“The trees of these Indies are a thing that cannot be explained, for their multitude,” exclaimed Spanish chronicler Gonzalo Fernández de Oviedo in 1526. Five centuries later his appraisal is not far off the mark. “The rain forest,” writes author Cynthia Russ Ramsay, is “the most diverse, the most complex, and the least understood ecosystem on earth.”

Tropical biologist Seymour Sohmer states: “We should never lose sight of the fact that we know little or nothing about the way most humid tropical forests are structured and how they function, not to mention the component species.” The sheer numbers of species and the complexity of their interrelationships make the researchers’ task a daunting one.

A temperate forest may contain only a handful of tree species per acre [per hectare]. An acre [a half hectare] of rain forest, on the other hand, may support over 80 different species, even though the total number of trees per acre [hectare] averages only about 300 [700]. Since the classifying of such diversity is an exhausting and painstaking task, few rain-forest plots larger than a few acres [one hectare] have ever been analyzed. Those that have, however, yield surprising results.

The vast assortment of trees provides innumerable niches for a huge number of forest residents—far more than anyone had imagined. The U.S. National Academy of Sciences says that a typical four-square-mile [10 sq km] area of pristine rain forest may harbor as many as 125 different species of mammals, 100 species of reptiles, 400 species of birds, and 150 species of butterflies. By way of comparison, we note that the whole of North America has or receives visits from fewer than 1,000 bird species.

Although some of the myriad plant and animal species may be found over a wide area of rain forest, others are restricted to just one mountain range. That is what makes them so vulnerable. By the time loggers finished clear-cutting a mountain ridge in Ecuador a few years ago, 90 of the endemic plant species had become extinct.

In the face of such tragedies, the United States Interagency Task Force on Tropical Forests warns: “The community of nations must quickly launch an accelerated and coordinated attack on the problem if these greatly undervalued and probably irreplaceable resources are to be protected from virtual destruction by the early part of the next century.”

Man cannot afford to turn his back on the origins of his food supply. Both crops and livestock can become weakened by too much inbreeding. The rain forest, with its vast collection of species, can supply the genetic variety needed to fortify these plants or animals. For example, Mexican botanist Rafael Guzmán discovered a new species of grass related to modern corn. His find excited farmers because this grass (Zea diploperennis) is resistant to five of the seven major diseases that ravage crops of corn. Scientists hope to use the new species to develop a disease-resistant variety of corn.

In 1987 the Mexican government protected the mountain range where this wild corn was found. But with so much forest being destroyed, invaluable species like this one are doubtless being lost, even before they are discovered. In the forests of Southeast Asia, there are several species of wild cattle that could strengthen the breeds of domestic herds. But all these species hover on the brink of extinction because of the destruction of their habitat.