In my community its various
organisms are linked in a complicated web of relationships.
There are usually in balance with
one another. If the natural web is disturbed, the results my be
disastrous. As a rule, the
various populations of organisms tend to adjust to seasonal and other
changes, and the whole community
stays in balance. Most disturbances come from man's
activities.
In an undisturbed forest,
white-tailed deer feed on plants of various kinds. Wolves and
mountain lions prey on the deer.
When deer are numerous, their enemies become numerous too,
because them is so much to feed
upon. The deer and their enemies stay in balance with one
another.
Then man enters the scene. He
looks on aninuls such as wolves and mountain lions as
harmful. He kills as many as
possible. When the animals that feed on deer are killed, the deer
multiply, without check. Soon the
large deer population has eaten nearly all the plants available
for food. Then the deer begin to
starve.
Another example of man's
interference with natural communities is the use of chemical
insecticides. Grass in the
sprayed areas my he eaten by cows. As a result, the milk of some
cows has been found to contain
too much DDT. The insecticides are also collected in the tissues
of birds that eat the sprayed
insects. Some of the affected birds lay eggs that do not hatch. The
number of birds therefore
decreases, cutting down the food supply of other animals.
Whether intended or not, almost
every change that man has made in natural webs of life
has turned out to be a disaster
for the communities involved. Man, of course, is part of the
world's living community.
Everything he does affects all the rest of it, just as my change in the
community or climate around him
affects his own well-being. Thus, by changing natural
communities, man may harm
himself.
1 . What is the text about
.......
A . Forests
B . Disturbed forests
C . Disturbed communuties
D . A complicated web of
relationships
E . The interference of men with
natural communities
Kunci : E
Penyelesaian :
Keseluruhan isi wacaaa
manceritakan tentang campur tangan manusia dalam komunitas
alam (paragraf 3).
(The interference of man with
natural communities).
