By. Heather Farmer, and Tylor Johnson
Rainforests now cover less than
6% of Earth's land surface. Scientists estimate that more than half of the
world's plant and animal species live in tropical rain forests. But since there
is so many species of plants and animals, I will only be able to tell you about
a few from the three major rainforests. The American, The African, and The Asain.
Tropical rainforests produce 40% of Earth's oxygen.
A tropical rain forest has more kinds of trees than any other area in the world. Scientists have counted about 100 to 300 species in one 2 1/2-acre area in South America. 70% of the plants in the rainforest are trees.
About one-fourth of all the medicines we use come from rainforest plants. Curare comes from a tropical vine, and is used as an anesthetic and to relax muscles during surgery. Quinine, from the cinchona tree, is used to treat malaria. A person with lymphocytic leukemia has a 99% chance that the disease will go into remission because of the rosy periwinkle. More than 1,400 varieties of tropical plants are thought to be potential cures for cancer.
All tropical rain forests resemble one another in some ways. Many of the trees have straight trunks that don't branch out for 100 feet or more. There is no sense in growing branches below the canopy where there is little light. The majority of the trees have smooth, thin bark because there is no need to protect the them from water loss and freezing temperatures. It also makes it difficult for epiphytes and plant parasites to get a hold on the trunks. The bark of different species is so similar that it is difficult to identify a tree by its bark. Many trees can only be identified by their flowers.Despite these differences, each of the three largest rainforests: The American, The African, and The Asian Rainforest all have a different group of animal and plant species. Each rain forest has many species of monkeys, all of which differ from the species of the other two rain forests. Plus different areas of the same rain forest may have different species. Many kinds of trees that grow in the mountains of the Amazon rain forest do not grow in the lowlands of that same forest.