Mother Earth can really bring out the stars. Leonardo DiCaprio, Melanie Griffith, Ted Danson, Edward James Olmos, Ed Begley Jr., James Taylor, the Beach Boys, Carole King and many more are expected to grace the Mall in Washington, D.C., on April 22 at the main event celebrating the 30th anniversary of Earth Day. Leo, who has taped several radio public service announcements scheduled to air that day, is the chairman of the big D.C. ecological event, reports Variety columnist Army Archerd. Also on April 22, CNN will air a special on global warming to be hosted by Jane Fonda. More than 170 countries are expected to participate in Earth Day 2000, which will feature more than 4,000 events that focus on the problem of global warming and the benefits of clean, natural energy.