Video The ex-poachers saving big cats in Russia

Larger green spaces may be critical to a city, as they can support more complete ecosystems. In contrast to smaller "parklets," large parks paired with high-density neighborhoods allow for healthier cities.

Poor neighborhoods in the United States lack quality play spaces for children, also known as play deserts. An organization is enabling communities across the nation to build their own playground.

Great minds from Plato to Piaget have recognized the importance of play in healthy child development, but with bullying becoming more prevalent on school playgrounds and increased pressure to maximize school hours to boost performance on standardized tests, schools are struggling to implement meaningful recess. Playworks and other similar non-profit groups provide coaching for adults on how to help structure children's playtime to be healthy, productive, and enjoyable, while allowing children to explore on their own and develop positive relationships.

Invasive weeds are ruining the habitat of New York's wild bog turtles. In Hudson River Valley, domestic goats and cows are being used to save bog turtles by grazing on this foreign weed. So far, the plan seems to be working as the turtles have shown signs of not just returning but also laying eggs in the area.

Growing wolf populations in Wyoming are forcing the U.S. Fish and Wildlife Service to make hard decisions about culling the endangered species in order to preserve local wildlife and livestock.

The fate of the Southeast's longleaf pine forests, and the endangered woodpeckers that depend on them, is in jeopardy. Fort Bragg, a station of the US military, is trying to save their local environment.

Obesity is at an all-time high in the United States, and is hard to combat. But urban obesity can be countered with inviting streets to stroll, dramatic staircases to climb, parks to exercise in - it’s called “active design.”

There are only five northern white rhinos left in existence - all in captivity and unable to breed. Researchers work to identify the most valuable solution to rhino poaching in order to prevent the animal from going extinct.

A robust population of grizzly bears can be an indicator of healthy land; however, the bears also can destroy grain bins, consume vegetation, and kill livestock. Ranchers work with the Canadian government and local conservation groups to protect their resources with bear-proof grain bins and electric fences.

Despite strong evidence that school-based physical activity improves children’s cognitive skills, concentration, and behavior, schools under pressure to produce quantitative results and decrease bullying have drastically cut back on recess in recent years. An Oakland-based nonprofit organization called Playworks is working to make healthy play accessible for more children and show schools how productive recess can be to the whole academic world.