Landscapes with Araucaria in South Americaevidence for a cultural dimension

The forests that the Spanish and Portuguese colonizers called wilderness were gardens. Not metaphorically — literally shaped, seeded, and tended by human hands for thousands of years. Let that sit for a moment. Then consider this: Reis, Ladio, and Peroni spent years compiling the ecological and ethnobotanical evidence, and what they found rewrites the story of one of South America's most iconic trees. There are two trees at the center of this story. Araucaria araucana — the pehuén — grows in the southern Andes, mostly between 37 and 42 degrees south, straddling the Argentine-Chilean border at elevations between roughly 900 and 1,800 meters. Its historical range covered about 5,000 square kilometers. Araucaria angustifolia — the Brazilian pine — occupied a far larger territory: the highland forests of Rio Grande do Sul, Santa Catarina, and Paraná in southern Brazil, across an estimated 200,000 square kilometers. Two species, separated by geography, but linked by the same dynamic — a deep, mutually shaping relationship with human communities. Araucaria araucana belongs, above all, to the Mapuche-Pehuenche. Their very name tells you: pehuén is the tree, Pehuenche means the pehuén people. Araucaria angustifolia was central to the Kaingang and other Jê-speaking groups in southern Brazil, who managed pine forests with strict territorial rules that early historical accounts describe in striking detail. Both forests are now drastically reduced. Araucaria araucana remnants cover roughly half their pre-contact area. Araucaria angustifolia has fared far worse — current remnants represent only 5 to 12 percent of the original range, and the conservation units protecting that species collectively cover just 0.62 percent of its former distribution. Those numbers matter. They frame everything else. The question Reis, Ladio, and Peroni ask is whether this contraction happened to the forests or whether, in some sense, the forests grew because of the people. To answer it, they pull together three independent lines of evidence: pollen records, archaeology, and genetics. The pollen record — palynology — shows when these forests expanded. For Araucaria araucana, the distribution reached its Holocene maximum around 3,000 years before present. For Araucaria angustifolia, the expansion peak falls later, between roughly 1,500 and 800 years before present. Now here is the key: archaeology places humans in those landscapes before or at the same time as those expansion peaks. Human occupations in Araucaria araucana territory are documented at about 4,000 years before present. In Araucaria angustifolia country, occupations date to around 2,500 years before present. The mapped distribution of archaeological artifacts and pit houses associated with pre-Columbian Kaingang groups matches the modern forest distribution. That is not a coincidence the authors take lightly. Then there is the ecological argument. Both Araucaria species are primarily gravity-dispersed — their heavy seeds fall and do not travel far on their own. Yet the forests expanded over large areas during exactly the period humans were present and moving through them. Palynological work linking increased fire and grassland formation with the Araucaria angustifolia expansion is consistent with anthropogenic burning, and fire creates the open microsites young Araucaria need to establish. The genetic evidence adds a third thread. Across multiple studies of both species, there is a consistent lack of isolation by distance — meaning genetic similarity does not simply decrease as you move farther apart, as you would expect if seeds spread gradually outward on their own. Several populations also show elevated fixation indices, a signature compatible with founding events: new populations started by a small number of individuals. Reis, Ladio, and Peroni interpret these patterns as consistent with human transport and planting — people carrying seeds across long distances and establishing new stands, leaving behind genetic fingerprints of those journeys. Which brings us to what the people were actually doing with these seeds, because the cultural practices are extraordinary in their detail and organization. The large, nut-like piñones of both Araucaria species were not occasional snacks. They were staples, and the economies built around them were elaborate. For the Mapuche-Pehuenche, gathering has its own word — ngümitun, or piñoneo — and its own season: from February through April, when mature piñones fall. Families practiced veranada, seasonal movement into the pehuén forests in summer, establishing semipermanent gathering sites before hauling seeds back to winter dwellings. Ladio and Lozada documented Mapuche families in Neuquén routinely traveling more than 100 kilometers and carrying more than 100 kilograms of seeds per trip. Those seeds were processed into roasted foods, flour, bread, and a fermented beverage called mudai, or stored in buried underground caches where they stayed viable for months — and sometimes germinated in place. The Kaingang organized pinhão harvests with even more visible social structure. A 19th-century account cited by Reis and colleagues describes family-line administration of gathering territories, chiefs who guaranteed equitable sharing, and consequences for territorial violation that ranged from severe punishment to outright war. Men felled cones; women collected seeds. Whole cones were transported and stored in humid environments — streams and riverbeds — to preserve them for later processing into flour. What did all this human activity do to the forest? More than anyone had previously understood. Consider the seed productivity numbers: Araucaria araucana trees in good years produce 45 to 50 cones each, and exceptional trees over 300. Productivity per hectare can exceed 600 kilograms. When families are transporting more than 100 kilograms of seeds per trip — dropping some along the trail, storing others in buried caches that germinate in place, intentionally planting seeds during gathering trips — they become, functionally, dispersal agents at a scale the tree's own gravity-based dispersal cannot match. Ethnographic sources cited by Herrmann describe deliberate planting at gathering sites and protective behaviors: leaving desirable trees standing during clearing, marking valued individuals, enforcing harvesting rules that left enough seed to maintain future yields. This is where the story takes its sharpest turn. If human disturbance — fire, seed transport, open clearings — was integral to how these forests established and regenerated, then removing humans from the equation should have consequences. And it does. Reis, Ladio, and Peroni document regeneration deficits inside conservation units across the range of both species. Multiple studies find that young Araucaria are failing to recruit in protected areas, and in several cases, the principal explanation is the absence of the disturbances that create open microsites for seedlings. Protection, as conventionally practiced, has removed the very processes the forests evolved alongside. The irony is exact: a conservation model built on keeping people out may be quietly dismantling the conditions that made these forests possible in the first place. Reis, Ladio, and Peroni are careful here. Traditional gathering methods, when maintained, do not harm regeneration — several studies cited find no negative regeneration effect from human piñón collection. What does harm regeneration is livestock. The problem is not human use per se; it is the removal of the specific human practices that benefited the forest, while sometimes substituting damaging land uses in their place. The policy prescription that follows from this evidence is direct. Conservation of Araucaria landscapes should be participatory — a formal partnership between conservation biologists and traditional communities, not a replacement of one by the other. The research agenda needs to quantify specific traditional management practices: tolerance of individual trees, enhancement, protection, seed cultivation, and transplantation. The paper calls explicitly for evaluating the domestication hypothesis — the possibility that these trees, over millennia of human selection and propagation, were partially domesticated in ways that shaped their current genetic and ecological character. The practical upshot is both modest and significant. Protecting Araucaria means protecting the people and practices that kept them. Where exclusion is the default, forests survive in some form, but they are not maintained on the same criteria that made them nutritious, resilient, and genetically diverse cultural groves. What Reis, Ladio, and Peroni leave us with is an image worth carrying: a forest that persists because successive generations chose to gather, plant, bury, and defend its seeds — a landscape literally sustained by people choosing it, year after year. Take that away, and you haven't protected the forest. You've just slowed its unraveling. This lecture was created by ennepō. Go to https://ennepo.ai to Discover, Create and Follow the latest research in your field. Read when you can. Listen when you want to.