For many reindeer to survive in the wild, this lichen is necessary. Reindeer live in the Arctic tundra (a frigid treeless plain) and the northern boreal woodlands that border the tundra.

They have special bacteria in their gut to help them digest it and are the only species to use lichen as a food source. There aren't many denning sites in the tundra's permafrost for predators ...

More: ・Historically: The New York Times explains that for millennia, the moss, lichens, and other vegetation of the tundra have taken in carbon dioxide and stored it, as all plants do.