Geography Reference
In-Depth Information
belt shifts north and south with the seasons, it never wanders far enough afield to result in a
genuine dry period.
Incredible forests!
Tropical rainforest vegetation is the definitive natural-landscape feature. This plant assemblage is
dominated by broadleaf evergreen species that grow to about 150 feet in height. Their adjoining tree
tops create a “closed canopy” that in turn give rise to vertically arranged ecological zones between
the ground and tree tops, each comprised of different plant species. Add to that the following:
A year-round growing season (which accommodates a wide range of species)
The lack of frost and drought (which also accommodates a wide range of species )
The great age of the rainforest (which has encouraged mutation and genetic drift)
The result is the greatest concentration of living things (especially as regards to plants) to be found
anywhere on Earth. How great, you ask? Well, in a square mile of forest in Vermont, you may find 12
to 15 different species of plants. In tropical rainforests, 300 to 400 different species are not unknown
in comparable-size areas.
Not only is the variety of plants found here great. So, too, is their potential as sources of food and
medicine. The latter is particularly important because a high percentage of medicinal drugs — includ-
ing anti-carcinogens — utilize chemical compounds derived from tropical plants. Thus far, however,
only a relatively small percentage of rainforest plants have been analyzed for their food and medi-
cinal values. Also, because plants take in carbon dioxide and give off oxygen, the tropical forests are
important to maintaining global atmospheric balance.
Endangered forests
Despite their real and potential benefits, tropical rainforests have been disappearing at an alarming
rate. Reasons include:
Rapidly rising populations in rainforest countries, which encourage conversion of forests
to farmlands
Global demand for timber coupled with technological developments that make rainforests
more harvestable than ever before
Government programs that encourage settlement of rainforests either to assert ownership
of remote areas or to relieve population pressure in other parts of the country
