forests shelter probably more then half of the earths
plant and animal species. With tropical forests being cut at a rate
of 55,000 square miles a year, however, many species perish before
they can be identified or studied.
About 9000 years ago, lakes and crocodiles could be found in the
Sahara, but for the past thousand years the continent has been dry.
Much of Africa is easily damaged by overgrazing and destructive
agriculture. Scientists fear that deserticification
will bring drought to the Sahel south of the Sahara.
Downpours have washed essential nutrients from the ground in rain
forest areas. Even the practice of slashing
and burning does not allow the soil to sustain abundant crops.
Africans once allowed the soil to rejuvenate
itself and used less-fertile land for herding,
increases have forced farmers to misuse the soil by planting too
often on the same land. Animals overgraze. The African forest is
rapidly turning to grassland
which becomes desert