And so the tropics are garlanded with trees, plants, animals and insects, uniquely adapted to these conditions. Exploring rainforests had a profound impact on the thinking of some of the greatest of 19th century biologists and naturalists Alexander von Humboldt, Alfred Russell Wallace and Charles Darwin. Darwin s and Wallace s experiences in rainforests shaped their theories of evolution through natural selection, which in turn inspired 20th century biology, leading to recent advances in molecular biology and genetic engineering. Characteristics Buttresses Soils of the typical lowland rainforest are often shallow. In much of Amazonia, there s only a few inches of soil above reddish clay.
Many roots stretch out over the surface, rather than burrowing underground.
Some biologists say this shape also allows the tree to gather nutrients from a greater surface area of soil since lots of small rootlets extend down from the bottom of the buttresses. In other places, so-called prop or stilt roots emerge like slanting rods from the main trunk 1 to 2 meters above the ground to help support the trunk. This particular kind of root is often found in flooded or mangrove forests, where it also protects the tree against waves and currents. Drip tips Rainforest leaves also have distinctive features. Many have drip tips a pointed shape which helps drain excess water from the leaf and reduces vulnerability to mold and predation.