High-altitude engineers
In the Bayan Kara Mountains, a range that separates the great drainage basins of the Yellow and Yangtze rivers, lies the Sanjiangyuan National Park. This park, with an average elevation over 4,700 meters, is a vast area of alpine meadows and wetlands. Here, a small, unassuming mammal, the Plateau Pika (Ochotona curzoniae), shapes the entire ecosystem. Often living at altitudes between 3,100 and 5,000 meters, these relatives of rabbits are keystone species.
For decades, pikas were viewed as pests, blamed for rangeland degradation, and subjected to widespread poisoning campaigns that began in 1958. Scientific studies now show a different picture. Pika burrowing activity aerates the ground and increases water infiltration, which can reduce overland flow and minimize soil erosion. Their digging creates patches of bare soil that, while seemingly destructive, actually increase plant biodiversity. These disturbed areas provide new ground for different plant species to colonize, leading to a total species richness 1.3 to 2.5 times higher than in undisturbed patches. The pikas' burrowing transfers between 1 and 5 tons of soil per hectare to the surface, mixing soil layers and affecting nutrient cycles.