Tropical Rain Forests: 
A Global Responsibility 
If the world’s rain forests disappear, 
people everywhere will suffer 
by Peter H. Raven 
Everyone who reads the popular 
press nowadays is aware of the ex- 
traordinary biological richness of the 
world’s tropical rain forests and of 
the present fast pace at which they 
are being cut down. Less generally 
recognized is how little we know about 
the many species of tropical plants 
and animals and how the current de- 
struction of the rain forests makes the 
need to increase our knowledge a 
pressing one. Of the estimated 3 mil- 
lion species of plants and animals in 
the tropics, only about 500,000 have 
been recognized and cataloged. In 
comparison, the temperate regions of 
the world contain some 1.5 million 
species, of which more than a million 
have been cataloged. A large majority 
of virtually every known group of or- 
ganisms occurs in the tropics, making 
tropical forests the richest and most 
diverse association of plants and ani- 
mals anywhere on the earth. About 
as many kinds of plants exist in the 
tiny country of Panama, for example, 
as in the entire continent of Europe, 
and nearly as many kinds of fishes — 
some 5,000 — live in the drainage basin 
of the Amazon River as in the whole 
Atlantic Ocean. The diverse kinds of 
plants and animals in the tropics rep- 
resent a potentially inexhaustible 
source of raw materials, only a minute 
fraction of which has been utilized 
or even tested up to this point. 
The organisms that make up the 
ecological communities of the tropics 
are linked together in extremely com- 
plex ways. Fundamental processes 
such as energy flow and mineral cy- 
cling, which are complex and poorly 
understood even in temperate regions, 
are virtually unknown for the tropics. 
We do know that the rich and diverse 
communities of plants and animals 
that occupy tropical soils are relatively 
stable when undisturbed. They have 
remained stable for millions of years 
and are as appropriate to the climate 
and soils of their areas as the forests, 
swamps, and prairies in the United 
States are to theirs. When farmers 
plow up a prairie in the Midwest to 
plant crops, they are modifying a nat- 
ural ecological system in order to cre- 
ate another productive, sustainable 
system. When agriculturists cut down 
a forest in the humid lowland tropics, 
they are often trying to accomplish 
the same thing. The many differences 
Director of the Missouri Botanical 
Garden in Saint Louis, Peter H. Raven 
served as chairman of the National 
Research Council’s Committee on Re- 
search Priorities in Tropical Biology. 
Composed of scientists from many 
countries, the committee was con- 
cerned with the rapid destruction of 
the world’s rain forests and the need 
to acquire basic scientific knowledge 
about tropical organisms and ecosys- 
tems. Last year, Raven presented 
some of the committee’s findings be- 
fore the Subcommittee on Interna- 
tional Organizations of the House 
Committee on Foreign Affairs. This 
article is adapted from his remarks. 
between the ecological processes in- 
volved in the two instances, however, 
have potentially tragic consequences 
for a large and rapidly growing portion 
of the human race. Once the sorts 
of forests that occupy most tropical 
areas are cut down, a reasonable ag- 
ricultural yield is usually possible for 
only a few years. The cutover area, 
depleted of its fertility, often becomes 
a wasteland, with restoration to its 
original state or to use for any pro- 
ductive purpose virtually impossible. 
Our ignorance about ecological pro- 
cesses in the tropics is compounded 
by our general lack of knowledge 
about tropical organisms. Although 
the vast majority are insects, mites, 
nematodes, fungi, and other relatively 
small organisms, we also have a great 
deal to learn about many species that 
are larger and belong to groups that 
are more familiar. To give just a few 
examples, some ten to fifteen thousand 
kinds of plants in Latin America, in- 
cluding many trees, have not yet been 
scientifically described and listed. 
These plants, which constitute perhaps 
an eighth of the total plants in Latin 
America, are generally viewed as a 
valuable resource, but as long as they 
remain unknown, they cannot be uti- 
lized rationally for human benefit. 
Similarly, many people are counting 
on manipulating the populations of 
fishes in the Amazon Basin and its 
tributaries as a way of increasing food 
production in the future. Competent 
students estimate, however, that ap- 
proximately 40 percent of these fishes 
have not yet been recognized and 
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