Welcome to Part II of our interview series with John Perlin on forests. Perlin is author of “A Forest Journey: the Story of Wood and Civilization,” an important book that has now come out in its third edition. Our topic? Our forests and our civilization. Perlin details the place of forests and wood in our civilization’s evolution.
In case you haven’t read it, Part I in this series can be reviewed here. I believe this is important read for anybody who champions green and sustainable building.
Perlin, a professor of physics at University of California Santa Barbara, is a solar energy specialist and author of “Let It Shine: The 6,000-Year History of Solar Energy.” He believes that reliance on fossil fuels as an alternative for house and water heating, then later the sun and wind, took place only when people began running out of wood.
Perlin’s research, dating back to the Mesopotamian civilization, reveals wood was the principal fuel and building material for all ancient civilizations. “Its abundance or scarcity shaped, in large part, the culture, demographics, economy, internal and external politics, and science and technology of these civilizations,” writes Perlin. Our interview picks up here.
Meyers: What was the world like before the Age of plants and trees?
Perlin: Scientists describe the period preceding the ascendancy of plants and trees, as the Greenhouse Age due to extremely large amounts of carbon dioxide in the atmosphere and subsequent very high temperatures that prevailed worldwide. The sea so much more abounded in life than its scarcity on land that scientists call this time the age of fish. Teeming with reef builders – algae, sponges and coral – shell inhabiting animals called brachiopods and mollusks, and fish, the sea seemed an underwater wonderland when compared to the rocky and thinly plant-covered landscapes where but the tiniest creatures scurried to and fro.
Meyers: Scientists believe this occurred about 383 million years ago in the late Devonian period. What happened?
Perlin: The accelerated transfer of carbon dioxide from the atmosphere to the land began with the rapid global spread nearly 400 million years ago of the first deep-rooted tree, Archaeopteris. It stood about eight to ninety feet high, had a trunk not too different than a pine, had fern-like leaves and grew throughout the old, primarily in riparian landscapes.
Meyers: How did the tree help our planet leave the “Greenhouse Age?”
Perlin: With a sublime and simple process. The dense leaf canopy photosynthetically absorbed carbon dioxide. As the leaves shed, they would have given back the carbon dioxide to the air, but the tree’s deep and powerful root system had broken down rock through which it dug into soil where a chemical reaction eventually locked up the carbon dioxide in sediment which eventually became rock. Soil creation also accelerated carbon dioxide removal by accelerating the amount of acidic carbon dioxide falling as rain drops sealed as minerals as they hit the ground.
Meyers; Were there other forces at work as well?
Perlin: There existed no fungi at the time capable of breaking down fallen leaves, branches, twigs, trunks, and roots and emit carbon dioxide in the process. As time passed they therefore were buried whole and after millions of years under great pressure deep in the bowels of the earth the intact plant material ended up as rich beds of fossils and fossil fuels. Once again, natural forces denied returning carbon dioxide to the atmosphere which the trees had consumed. Remember, too, during photosynthesis trees and plants emit oxygen, as well as consume carbon dioxide, changing the carbon dioxide/oxygen ratio in favor of the latter.
Meyers: And the net effect of life on earth changed?
Perlin: Yes. With logs and large branches and other organic matter cluttering the bottom of shallow waterways, fish-like creatures that had limbs could better propel themselves through the plant debris than their counterparts who depended on fins for their locomotion. Some of these limbed animals also had lungs that could take in oxygen from the air. As the increasing organic debris finding its way into rivers and shallow seas and robbing the water of its oxygen, creatures able to breathe, as well as walk, could escape sure death by making their ascent to land where a mild climate, sufficient oxygen and ozone protection and plenty of food provided by plants awaited them. So began the chain of events that made the land heaven on earth, permitting all things both big and small to flourish there.
Meyers: Our planet has metamorphosed from this heavily forested condition to being almost treeless in some places. We see some Middle Eastern countries today have no sign of forests at all. Please tell me about some of these countries and what happened.
Perlin: Instead of the Middle East, why not look closer to home? At the time of American Independence, the “most striking feature” of the new nation was, according to one European naturalist, “an almost universal forest.” So vast was the American forest then that a squirrel, it was said, could walk from western Pennsylvania to the Mississippi without ever touching the ground. The size of the trees that made up this forest equally impressed visitors. Oaks in the Ohio region rose to 70 feet before branching out and continued another seventy feet to the top. Walnut trees boasted a girth of six feet in diameter. Where today in middle-America can you find forests and trees of such size? We lost these trees primarily to land clearing for farms and cities, to power the steam demons such as locomotives and paddle boats and to heat houses inhabited by the millions who settled west of the Alleghenies.
Meyers: The deforestation we know today, from the senseless clear-cutting of mountain timber in Oregon to eliminating rainforests in South America has happened many times before in our history. Were there ever lessons learned that could be passed along? Please elaborate.
Perlin: An image on a shard from ancient Mesopotamia illustrates a scene of a woman placing a sapling into the ground, obviously involved in reforesting. Thousands of years later, dating from the 17th century depicts a similar scene in England, which, according to the caption, “shews how vacant forests and woods which have been cut down maybe replanted.” Definitely, examples of reforestation in times past should be followed today. The ancient Greeks established sacred groves, protecting old-growth. As old-growth trees serve as the best carbon banks among their cohorts, it behooves us to emulate this ancient practice.