Tropical rainforests are found in the area between the tropics of Cancer and Capricorn: in Southeast Asia, the Zaire Basin in Africa and the Amazon Basin in South America.
Tropical rainforests occupy 2,500 million acres or seven percent of the earth's land surface.
Southeast Asian rainforests are the oldest: 70-100 million years old.
There are several types of tropical rainforest - lowland rainforest, subtropical, tropical, montane and submontane - covered in the general term of rainforest.
The largest surviving rainforest is the Amazon rainforest. It contains 25 percent of the world's remaining primary rainforest.
A mature tree that emerges above the main body of the rainforest canopy, an 'emergent,' can be 400-600 years old.
The tallest trees in the rainforest are over 160 feet high.
The average temperature in the Amazon rainforest is 80 degrees Fahrenheit.
The average rainfall in the Amazon rainforest is 120-240 inches annually.
An estimated 73.8 billion tons of carbon are stored in the trees of the Amazon region.
THE AMAZON RIVER AND AMAZON BASIN:
The Amazon River is the second longest in the world, measuring nearly 4,000 miles. Although the Nile is slightly longer (4,100 miles), the volume of the Amazon is 60 times that of the Nile. It discharges 170 billion gallons of water an hour into the Atlantic Ocean, totaling one fifth of the worlds river water reaching the oceans.
The Amazon Basin covers 2.7 million square miles, which is equivalent to almost 90 percent of the area of the contiguous United States.
The majority of the Amazon Basin is in Brazil, but it also crosses eight neighboring countries - Bolivia, Colombia, Ecuador, French Guiana and Guyana, Peru, Surinam and Venezuela.
SPECIES FOUND IN RAINFORESTS:
Latin American tropical forests support 1 million species of plants and animals.
It is estimated that there may be up to 30 million species on Earth in total, but many have not yet been identified. If this is true, then rainforests, covering only seven percent of the earth's surface may be home to between 70 and 90 percent of all Earth's species.
A typical four square-mile patch of rainforest may contain 750 species of trees, 125 kinds of mammals, 400 types of birds, 100 different reptiles and 60 amphibians.
PLANTS:
There are some areas of forest which are particularly rich in species. These areas amount to 120,357 square miles of forest and contain 37,000 endemic plant species (15 percent of all plant species on earth). They also contain 750,000 endemic animal species.
There are around 90,000 plant species in tropical rainforests. Amazonia has 30,000 plant species and is the richest zone.
ANIMALS:
Three tenths of all the species of birds in the world - 2,600 species - can only live in tropical forests. If these forests were destroyed, these birds would become extinct.
One in five of all bird species in the world are found in Amazonia.
There are 2,000 known species of fish in Amazonia - 10 times as many as in the whole of Europe, or eight times as many as in the Mississippi River system.
INSECTS:
700 species of butterfly were collected within one hour's walk from the home of the English naturalist Henry Walter Bates in Brazil's Eastern Amazonia.
Up to 363 pounds of insects and bacteria may exist in a 2.5 acres of rainforest soil.
The tropical forest canopies of Amazonia are only just being studied. It is estimated that tropical forests may contain 30 million insect species, a very large percentage of all earth's species.
FUNCTIONS OF RAINFORESTS:
They affect global climate patterns by producing large amounts of moisture which forms into clouds, and then flows to other parts of the earth where it falls as rain, vital for crop growth.
They produce one third of the world's oxygen.
They absorb harmful excess carbon dioxide from the air.
They soak up rainwater and release it slowly into rivers, maintaining a steady flow of water.
They act as gene pools for refining existing crops.
They provide many raw materials for industrial products and medications.
DISAPPEARANCE OF RAINFORESTS:
Only half of the original six million square miles of the world's tropical rainforest still exists. By the year 2000, it is estimated that one third of remaining forests will be destroyed and in the first 30 years of the next century, another third of today's rainforests will disappear.
Brazil has more than 25 percent of the world's surviving rainforests. But these are now being threatened by mining, ranching, and poor settlers.
Only 20 percent of deforestation in tropical rainforests is due to commercial logging.
Each year, forests equal to the size of Austria, Denmark and the Netherlands combined are cut or burned worldwide, totaling 42 million acres.
1979 deforestation: 29,025 square miles
1989 deforestation: 54,954 square miles
1991 deforestation: 45,279 square miles
In addition to the area of forest totally destroyed each year, as much again is degraded.
RESULTS OF DEFORESTATION:
Clearance of forest takes away the protective cover of trees from the soil and allows the rain to wash the topsoil away, leaving a barren wasteland.
When forests are burned, large amounts of carbon dioxide (previously stored in the trees), are released into the atmosphere. Excess carbon dioxide in the atmosphere traps heat, contributing to the greenhouse effect and global warming. Scientists believe that if present rates of global warming are not significantly reversed, the temperature may rise by five degrees Fahrenheit around the world, leading to the melting of ice caps. The sea will then rise by more than 16 feet and low-lying areas - i.e. Bangladesh, New York - will be severely flooded.
