Realizing that it's impossible to guard every tree in every place, Mittermeier and CI advocate a focused, two-sided strategy. One priority, based on the ideas of British conservationist Norman Myers, is to protect the world's "hot spots," areas that are disturbed by human activity but still exceptionally rich in animal and plant species found nowhere else. CI has identified 25 hot spots where preservation efforts could have maximum benefit, such as the island of Madagascar and the Atlantic forest region of eastern Brazil. The other priority is to watch over tropical wilderness areas relatively untouched by people, including the upper Amazon region of South America and the Congo basin in Central Africa.

In both hot spots and wilderness regions, CI pushes for the demarcation of key reserves that will forever be off limits to agriculture and industry. But just as important is the nurturing of other territories where healthy forests and human enterprise can coexist. CI has a simple message for developing countries: Your forests are more valuable intact and alive than they are chopped down and dead. Profits could come, for example, from the marketing of exotic foods, chemicals and medicines found only in the rain forest and from the largely untapped potential of ecotourism.

No place is wilder--or more worth saving--than Suriname, a country with only 400,000 people in a territory the size of New England. Mittermeier holds a special affection for this remote wedge-shaped corner of South America. It is where he did his doctoral research, and lately it's the site of his greatest success. Last spring, at CI's urging, the government decided to create the Nature Reserve--about one-tenth of the entire country. CI set up a private trust fund, with contributions from around the world, to help Suriname guard and manage the protected area. Outside the reserve, CI has worked with local Maroon tribes to limit farming to certain slash-and-burn areas and not disturb most of the forest surrounding their villages.

It takes barely 15 minutes for a small prop plane to carry Mittermeier and me from Suriname's capital city of Paramaribo south into pure wilderness. We survey enormous stretches of green, both breathtaking and monotonous. The green is in fact multicolored--brown-green, gray-green, yellow, smoke, even red. There are no roads, no human signs. We land at the base camp at Raleighvallen, where, with two guides from CI, we take a corjal--a long, slender canoe--to a point downriver. There we begin the three-mile trek to a camp near the Voltzberg Dome, a high eruption of granite that looks like an elephant half buried in trees, from whose summit one may gaze out over the wilderness.

I soon discover how awkward I am on this kind of walk: if Mittermeier is Tarzan, me Jane's grandmother. I stumble frequently and cut my hand on a rock, but eventually I turn clumsiness to my advantage by forcing everyone to slow down. I am seeing the jungle for the first time. Here alone are 300 species of trees. They are at once the pillars and the superintendents of the rain forest, the frame of the house and its chief occupants. The spiny understory palm trees make baskets from branches growing out of their trunks, which become compost machines for falling leaves, which in turn sustain the trees. Since the soil is not deep enough for roots to penetrate, the larger trees like the ceiba have buttresses that lie flat on the platform of the forest; some of the narrower trees are supported by stilt-roots at the base that look like whisk brooms. The Parkia tree rises to the sun and spreads a flat umbrella over the others. There is full employment. Trees support lizards and insects, which themselves support birds and monkeys. Army ants bivouac and hang from tree limbs in living nests, with their pupae asleep in the center. Sometimes the trees become food; they can be devoured by strangler figs, which grow from seeds dropped by birds, then rise and surround a tree like a parasitic vine, swallow it whole and take its place.

If a tree falls in the forest and nobody hears it, according to Mittermeier, he would be better off. He tells me that the scariest sound he ever heard in the rain forest was the explosive crack of a dead trunk, followed by a rush of plummeting branches so loud it might have been a storm.

The sound of the moment is the screaming piha, a dull brown-gray bird whose sex appeal lies in its voice--specifically a three-syllable whistle that cuts through the air. As a mate getter it is evidently as attractive as the brilliant orange-and-black plumage of the cock of the rock, the cock of the walk of Suriname's birds. We catch sight of one preening on a high branch. Its head has a flattened crest that looks like a fan from the side, with an eye at bottom center. It makes its nest on the sides of rocks like the Voltzberg, where predators cannot get at it.