National Geographic : 2012 Dec
• It's not quite the largest tree on Earth. It's the second largest. Recent research by scientist Steve Sillett of Humboldt State University and his colleagues has con rmed that the President ranks number two among all big trees that have ever been measured---and Sillett's team has measured quite a few. It doesn't stand so tall as the tallest of coast redwoods or of Eu- calyptus regnans in Australia, but height isn't everything; it's far more massive than any coast redwood or eucalypt. Its dead spire, blasted by lightning, rises to 247 feet. Its four great limbs, each as big as a sizable tree, elbow outward from the trunk around halfway up, billowing into a thick crown like a mushroom cloud at- tening against the sky. Although its trunk isn't quite so bulky as that of the largest giant, the General Sherman, its crown is fuller than the Sherman's. The President holds nearly two billion leaves. Trees grow tall and wide-crowned as a mea- sure of competition with other trees, racing up- ward, reaching outward for sunlight and water. And a tree doesn't stop getting larger---as a ter- restrial mammal does, or a bird, their size con- strained by gravity---once it's sexually mature. A tree too is constrained by gravity, but not in the same way as a condor or a gira e. It doesn't need to locomote, and it forti es its structure by continually adding more wood. Given the constant imperative of seeking resources from the sky and the soil, and with su cient time, On a gentle slope above a trail junction in Sequoia National Park, about 7,000 feet above sea level in the southern Sierra Nevada, looms a very big tree. Its trunk is rusty red, thickened with deep layers of furrowed bark, and 27 feet in diameter at the base. Its footprint would cover your dining room. Trying to glimpse its tippy top, or craning to see the shape of its crown, could give you a sore neck. at is, this tree is so big you can scarcely look at it all. It has a name, the President, bestowed about 90 years ago by admiring humans. It's a giant sequoia, a member of Sequoia- dendron giganteum, one of several surviving species of redwoods. By David Quammen Photographs by Michael Nichols David Quammen's new book, Spillover, is about zoo- notic diseases. Michael Nichols photographed Cali- fornia's giant redwoods for the October 2009 issue.