Denver is built on shortgrass prairie, which is “one of the most endangered ecosystems in the world,” says Jeff Su, executive director of the Plains Conservation Center. Only 3.4 percent of the world’s limited temperate grasslands remains protected. The center has two sites that sit on—and work to preserve—11,000 acres of that safeguarded land. The main site, outside Aurora, has an education center and access to more than five miles of trails where wildlife abound. (The second spot is south of Strasburg.) Help continue the center’s work at Hops for Habitat on July 19: The annual fund-raiser includes bottomless brews from 15 local breweries, live music, and food trucks. Or: Volunteer as a school group leader to educate the next generation.