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When glaciers melt, they leave behind infertile (贫瘠的) landscapes. But a new study found that within just three years, such exposed land was restored by llamas (美洲驼), whose activity enriched the soil and promoted plant growth. By the foot of Peru’s melting Uruashraju glacier, researchers partnered with local farmers to farm llamas on four specific plots. For three days a month from 2019 to 2022, the llamas grazed (吃青草) the plots, fertilizing them with waste and spreading seeds from droppings.

As is the case worldwide, glaciers are disappearing in Peru’s Cordillera Blanca mountains at an alarming rate. And as the ice melts, nearby ecosystems wither: They lose access to summertime supplies of freshwater and sometimes encounter harmful acidic minerals in rocks once covered by the glaciers.

Llamas may help count er some of these effects. Their transformation of the land, as seen in the new study, could reduce rock weathering and help the soil hold onto more dampness, thus limiting the acidic runoff that can poison farmers’ crops. Such pollution is one reason why local farmers partnered with the researchers. The animals’ behavior could one day even generate new grasslands as soil quality improves.

The idea that animal grazing may positively impact a landscape is not new. Nor is rewilding, the push to bring key species back to their native ecosystems, unique to the Cordillera Blanca mountains. In Finland, for example, the Indigenous Sami are working to reintroduce reindeer in deforested land, potentially restoring it. But the size and speed of the changes the llamas helped bring about surprised the researchers. From 2021 to 2022, the average amount of plant cover in the llama plots grew from about 9 percent to nearly 14 percent—faster than it did in four control plots. The research underscores the valuable roles animals play in shaping landscapes, says ecologist Kelsey Reider of James Madison University in Harrisonburg, Va., “The animals themselves are doing a lot.”