Fifty years ago this week, President Lyndon Johnson signed the Wilderness Act. The legislation designated over nine million acres of federal land as protected ground, “an area where the earth and its community of life are untrammeled by man, where man himself is a visitor who does not remain.” Greg Aplet, senior scientist at the Wilderness Society, says that wild spaces are important for reasons beyond landscape postcards—they have implications for species habitat, global warming, and more.