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Rainforests: Much to Discover
& Much to Understand
Not surprisingly, rainforests are teeming with species unknown to science. New species are being discovered all the time; not just of small organisms like insects but also of birds and monkeys.
Thirty or forty years ago, the number of species known to science was about 1.5 million (all kinds of organisms from microbes to orangutans), and it was thought that perhaps an equal number remained to be discovered. Then Smithsonian biologist Terry Erwin managed to sample insects from a single canopy tree in Peru and found so many previously unknown species that he raised the estimate of the total number of species on earth from three to thirty million. That number has bounced around subsequently between ten and 100 million, while the number of described species has inched forward marginally. At best we know one out of ten species with which we share the planet.
Whatever the total number of species on earth turns out to be, a substantial fraction of these unknown forms of life will be found in rainforests. These forests are filled with complex relationships. In both South America and Africa ants (army ants in South America and Safari Ants in Africa) occur in colonies of half a million or more. They have life cycles during part of which they are in swarming state and advance across the forest floor going through the leaf litter and up and down small tree trunks in search of small prey. Pioneering ecologist Charles Elton called this the most macabre ecological event he had ever witnessed.
In South America there is a set of bird species that make their living by following army ant swarms and snatching some of the fleeing insect and other prey before the ants get them. That, in turn, is a sufficient concentration of birds that a moth species specializes in following those birds and feeding on their droppings.
The pollination of the Brazil nut is similarly complex. Brazil nut trees will grow in plantations, but produce few or no nuts. The reason is the Brazil nut has a complex flower and is principally pollinated by one species of bee which has the heft to get into the Brazil nut flower. That bee needs a series of other trees to depend on during those months the Brazil nut itself is not in flower. As a consequence almost every Brazil nut anyone has ever eaten has been extracted from the Amazon forest, not from plantations. Brazil nuts are a major commodity taken from Brazil’s “Extractive Reserves”, along with natural rubber.
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