Since 1996, Australia has designated the last Sunday in July as National Tree Day, when volunteers plant thousands of native trees and shrubs in their local areas. The annual event is planned by Planet Ark, sponsored by Toyota and the AMP Foundation and endorsed by sexy gardener/beefcake Jamie Durie and not-so-beefy Olivia Newton-John. This year's National Tree Day will happen on July 27, with the accompanying Schools Tree Day taking place on July 25, with 12 additional planting dates occurring throughout the year.

The goal of this event is to plant trees and shrubs native to the country that will provide food and shelter to Australian wildlife, as well as increasing native biodiversity. In the past year, more than 220,000 children participated in the initiative, and to date over 11.5 million trees and shrubs have been planted by more than 1.5 million volunteers since the first 1996 planting.

Watch the clip to hear Jamie (who is unfortunately fully-clothed this time) and Olivia talk about National Tree Day, and hit the jump to visit the official event site, where you'll find teacher resources, kid-friendly activities and to learn how you can get involved (the clip is from 2006 by the way, so ignore Jamie when he mentions that National Tree Day is on July 30).

» National Tree Day (Official Site)