Voyage to the top of the trees

June 8, 2007 | Flying around the planet via Google Earth, it's easy to despair that there is nothing left for humans to discover. Having mapped every inch of the planet with satellites, we can type in London or Darfur or Redwoods National Park and see pigeons circling above Trafalgar Square, a tent city spreading out across the desert, or the green expanse of the forest canopy. This ability to instantly possess images of almost any place on any continent, to zoom in on a certain tree or building (hello, Dick Cheney!), then zoom out as if piloting a plane, can make the world feel like an entirely known quantity, bereft of mystery.

Then comes Richard Preston's thrilling, wondrous book "The Wild Trees." Trees -- the most familiar and beloved of all plants -- turn out to be as unexplored by science as Tibet was by the West before Alexandra David-Néel dressed as a man and sneaked over the Himalayas into the forbidden kingdom. The tree of life may be the archetypal symbol of the human experience, but we don't know as much as we thought about the life of the tree -- especially that of the redwood, the tallest species of tree on the planet. Higher than the W Hotel in downtown San Francisco, redwoods can grow to be 370 feet tall, and until very recently nobody thought, or dared, to climb them.

But a new breed of tree-loving eccentrics -- some of them are scientists, others have an almost mystical attraction to the species -- has discovered a world above the forest floor, an aerial forest 250 feet aboveground teeming with biodiversity that is largely "undescribed" by science. "The forest canopy is the earth's secret ocean," Preston explains, "and it is inhabited by many living things that don't have names, and are vanishing before they have even been seen by human eyes." Possessing amazing regenerative powers, redwoods react to ravages of nature such as fire, drought or lightning by sprouting new trunks, as many as 200, from the old main trunk high in the air. The granddaddy trees can live between 2,000 and 3,000 years, approximating the age of the Parthenon.

The patches of virgin coastal redwood forest that dot the map in Northern California in Mendocino and Humboldt counties were protected from logging operations by conservationists in various stages from the 1900s through the '60s. Comprising 170,000 acres, this remaining redwood country represents only 4 percent of the virgin rain forest that once blanketed the coast from Big Sur to the Oregon border. The light in these forests has an enchanted, golden quality as it filters down through the dense canopy above, which is often licked by fog rolling in from the Pacific Ocean. Coastal redwoods, or Sequoia sempervirens, thrive in the damp, temperate climate just out of reach of the salt air. Preston, who in the course of writing this book became an elite tree climber and one of only several dozen people to have entered the deep redwood canopy, compares the remaining shards of forest to "a few fragments of stained glass from a rose window in a cathedral after the rest of the window has been smashed and swept away."

A science writer for the New Yorker known for his "dark biology" series of books about biological warfare and killer viruses, Richard Preston has written extensively about the fearful power of nature, especially when unleashed by human ignorance, arrogance and greed. "The Wild Trees," which began as a story in the magazine, is also a cautionary tale, about the destruction of the forests, and especially forest canopies, where half of all species on earth are thought to exist. But really it's a love story -- about love of nature and discovery, of tree climbing, and of botanists for each other. It's so beautifully written that I found myself reading it out loud.

Back in the 1980s, Steve Sillett, the man who would become a world-renowned forest canopy botanist, took a trip to redwood country in a beat-up old Honda with his brother, who was visiting from Arizona, and a fellow student from Reed College in Portland, Ore. Just 19 at the time, Sillett "had flaring shoulders, and his eyes were dark brown and watchful, and were set deep in a square face." Sillett had already started climbing Douglas firs in Oregon, but he wanted to see the even bigger redwoods in Northern California. Without a clear plan, the three young men plunged into Prairie Creek Redwood State Park and started bushwhacking through the dense forest until Sillett suddenly tossed off his pack, stared up at a 300-foot redwood and declared, "I'm lusting for this tree."

While Sillett's brother watched in horror below, fearing that Steve had lost his mind, Sillett and his friend Steve Marwood threw themselves into a small tree next to the giant and climbed branch by branch to its top, which is called a "leader." Seventy feet aboveground, the leader swayed under his weight as he stared across the gap between himself and the lower fragile branches of the immense redwood trunk. Struggling to control his fear of heights, he threw his body into space and grabbed the branch like a trapeze, landing safely in the tree. Sillett and Marwood climbed the crown of the immense tree they called "Nameless," entering a dense labyrinth of branches more than 200 feet high holding beds of soil where masses of ferns, lichens and ripe huckleberries grew.

"The top of Nameless had been sheared away in a storm that occurred many centuries earlier, and the tree had reacted by driving a radiance of branches spreading horizontally in all directions away from the broken trunk, like spokes coming from the hub of a wagon wheel. Those branches had sprouted vertical trunks, like spikes on a crown. A forest of small redwoods had sprung out of the top of Nameless -- Nameless Wood." As far as anyone knows, Sillett was the first person ever to visit the upper redwood canopy. It was one of "the last unseen realms on the planet." He has dedicated his life to canopy science, going on to make the first 3-D map of the upper reaches of a virgin redwood grove, where new species, such as earthworms and lichen, are still being found. He also became a master tree climber; never again would he climb a giant without the proper equipment -- it's a miracle he didn't die that day.

The redwood defines "superlative," not only in terms of big, but in terms of complicated. It is "the largest and tallest individual living organism that has appeared in nature since the beginning of life on the planet." The fern gardens in old redwood crowns are second only to Olympic Peninsula rain forests in their density, and scientists estimate the crowns hold so much water they function as airborne aquifers, supporting species such as salamanders and copepod crustaceans, the most abundant animals in oceans. The oldest titans, such as Ilúvatar, in Prairie Creek Redwood State Park, contain some 37,000 cubic feet of wood and are so dense you could "put on a pair of snowshoes and walk around on top and play Frisbee there." Many of the trees, Preston explains, reiterate themselves numerous times in the crown, repeating their own shape in smaller scales of size in the form of a fractal. Ilúvatar has done so six times, creating "Ilúvatars within Ilúvatars, " and is considered one of the most complex living structures ever discovered.

Next page: Look at the 25th floor of a skyscraper: That's where the first solid branches appear