-restricted forest access points. The nearby Urugua-í Provincial Park offers more accessible Atlantic Forest experiences, and the combination of reserves in the northern Misiones creates one of Argentina's premier wildlife corridors.

San Antonio has minimal visitor infrastructure due to its strict reserve status. The ranger station is the only facility. General visitors should contact the APN for access permits well in advance; the reserve is not open to the general public. ^[1] The town of San Antonio, near the border crossing to Brazil, provides basic accommodation and services. The reserve is located in the General Manuel Belgrano Department, reached from Bernardo de Irigoyen or San Antonio via Route 14. Most nature tourism in the area focuses on the more accessible Urugua-í Provincial Park to the south or the internationally famous Iguazú Falls.

The Atlantic Forest is considered one of the world's most endangered tropical forests, having lost over 85% of its original coverage. San Antonio's primary conservation value lies in protecting the last nationally managed stand of Araucaria angustifolia forest in Argentina, a formation that has declined from 210,000 hectares in Misiones in 1960 to fewer than 1,000–2,000 hectares today. ^[1] The small size of the reserve means it requires functional connectivity with surrounding forest fragments. Illegal logging and poaching remain persistent threats at the forest margins. Pine plantations and agricultural lands surrounding the reserve create a fragmented landscape. Joint conservation efforts between Argentina, Brazil, and Paraguay through the Trinational Atlantic Forest Corridor initiative aim to reconnect forest fragments across national boundaries.