John Muir called it the "Range of Light, the most divinely beautiful of all the mountain chains I’ve ever seen." The Sierra Nevada—a single unbroken mountain range stretching north to south over four hundred miles, best understood as a single ecosystem but embracing a number of environmental communities—has been the site of human activity for millennia. From the efforts of ancient Native Americans to encourage game animals by burning brush to create meadows to the burgeoning resort and res...