Life has adapted to our changing planet for over 3 billion years. The staggering diversity of life on Earth that you see today is less than 1% of all the organisms that ever lived. Fossils provide evidence of a great variety of other species that existed in the past. Species that have no surviving members are said to be extinct.

If extinction is a natural process, then why should we worry? Extinction leads to a loss of biodiversity. The activities of people increase both the rate and the number of extinctions. When humans colonize new land, they bring with them alien and often invasive species. Without natural predators to check their populations, they quickly out-match the endemic species in the competition for resources.

The loss of even one species may have an impact on human survival. Think about extinction in terms of what might be lost to us. The source of many drugs used in medical and veterinary sciences come from plants. Many more chemical compounds in common fungi or plants could become new weapons against disease. There are more than 75,000 edible plant species in the world, but only about 150 species are grown as crops by farmers. Other plants provide timber, fibers, and energy.

The greater the biodiversity in an ecosystem, the more complex the food web can be. In a complex food web, if one species dies off, other links in the web will keep the system from collapsing. That makes the world a more habitable place for members of the ecological community—including us.

Large ecosystems with a variety of habitats support the greatest biodiversity. When an ecosystem is cut into smaller pieces it is called habitat fragmentation. That causes the system to be less stable. Island ecosystems are fragile and react to even small changes because they are isolated by the bodies of water that surround them. Land ecosystems can also be fragmented. Mountains, rivers, and even structures like highways can cut off habitats, turning them into “islands.”

Ecological corridors can connect fragmented habitats. For example, the Mountains to Sound Corridor in the state of Washington not only provides recreation for people, but also protects wildlife habitats and riparian zones by interconnection forests, farms, rivers and trails. The largest wildlife corridor in the eastern U.S. is the Pinhook Swamp Project. It connects Georgia’s Okefenokee National Wildlife Refuge with Florida’s Osceola National Forest. This corridor protects critical black bear habitat and water resources for the city of Jacksonville, Florida.

Corridors help protect biodiversity and improve the over-all health of ecosystems by increasing the amount of habitat individuals have to roam. This also helps protect migratory routes of animals by providing a safe-zone for them to move from one habitat to another. Migration is the seasonal or periodic movement of animals to find food, water, shelter, or a mate. Some migrations cover thousands of kilometers, from one hemisphere into the other. Using laws in a measured and considered way to protect the migratory routes of animals often involves international treaties.