Governments around the world conserve plants and animals in part by setting aside land. Whether as wilderness reserves or as resource management zones that allow industrial activities such as logging, 17.4% of the planet's land offers some measure of protection. These protected areas overlap with on e-fifth, on average, of the range of Earth's terrestrial mammals. But beneath these parched deserts, dark forests, and rolling grasslands is an invisible world that keeps these aboveground places healthy. And we're not protecting that world much at all. ...read more read less