On cleared Chaco pasture, a veterinarian makes room for the tree that once fed a region

On the Don Nicanor farm in Argentina's Santa Fe province, veterinarian Mario Oertlinger opened worn-out cattle land to native trees. He is one of several ranchers in the Gran Chaco Seco who did so, and together they now host more than 100,000 young trees on 367.2 hectares. Most are algarrobo blanco, a tree that gives shade to cattle and helps rebuild the soil beneath them.

Mario Oertlinger watches the land as a veterinarian. His concern is animal welfare, and in the Chaco that starts with the heat. Cattle grazing on open, cleared land have nowhere to escape the sun. The returning trees, he said, change the conditions the animals live in.

His neighbour in Santa Fe, Mariano Fiori, is looking further down. He wants the soil under the new canopy to recover its biodiversity. The tree he is relying on suits the task. The algarrobo blanco, now classified as Neltuma alba, is a legume. Bacteria in its root nodules fix nitrogen and return nutrients to poor ground. It also tolerates drought, which matters in the dry western Chaco. About 80 per cent of the seedlings planted between spring 2024 and spring 2025 were algarrobo.

The work covered farms in Santa Fe, Santiago del Estero and Chaco provinces. Foresters from Optimizar Forestal, led locally by Luis Arguello Pitt, directed the planting. Their specialised crews could plant up to 2,500 trees a day. The Universidad Nacional de Santiago del Estero raised 20,000 more seedlings of other native species in its nursery, and botanist Sandra Bravo ran education sessions with nearby schools.

This land has been stripped before. From the early twentieth century, the British company La Forestal felled quebracho trees across northern Santa Fe for their tannin, which was used to process leather. At its height the company controlled more than 2 million hectares. When it pulled out in the 1950s and 1960s, the towns it had built lost their main employer. In recent decades, soy fields and cattle pasture have driven most of the clearing.

The algarrobo is older than all of that. For centuries the Wichí, Qom and Moqoit peoples of the Gran Chaco have ground its pods into flour, fermented them into a drink and boiled them into syrup. In Quechua it is called taku: the tree.

Nativas, the organisation monitoring the plots, has recorded a survival rate of 90 per cent and replaces the trees that fail. The Nature Conservancy Argentina coordinated the coalition with support from John Deere Argentina. Its aim is to show that cattle ranching and forest conservation can share the same land instead of competing for it.

That idea is now spreading from farm to farm. Antonella Fernández of Nativas said that neighbouring landowners have seen young algarrobo taking hold on land once cleared for grazing. Now they are asking to join.