It"s American Wetlands Month, a time to celebrate swamps, marshes, bogs, and other types of these important ecosystems. Wetlands play a vital role in storing carbon, improving water quality, and serving as habitat for many endangered plants and animals, including American crocodiles and whooping cranes. And yet, wetlands are threatened. Over the centuries, they have been drained to provide land for farming, industry, and housing. Pollution and invasive plants pose further threats. Since the late 1700s, more than half of the 221 million acres of wetlands that once existed in the 48 contiguous states have disappeared.