Sunday, March 8, 2009

The Tree: A Natural History of What Trees Are, How They Live, and Why They Matter


Author: Colin Tudge

In the early 1900’s, fruit and walnut growers ripened their harvest in sheds warmed with kerosene stoves. Eventually, forward-looking orchardists switched to electricity, which was cleaner and more reliable. But electric heating had an insurmountable drawback. It turns out it wasn’t warmth that had been doing the ripening, but the ethylene leaking from the smelly old heaters. Scientists now know that ethylene, a derivative of petroleum and natural gas, is also emitted — as a hormone — by plants. Ethylene causes fruit to ripen, and leaves and fruit to drop. Commercial growers use it to thin crops of plums and peaches (so the remaining fruits grow bigger) and to loosen berries in preparation for mechanical harvesting.

“So it is that plants control their form,” Colin Tudge writes in “The Tree: A Natural History of What Trees Are, How They Live, and Why They Matter.” The subtitle is as straightforward as can be, but the book is oddly more — a descriptive catalog of all the trees in the world in which Tudge expounds on how many there are in each family, where they grow, their physical characteristics, why they are ecologically or economically important and the tasty details of their sex lives.

But this book isn’t useful as a guide: its illustrations are few, and there are no keys. It is written as a tribute to the world’s 60,000 species, but it’s hard to say for whom it’s intended. Maybe someone like me, who has a thing for trees, forgets her botany, marvels at what basic science has revealed and turns a sympathetic ear toward humanistic prescriptions for saving the earth.

Like most biographies of objects, this one presents its subjects as essential players on the global stage. Without trees, Tudge says, we wouldn’t be here. They helped form our atmosphere (without photosynthesis there would be no oxygen), they may have helped shape us (we may partly owe our big brain and dexterous hands to millions of years in the trees), they feed and shelter us, and they provide invaluable ecosystem services, like flood control. But Tudge sees grandeur in how trees exist in the world — “The themes of literature are indeed the themes of nature” — and demonstrates it with fascinating stories about trees’ mating and death, their acts of war and peace, their parent-offspring rivalry, their sibling rivalry and the tension between females and males.

Most people appreciate trees for their beauty and awesome utility, but Tudge wants us to know there’s more to it, that it’s hard out there on a pine. Trees must compete every second for “water, nutrients, light and space; and to fend off cold, heat, drought, flood, toxicity and the host of parasites and predators of all conceivable kinds,” he writes. In perpetual dialog with all that surrounds them, trees “gauge what’s going on as much as they need to, and they conduct their affairs as adroitly as any military strategist.” How? By growing toward light; concocting chemical deterrents to pests from raw materials they take from the air, water and soil; thickening their trunks in response to stress; and attracting their animal collaborators when it’s time to reproduce.

Tudge, the author of “Global Ecology” and other books, writes simply and with unapologetic enthusiasm. He also has a sense of humor. Pandas were once carnivorous, he says, but they now limit themselves to bamboo. “Though if you want to catch a panda, lure it into a (bamboo) cage with roast pork. It’s the same with all vegetarians.”

There are dozens of “wow” and “who knew?” moments throughout, until the book in its final section takes a sudden and uncompromising political turn. Thanks to all of us, the earth’s climate is rapidly warming, and trees can’t evolve fast enough to cope with the changes. What to do? Turn away from current development models, which focus on industrialization and will continue to pump out carbon dioxide, Tudge says, and support grass-roots arbo-centric economies.

Tudge calls for a new type of governance, one that takes account of the “realities of soil, water and climate” and the needs of humanity at large. If this sounds unrealistic (because it’s anti-business) try redefining the word. “Realistic,” he argues, should apply to people’s lives — “whether they have enough to eat, and water and shelter; whether they have control over their own lives, and worthwhile jobs and can live in dignity.” Despite sometimes slipping into vagueness, Tudge is courageous to take this stand and risk alienating readers who’ve stuck with him throughout solely for the love of trees and his enchanting way of writing about them.

Elizabeth Royte, whose most recent book, “Garbage Land: On the Secret Trail of Trash,” has just been published in paperback, is a frequent contributor to the Book Review.