National Geographic : 2005 Mar
Perhaps you've hiked past them in parks, or seen them by the side of the road, wrestling honey suckle or Himalayan blackberry. What may look like a hopeless battle and a lousy way to spend a Sunday yields results. Volunteers battle Scotch broom in Washington's Olympic Peninsula region most every Tuesday, rain or shine; there's still Scotch broom, but no longer so much of it as to bar the flight of prairie butterflies. In the Waikamoi Preserve on Maui, Nature Conser vancy volunteers have weeded kahili ginger from the forest floor one Saturday a month, every month, for 14 years. As a result of their work, rare native ferns and mosses are still luxuriant on the ground there. In the grandest weed pulling project of all, South Africa employs more than 20,000 people felling and uprooting water hogging invasive trees. It's a program that has restored water to streambeds-and self-respect to impoverished, long-out-of-work citizens, many of them women. It's been 15 years now since the U.S. entered the period Jim Carlton likes to call A.Z.M.-after zebra mussels. At a shocking cost to economies and to nature, we've learned what damage invasives can do. Some of it is permanent. No amount of ballast water exchange is going to eradicate zebra mussels from the Great Lakes. No fumigating of shipping pallets will reinstate the American chestnut, king of North America's eastern forests, felled by an invasive fungus. Many ecosystems are simply changed beyond recognition; for them, there's no going back. But what we still have is infinitely precious. To sit by and watch it destroyed would be worse than foolish; future generations will call it unforgivable. 0 JOIN DETECTIVES in tracking down alien species in Invaders, the first episode of NationalGeographic's Strange Days on Planet Earth, an award-winning four-part series pre miering on PBS Wednesdays, April 20 and 27.