Earth Day Network is enlisting groups in 15 countries to plant 1 million trees this year with "Avatar" movie director James Cameron and Twentieth Century Fox.
Cameron planted the first of 1 million trees in April in Brazil.
In the U.S., trees will be planted in New York, San Francisco and Los Angeles to improve air quality and urban animal habitats.
Tree plantings in such places as Mexico, Canada and Spain will be focused on reforestation of depleted areas.
