When Alexander the Great conquered the Punjab in India in the fourth century B.C., western man first became conscious of rainforests. For hundreds of years Europe relied on the information brought home by Alexander’s soldiers; this information was codified in the same century by Theophrastus in his Enquiry into plants. Not much was added to this unreliable source until Europeans began to explore beyond their continent in the sixteenth and seventeenth centuries. During the course of these explorations many plants and animals were sent back to Europe, where people struggled to put them into taxonomic order. The inherent bias of these samples led to many misconceptions. Linnaeus, the great Swedish taxonomist who established the modern taxonomic system, for example, believed that tropical regions contained relatively few species and were relatively uniform. Only in the late 18th and in the 19th century, with the voyages of such men as Alexander von Humboldt, Charles Darwin, and Alfred Russel Wallace, were rainforests recognized as the amazingly complex biomes they are in fact. Since then, scientists have endeavored to collect, categorize, and describe the organisms, ecology, and soils of rainforests, and there have been even more assiduous efforts by commercial interests to exploit rainforests and their products – mainly timber, but also wood for fuel (charcoal), rubber, medicinal plants, tree resins, fruits, fibers, and food products.
Approximately one-third of the surface of the earth (3.54 billion hectares) is presently covered with forest. Of this area, about 150 million hectares are tree plantations, and 500 million additional hectares are actively managed by humans (Noble and Dirzo, 1997). Still more forest has felt the impact of human activities such as collecting, hunting, and setting fires.