Tropical rainforests are the most diverse ecosystems on earth. A four-square mile patch of rainforest contains as many as 1500 species of flowering plants, 750 species of trees, 125 species of mammals, 400 species of birds, 100 species of reptiles, 60 species of amphibians, and 150 species of butterflies. More than 50% of the world's plant and animal species inhabit the 7% of the world that is covered in rainforest.

Why is this so??

Researchers believe that there is such a great diversity of animals because rainforest ecosystems have been developing for hundreds of millions of years. Some forests in Southeast Asia have been around for more than 100 million years, when the dinosaurs roamed the Earth. During the Ice Ages, the last of which occurred about 10,000 years ago, the frozen areas of the North and South Poles spread over much of the earth, causing huge numbers of extinctions. But the catastrophe did not reach many of the tropical rainforests. Thus, these plants and animals could continue to evolve, developing into the most diverse and complex ecosystems on earth.

The high temperatures, rainfall and humidity which provide excellent conditions for life also help contribute to the great number of species. With temperatures at least 24 to 30 degrees celsius all year round, animals don't have to worry about freezing during cold winters or finding shade in the hot summers. Water is rarely a problem for them as precipitation is high throughtout the whole year.

While there are many species of plants in a square-mile of tropical rainforest, there may only be one or two of each. In addition as most of the species are found nowhere else on Earth, by removing one plant or animal, the fragile ecosystem would be threatened, and the species may be forced into extinction.

Other species consist of only a few dozen individuals. Living in limited areas, most of these species are , or found nowhere else on earth. The maues marmoset, a species of monkey, wasn't discovered until recently. Its entire tiny population lives within a few square miles in the Amazon rainforest. It is so small, it could sit in a person's hand!

While there are many species of plants in a square-mile of tropical rainforest, there may only be one or two of each. Removing one plant can severely damage the fragile ecosystem. Animals are dependent on plants for food and habitat. For example, some insects can only live on one type of plant. Destroying the plant can cause the insect to become extinct

Today, through the direct and indirect actions of man such as pollution, species of plants and animals are disappearing from the rainforests even before they can be cataloged and studied. The average rate of extinction in the rainforest is 140 per day and if this goes on, the animal and plant species in the rainforest would be wiped out even before we know it. That would be almost half of the total number of plant and animal species on Earth.