Losing one or two species may affect the entire web, including us. Also at risk are the farmers who depend on the insect to pollinate the crops, and the local economies that depend on successful farmers. A greater variety of life also helps nature adapt to an unpredictable world. Scientists have learned that the greater the variety of species in a biological community, the better the ecosystem can recover after droughts, ice storms or other calamities, or adjust to man-made changes such as global warming or air pollution. Forests clean the air and turn the carbon dioxide we exhale into oxygen we breathe.
Wetlands purify water and act as a sponge, preventing floods.
Wild plants and animals provide direct benefits, too. One third of the country's crops depend on insects for natural pollination. Many of our important drugs, such as cancer treating taxol, come from plants. While each of the reserves protects several different habitat types, there remain many habitat types that are unprotected. The challenge for the next few years is to complete the system.