The Biological Richness of Rainforests
Rainforest are amazingly rich in species. Whereas a New England forest may have 20 or 30 species of trees at most and a coniferous forest may have only one or two tree species, a 25 hectare plot near Camp 41 in the Amazon has 295 species of trees. A single tree in Peru has more ant species than all of the United Kingdom. And the Amazon River system has 3000 species of fish -- more than the entire North Atlantic.
Life builds on life in these forests. Lianas loop around more than one tree at a time. Epiphytes like bromeliads and philodendrons cling to the tree trunks. Within each bromeliad there is a tiny microcosm of species living in the water trapped by the whorl of leaves: microbes, invertebrates, insect larvae and some frog species use them as a place to lay their eggs.
The richness in species in rain forests is part of a general pattern of ever more species from the poles to the equator. At the tip of South America in Tierra del Fuego there are only two species of ants. At the very edge of the tropics in Sao Paulo Brazil there are 222 species of ants, with the equator still a very long distance away. This pattern is not universal for all groups of organisms. For example, there are very few species of bumblebees in the Amazon and almost no bears in any rainforest.