One of former President Ronald Reagan's more notorious remarks concerned the grand California redwoods. There was "nothing beautiful about them," he said, "just that they are a little higher than the rest." 

An inspiring corrective to Reagan's indifference is Richard Preston's The Wild Trees. The author of The Hot Zone follows professional and bare-knuckled gonzo forest ecologists to the "rain-forest valleys of the North Coast," where the last smatterings of redwoods reside. What they find at the tops of these trees is a previously undiscovered ecosystem of riches. 

On the scientific side is Stephen Sillett, now the Kenneth L. Fisher Chair in Redwood Forest Ecology at Humboldt State University in Arcata, who employs a rope-climbing method developed by scientists in the 1970s. At the top of the swaying and often decaying redwood crowns, Sillett discovers "one of the last unseen realms of nature on the planet": Fifty-five different species of mites, massive fern gardens, the second-largest collection of "epiphytes - plants that grow on plants - in any forest on earth," and a species of salamander previously thought to live only on terra firma. 

While Sillett was tree-walking, the relentless Michael Taylor, an unconventional naturalist with a fear of heights, was bushwhacking on the ground through the thick understory of poison oak, looking for the elusive "Mount Everest of All Living things": "He had a strong feeling that the most inaccessible parts of the redwood forest along the North Coast had never been thoroughly explored. The world's tallest living thing was out there, somewhere, perhaps hidden in a lost valley." 

Taylor and fellow naturalist Chris Atkins would eventually find that tallest tree, which they named "Hyperion." Sillett climbed it and measured its height at 379.1 feet and growing. 

Sillett and company may have just scratched the surface of the critical importance of deciphering the secrets of the redwood canopy ecosystem. They estimate the height limit of the redwood - the world's tallest plant - to be close to 420 feet. As Preston notes, with most of this planet's tallest forests now sadly gone, the remaining ancient giants - the redwood, Douglas fir and Australia's soaring mountain ash - may "reveal clues about how forests are responding to increasing levels of carbon dioxide brought on by human activity, and the resulting global warming." 

The Wild Trees: A Story of Passion and Daring

Richard Preston

320 pages, hardcover: $25.95

Random House, 2007.