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The Ecology of A Rain Forest


In 1980, the estimated amount of rain forests in the world
was 40,000 square miles. This number decreases each year by
roughly 1,000 square miles due to construction and the
resources being used for profit. It is too bad, because the
rain forest is one of the most beautiful places on earth.
It is the most diverse, containing the most species of
living things, much more than anywhere else, and most have
yet to be identified. All rain forests are located on
earth's "green belt", that is, the area roughly around the
equator that covers all the area from Mexico and the
northern area of South America, to Africa, to India,
streching out to Indonesia, the northern tip of Australia
and all the way to New Guinea. This area is heavily covered
with flora and fauna, and it abounds with life. In a rain
forest, it is very wet and it rains every day or every
other day very heavily. There is a high and steady level of
heat and moisture. There are some general layers to the
rain forest. It starts 135 feet up in the air, with the
lofty crowns of the tallest trees in the jungle. They take
the most light, heat, rain and the most punishment from the
winds. Woodpeckers hunt insects in this layer, and also the
black and white Colobus monkey can be found here, ready to
lauch into the air, using his specially developed tail as a
rudder to guide his flight. Beneath this is the second
layer of trees, whose crowns form a forest canopy. Rain
filters through this canopy, and the top sides of the
crowns hold a large amount of ferns and other small plants
whose roots never touch soil. They live off the water and
nutrients held in the small pockets of the leaves and
branches. Tree frogs and chimpanzees live here, burrowing
holes to live in the vast vegetation. The third layer is
called the "understory". This grows beneath the canopy. The
gorilla makes this his regular hangout, also pythons lie
here waiting for prey. The dim forest floor teems with
life. Termites and ants feed on all the decomposing matter
on the ground, and elephants make their way down a path of
moss. Butterflies move silently by, and the air is still
and very humid. These are the layers that make up the rain
forest's complex ecology. In the rest of the essay I will
describe some of the life forms found in the rain forest,
and ways they affect the environment. In the rain forest,
plants develop poisonous alkaloids to protect against
insects, and insects develop complex digestive chemistry to
overcome these poisons. Some of these plant alkaloids give
native indians great poisons for darts, and to cancer
researchers hope for a new medicine. The rain forest root
systems are so efficient that almost all of the nutrients
in decaying plants are recycled into new ones. Most roots
are found within three inches of the surface in heavy clay
or at the surface in sandy soils. Tiny rootlets grow up and
attach themsleves to leaves. When the leaf decays,
miniscule fungi on the rootlets take over and send
threadlike projections into the leaf which absorbs all of
the leaf's nutrient material. The phosphorous that the
fungi produces is taken by the root, and in turn gives the
fungus sugars from the tree. Also, termites and ants break
down the forest litter. In a small lake in the middle of
the rain forest, a small lizard skims across the water away
from danagerous prey and attacks its own victim by suprise,
yet another marvel of the tropical rain forest. Mutualism
occurs in the jungle with a specialized ant and a
swollen-thorn acacia. The acacia provides budlike leaflet
tips which are called Beltian bodies, which the ants give
to their young for food. The insects hollow out the tree's
thorns when soft and green and raise their young inside.
The acacia doesn't have chemical defenses to repel
dangerous and damaging insects and demands pure sunlight
for proper growth. The ants patrol the tree day and night.
If any insect lands on the tree, they bite it with a
poisonous sting. They also attack plants that grow onto the
tree, such as a vine. In this case, they would attack the
vine at it's base and pull it off the tree. There are also
small leaf-cutting ants in the jungle that cut a portion of
a leaf, bring it to their home, and chew it to a pulp and
inject a body fluid to create a wet mulch. On this mulch
grows the only food of this particular ant -- a fungus that
has only one species. The mysterious part about this is
that any spores that could develop on the mulch and
contaminate it don't develop. Paper wasps in the rain
forest have to bail out their home after a heavy shower.
They lap up a mouthful of water from the colony, and then
spit it out onto the forest floor. They also coat the small
stalk that attaches the nest to the branch of a tree with a
sticky black sectretion that repels some ants. But there
are still some predators, such as jungle katydids which eat
the leaves, and some species of ants that are not repelled
by the black secretion. In one rain forest, there is a kind
of toad that is voiceless. So for the male to attract a
mate, nature gave it a very noticeable characteristic -- a
flourescent orange color, which is unmistakable. The
females are blackish green with scarlet spots on them. In
April and May, mating takes place. Where pools are formed
on the forest floor by water trickling down trees, females
lay around 200 eggs. After the males fertilize them, the
embryos live in their aquatic world for about two weeks,
then after that they hatch and mature. This species was
discovered in 1964 and it helped win government protection
for Monteverde, which is the place where these frogs can be
found. Biologist Jay M. Savage, amazed by the frogs, once
wrote "I must confess. . .my. . .disbelief and suspicion
that someone had dipped the examples in enamel paint."
There are other species of frogs, such as the green leaf
frog, whose green body and glowing red eyes is an
incredible sight. They extrude and fertilize their eggs on
a leaf over water. Young that are ready to leave their
embryo drop into the water below. Also the poison-arrow
frog is an interesting variety. The males battle for
dominance and mates. Two can struggle for hours until one
give up and croaks "uncle". Their color warns predators of
their composition which could prove toxic for snakes and
other such beasties. The Dendrobates Granuliferus frog
doesn't have young that develop in water. Instead, the
tadpoles cling to the mother's wet back. She transports
them this way from place to place, usually depositing them
in a cup of rainwater in a high branch safe from predators.
She immerses herself in the water at first until the young
let go of her body and swim into the water. A rare bird
found only in rain forests, the quetzal, is a beautiful
sight. They have long colorful tails which have long been
worn by royalty of the Colombian Indians, who called the
birds sacred. It is beautiful animals like these that might
start spur nations into preserving more of their rain
forests, in hopes of keeping one of the most complex and
interesting ecologies on earth. 


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