Welcome to the Bosque Gigante. Welcome to the giant forest," says Lou Jost. He is standing in a rain forest located on the Osa Peninsula in Costa Rica. It is an area he knows even better than Tom Bradley knows Los Angeles. After his brief salutation, Jost offers nothing further. He and his guest are standing alone in the rain forest and, quite apparently, conversation has come to an end. Jost, 32, does not seem uncomfortable. Normally, he is a reticent man, content, in fact, to go days at a time without saying a word. He prefers to listen as the forest speaks.
From a thicket 20 feet away a low sound like that from a tuba signals the presence of a curassow, a rare turkeylike bird. Far above, one howler monkey offers a throaty call to another, who replies with something that sounds like a chorus from Jingle Bells. Evsceneserywhere, male hummingbirds are buzzing, in hopes of catching the attention of females. And nearly drowning out everything is a drawn-out note performed by a chorus composed of thousands, perhaps millions, of cicadas.
Despite witnessing the seemingly endless ribbon of leaf-cutter ants at work, the undulations of a deadly fer-de-lance as it moves from one hidey-hole to another and the unpredictable flight of a brilliant azure Morpho butterfly, the visitor senses that the real action is taking place in the treetops, hundreds of feet above the forest floor.
Jost came to the same conclusion several years ago. At the time he was enrolled as a doctoral candidate in physics at the University of Texas in Austin. While on vacation in 1981, he drove 250 miles south of Austin to spend a week in a forest in Mexico called Rancho del Cielo. He was enthralled with what he saw there, and in 1982, he arranged a monthlong study break with friends from the university's zoology department to tour the rain forests of Costa Rica. This time, Jost was so affected by the beauty of the forests and the mystery that lay beneath their thick mantle of vegetation that he decided he should shelve his preoccupation with trying to make sense out of cold fusion and "chaos" or whatever the problem of the moment might be in the realm of theoretical physics, and study the very tangible dynamics of rain forests.
The following year, he made a six-month expedition to Costa Rica. One afternoon, Jost found himself alone in Braulio Carrillo National Park, a rain forest near the Atlantic—the Osa Peninsula is on the Pacific coast—kneeling beside a large, freshly fallen tree. "Its high branches were packed with orchids and bromeliads [air plants]," Jost says. "That was when it really became obvious to me how much richness there was above me. Then and there I vowed never again to return to the tropics without figuring out a way to get up there."
Since then, Jost has become one of a handful of scientifically curious adventurers who have begun to reveal the richness of an environment that has been all but unexplored by man. He has lived alone in the top branches of the trees, with his notebook, tape recorder and camera, learning all he can about his lush surroundings. He has come to recognize the importance of rain forests, whose vast numbers and variety of plants, animals and insects are vital to sustaining life on this planet. And he has come to appreciate the fragility of the environment, a concept that will be emphasized to the public at large with the celebration of the 20th anniversary of Earth Day on April 22.
As they compete for sunlight, trees in the tropical rain forests grow slim trunks to amazing heights—50 to 150 feet—before sprouting branches and foliage. Then, in essence, they form a thick, verdant meadow suspended high above the perpetual darkness at ground level.
Yearning to get up into that fecund meadow, Jost recalled tales that he had heard of a similarly inclined American naturalist named Donald Perry, who was said to use a bow, arrow and fishing line to hang climbing ropes over the branches of tall trees. Following his trip to Braulio Carrillo, Jost returned to Austin and bought a powerful hunting bow. He attached a spinning reel to it so that when an arrow was launched, it carried lightweight (4-8 pounds test) monofilament fishing line along with it on its flight. Once the line was looped over a tree branch, heavier test-rated lines could be progressively attached to the initial line and worked up over the limb. Eventually a climbing rope could be hauled over the limb. It was all very similar to the way sailors deploy the thick hawsers used to moor ships.
As he looks about him, Jost's visitor sees his host's purple climbing rope dangling alongside monkey vines on some of the tallest trees in the Bosque Gigante. The system works perfectly. When Jost wants to go up, he slips a mountain climber's harness around his hips and places his hands on one of the metal "ascenders" attached to the climbing rope he has slung over a tall Cariniana pyriformis (a tree in the Brazil nut family that grows to 200 feet or more). Then he puts a foot in another ascender and "walks" up the rope, sliding his hands and feet quickly upward as he goes. The technique actually is more a test of timing and rhythm than it is of strength, and on this point the howler monkeys have nothing on Jost. "When I climb," says Jost, who gives his weight optimistically as 145 pounds, "there is a thrill because if I fall, I die. There's no one around to save me. But I do this constantly, so the real thrill no longer is the climbing, it's the seeing."
Jost is confident in the ascender sling he uses, but because his ropes are left in place for weeks at a time, he worries that animals will chew and weaken them. Whenever he chooses, Jost can let go of the rope, sit back in the harness and look around him in safety; it is a position he exploits to the extreme. Sometimes he will dangle for 16 hours at a stretch.