Engines of Our Ingenuity
No. 1389:
REGROWING OUR FORESTS

by John H. Lienhard

Click here for audio of Episode 1389.

Today, some good news and some bad. The University of Houston's College of Engineering presents this series about the machines that make our civilization run, and the people whose ingenuity created them.

An article in the November 13th, 1998, Science magazine summarizes current reports on the state of forests worldwide. The world's equatorial forests are certainly in trouble. There's the shrinking Brazilian Rainforest. Mexican and Indonesian forests shrink by one percent per year. But the news is better further north.

When I was a child in Minnesota, forests were hard to find. Trees had been leveled for lumber and farmland in the 19th century. Only old-timers remembered the vanished woods. Years later a grade-school friend wrote that he'd retired, bought land in northern Minnesota, and was growing fir trees. I asked if that meant Christmas-tree farming. No, he said, he just liked to see trees grow.

Now this report: Trees, it seems, are flourishing throughout a northern belt around the world. Over the past fifty years, U.S. timber volume has increased by thirty percent. In Europe and western Russia, the increase was 25 percent during the '70s and '80s.

We've lost ground in the Pacific Northwest, but the supply of wood has almost doubled from Minnesota eastward. We're not logging less wood, but we're far smarter about how to log that wood. We're reforesting with faster growing trees, and we're managing more densely planted forests. We're also wasting far less wood.

In 1946 I moved to Oregon, where slash burners dominated the landscape. Bark and other wood tailings went on to those conical sheet-metal kilns, and the haze of burning wood hovered over the land. What we didn't burn, we left on the forest floor. Now slash becomes fiberboard, veneer and insulation. We use everything.

Another huge gain has been the reduction of kerf. Kerf is the width of the cut. It's the portion of the log converted to sawdust as the blade passes through it, over and over. Cuts were as wide as 5/8 inch in the early days of American lumbering. Now thin-kerf saws turn less than an 1/8 inch into sawdust.

It all adds up. The annual savings are now equivalent to some 120 million cubic meters of hardwood. The north is picking up the carbon dioxide conversion that the shrinking equatorial forests no longer provide.

It's important to separate two issues here. One's the need for a supply of both wood and photosynthesis to convert carbon dioxide. The other is the matter of preserving the biological heritage of the surviving virgin forests. That's an important issue, but it diverts attention from the quiet conversion of trees unto a sustainable crop. At the same time, we now carry the responsibility for tending that crop. In 1865, Francis Parkman wrote,

A boundless vision grows upon us;
an untamed continent;
vast wastes of forest verdure;
mountains silent in primeval sleep ...

Well, strike the words primeval and untamed. Better remove the word boundless, too. And, by all means, take out the word wastes. For trees are now precious sustenance -- to be used and regrown.

I'm John Lienhard, at the University of Houston, where we're interested in the way inventive minds work.

(Theme music)


Moffat, A. S., Temperate Forests Gain Ground. Science, Vol. 282, No. 5392, pg. 1253.

I'm grateful to Joyce Derlacki for counsel on the matter of kerf.



Photo by John Lienhard


The Engines of Our Ingenuity is Copyright © 1988-1998 by John H. Lienhard.