American prairies were once home to as many as 60 million bison. But when ranching and agriculture displaced elk and bison from the prairies, America’s grasslands all but disappeared. Now, the Nature Conservancy manages the largest remaining protected tract of tallgrass prairie in the entire world, the Joseph H. Williams Tallgrass Prairie Preserve in northeastern Oklahoma.

This 40,000-acre expanse is much more than grass. It is a biologically rich habitat that harbors a diverse collection of plant and animal species—more than 750 species of flora and 80 different mammals. This prairie is also a vital component in nature’s fight against climate change. The key to keeping the prairie healthy? Bison.

The Nature Conservancy reintroduced 300 bison to this prairie in 1993, and the herd has grown to more than 2,000 animals today. They graze on the majority of the preserve, playing an important part in enhancing the prairies. Combined with a method of land management known as patch burning—preserve managers torch about a third of the acreage every spring, summer, and fall, mimicking ancient seasons of fire—the tallgrass prairie is thriving.

Florida’s native crocodiles have found an unexpected sanctuary in the cooling canals at Turkey Point Nuclear Power Plant. This fortunate happenstance, along with tireless conservation efforts, are helping these once endangered predators make a remarkable comeback.

The Everglades is a water world — It’s the widest and slowest river in the United States. But in the heart of this great water body exist secret islands that have outsize importance for the cultural heritage of a people and for the biodiversity of this important wetland. Thousands of these tree islands dot the Everglades. For generations, the Miccosukee people have called these islands home. And they’ve long understood that the islands are a giver of life in this unforgiving environment. The islands are some of the only dry land around and harbor a surprising diversity of plant and animal life, including: coyotes, bobcat, bear, and even the Florida panther. But among the scientific establishment, the islands are little understood. Researchers from the Miccosukee tribe are working to understand how animals use the islands and what role they play in the larger Everglades ecosystem. With the islands under threat from outside forces, their studies have taken on increased urgency. What they’re finding could be key to preserving the Miccosukee culture and the balance of life in this great river.