Timber industry goes underwater

As the world's thirst for wood grows and the resulting deforestation contributes to a wide range of environmental problems, one enterprising group has gone to a surprising location to search for more sustainable wood supplies--under the water.

A great amount of timber sank during log drives or was flooded during the construction of hydroelectric dams around the world.

As the traditional logging industry deals with unsteady prices and the challenges of globalization, the value of a new crop is coming to light: trees hidden under reservoirs, long given up for lost.

The global market for industrial wood products (including wood and paper) is a $400 billion industry, according to From Forests to Floorboards: Trends in Industrial Roundwood Production and Consumption, a 2001 report from the World Resources Institute.

Barges and divers have long gone after both standing trees and abandoned, sunken logs, but it is a slow and dangerous process. Now technology is lending a helping hand, allowing submerged trees to be cut more quickly.

A robotic 3-ton submarine, the yellow Sawfish (in the picture above) is going under to get the job done. An operator works in a control booth on a barge, directing the robot to the base of a standing tree. A hydraulically powered grapple (driven by vegetable oil, not hydraulic fluid) grabs the tree, and the sub screws a large air bladder to the trunk and inflates it. After the Sawfish saws the trunk with its 40-horsepower electric chain saw, the bladder lifts the tree to the surface. Workers then remove the bladder and the tree's limbs.

Capable of operating in up to 1,000 feet of water, Sawfish can cut up to 10 trees an hour. That's somewhat slower than conventional harvesting techniques, but each dead tree harvested by Sawfish can be another live tree saved.

The company that designed Sawfish, believes its submersible could save about 20 million live trees in British Columbia alone.

An estimated 200 billion board-feet of high-quality timber are thought to be standing on reservoir floors behind the world's 45,000 major dams. That's more than six times the amount of timber harvested each year in the United States.

With underwater logging, every acre of drowned trees that is chain sawed in a hydroelectric reservoir should translate into an acre of forest that's left standing. And that, in turn, could translate into significant environmental benefits for the world.