Extreme forestry: what does bungee jumping say about parasitic vines? (Biomechanics).

Publication: Natural History

Publication Date: 01-JUL-03

Bookmark this article Print this article Link to this article Email this article Digg It! Add to del.icio.us RSS

COPYRIGHT 2003 Natural History Magazine, Inc.

It is May, time for naghol--a centuries-old fertility ritual practiced on Pentecost Island in Vanuatu, in the South Pacific. The participants--the island's young men--perform land dives to obtain a blessing for their people's crops. As a crowd of islanders watches, each young participant scales a rickety scaffold of branches to a platform some seventy feet above the tilled earth. The diver pauses for a moment, then leans forward and plunges headfirst off the platform, trailing vines tied to his ankles. If he has chosen the vines well, they will pull taut and stretch like a natural bungee cord, just enough to gently arrest his fall. If he has chosen poorly, he may slam into the ground or be yanked back against the platform.

The success of such derring-do evidently depends on the material properties of lianas, or woody vines. But how can woody vines stretch like oversize rubber bands? To answer that question, let's go to the...

Read the full article for free courtesy of your local library.