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Unique - special conditions produce Rainforests
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Tropical rainforests are defined primarily by two factors:
location (in the tropics) and amount of rainfall they receive.
Rainforests receive from 4 to 8 meters of rain a year;
1 meter of rain a year falls on the state of New York.
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Rainforests cover 2% of the Earth's surface, or 6% of its land mass.
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Rainforests are located around the equator, and the temperatures stay
near 75-80 degrees F all year-round.
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A tropical rainforest consists of four vertical layers:
the emergent trees, canopy, the understory, and the forest floor.
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Diverse - many animals and plants live in the Rainforest
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Rainforests are home to about half of the 5 to 10 million
plant and animal species on the globe. Rainforests also support
90,000 of the 250,000 identified plant species.
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Scientists estimate
that there are at least 30,000 as yet undiscovered plants, most of
which are rainforest species.
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A typical four square mile patch of rainforest contains as
many as 1500 species of flowering plants, 750 species of trees, 125
mammal species, 400 species of birds, 100 of reptiles, 60 of
amphibians, and 150 different species of butterflies.
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The tropics are the earth's richest natural reserves. One
fifth of all the birds and plants on Earth evolved in the Amazon
Basin.
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Fragile - the Rainforests are being damaged
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Four-fifths of the nutrients in the rainforests are in the
vegetation. The soils are nutrient-poor and become
eroded and unproductive within a few years after being
cleared.
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Rainforests are being destroyed at a staggering
rate. According to the National Academy of Science, at least 50
million acres a year are lost, an area the size of England, Wales
and Scotland combined.
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Value of land based on usage:
$ Value/
Hectare |
Use of Land |
| 6820 |
intact forest sustainably harvested for
fruits, latex, and timber |
| 1000 |
clear-cut for commercial timber
(not sustainably harvested) |
| 148 |
used as cattle pasture |
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Deforestation to date for some countries:
| Country |
Original |
% left |
% loss/year |
| Brazil |
90,000 |
50 |
2.1 |
| Columbia |
700,000 |
26 |
2.3 |
| Cen. America |
500,000 |
11 |
3.7 |
| Equador |
132,000 |
33 |
4 |
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