Zebras give life to the Namib desert by rolling around

摘要

ROLLING on the ground seems to be essential to life - at least in Africa's Namib desert, where zebras bathe in dust, creating pits that promote biodiversity. The Namib desert is a vast stretch of dunes and mountains along the coasts of Angola, Namibia and South Africa. It is the world's oldest desert and one of the driest. Despite this extreme aridity, many animals and plants have adapted to survive, including the Hartmann's mountain zebra (Equus zebra hartmannae). Herds live on the mountainous desert edge, migrating with rainfall. The zebras often roll in the dusty ground to groom and get rid of parasites. As part of this process, they hoof out large stones and displace the soil, making comfortable spots in which they rest and leave dung. These pits can reach up to 30 centimetres deep and can last for years. Thomas Wagner at the Technical University of Munich, Germany, wondered if there were ecological benefits to this accidental landscaping. Over five consecutive rainy seasons, Wagner and his team calculated vegetation cover from drone images in more than 650 rolling pits, tracking the greening and wilting of the landscape following rains. They sampled soil and plants in 16 of the pits, using surrounding grassland as controls.