Plants Animals The Amazon rainforest, also known as
Amazonia, is one of the world's greatest natural resources.
Because its vegetation continuously recycles carbon dioxide
into oxygen, it has been described as the "Lungs of our
Planet". About 20% of earth's oxygen is produced by the
Amazon rainforest. The Amazon rainforest gets its name
from the Amazon River, the life force of the rainforest. The
Amazon River begins in the Peruvian Andes, and winds its way
east over the northern half of South America. It meets the
Atlantic Ocean at Belem, Brazil. The main river is about
4,080 miles long. Its drainage basin covers 2,722,000
million square miles, and lies in the countries of Brazil,
Columbia, Peru, Venezuela, Ecuador, Bolivia, and the three
Guyanas. Sixteen percent of all the world's river water
flows through the Amazon delta. Twenty eight billion gallons
of water flow into the Atlantic every minute, diluting the
salinity of the ocean for more than 100 miles offshore. The
Amazon rainforest watershed is home to the world's highest
level of biodiversity. Amazonia receives about 9 feet of
rain every year. Fifty percent of this returns to the
atmosphere through the foliage of trees. Most of the Amazon
River's water comes from the annual snowmelt high in the
Peruvian Andes. Between June and October, the water level
rises by 30 to 45 feet. Tens of millions of acres of
rainforest are covered by water as the flood advances,
reaching as far inland from the main channel as 12
miles. Some 15 million years ago, the
Amazon River flowed westward into the Pacific Ocean. When
the South American plate moved into another tectonic plate,
the Andes Mountains slowly rose up and blocked the flow of
the river. As the river system backed up, freshwater lakes
were formed, and the environment of the Amazon basin changed
drastically. Then about 10 million years ago the river found
its way eastward towards the Atlantic. The Amazon rainforest is the
drainage basin for the Amazon River and its many
tributaries. The northern half of the South American
continent is shaped like a shallow dish. About 1,100
tributaries, seventeen of which are over 1,000 miles long,
drain into this depression. Whenever rain falls in the river
basin, it all drains into Amazon rainforest and into the
Amazon River. The Amazon is the largest river system in the
world. At some points, the Amazon River is one mile wide,
while at other points it can be thirty-five miles wide. At
Belem, where the river flows into the Atlantic Ocean, it can
be 200 to 300 miles across, depending on the season. Some of
the animals that make their home here are river otters,
freshwater river dolphins, turtles, piranha, manatees,
electric eels, and a remarkable, giant air-breathing fish
called the piraracu. The world's largest tropical
rainforest, Amazonia covers more than half of Brazil. The
canopy of Amazonia is less studied than the ocean floor.
Scientists believe that the canopy may contain half of the
world's species. Over 500 mammals, 175 lizards and over 300
other reptiles species, and one third of the world's birds
live in Amazonia. It is estimated that about 30 million
insect types can be found here. Competition for survival is
fierce. This may explain why over millions of years of
evolution so many highly adapted species have evolved in the
canopy of Amazonia. The most intense competition is between
animals and plants. Both plants and animals have made
adaptations to defend themselves from being eaten, and to
overcome these defensive systems. Plants trap sunlight and
turn it into energy for themselves and the herbivores of the
canopy. Some animals found in the canopy are
the harpy eagle, which preys on monkeys, kinkajous, sloth,
reptiles, and other birds. Sloths spend most of their lives
in the treetops. Their diet of low nutrition leaves forces
them to conserve energy, causing the sloth to spend 80% of
its life resting. A large portion of a howler monkey's diet
consists of leaves, which are hard to digest. Their
metabolism is so low that they need to warm themselves up in
the sunlight after a chilly night. Leaf-cutter ants are
responsible for harvesting a sixth of the area's leaves,
bringing leaf fragments to their underground nests. They
play a critical role in the rainforest's ecosystem by
pruning the vegetation, which stimulates new growth, and
breaking down the leaves to renew the soil. The Amazon rainforest consists of
four layers or communities. Each layer has unique
ecosystems, plants, and animals adapted to that system. The
emergent layer is the tallest layer, where trees can be as
tall as 200 feet, and rise well above the canopy. Here they
are exposed to fluctuation of temperature, wind, and
rainfall. The leaves are small and covered with a thick waxy
surface to hold water. They take advantage of the wind by
developing winged seeds that are blown to other parts of the
forest. Trunks can be up to 16 feet around and braced by
massive buttress roots. Some of the animals find everything
they need to survive in the emergent layer and never leave
it. The main layer of the rainforest is
the canopy. Most canopy trees have smooth, oval leaves that
come to a point, known as a drip tip. This allows water to
flow off the leaf quickly and prevents the growth of fungi,
mosses, and lichens. The canopy's leaves are very dense and
filter out about 80% of the sunlight. Many flowers and
fruits grow in this layer. Epiphytes cover every available
surface and bromeliads provide drinking water for the many
canopy creatures, and breeding pools for tree
frogs. The understory only gets about two
to five percent of the available sunlight. The plants find
unique ways to adapt to this shadowy existence. Their
solar-collecting leaves grow large, and are dark green in
color. They don't often grow more than 12 feet in height.
Because there is very little air movement, they rely on
insects and animals to pollinate their flowers. Some grow
large flowers and fruits low on their trunks to allow
larger, non-climbing animals to eat and disperse their
fruit. The largest concentrations of insects inhabit this
layer. The forest floor is the lowest layer
and almost no plants grow here. Only about 2% of the
sunlight filters through. The floor is littered with
decomposing vegetation and organisms that are broken down
into usable nutrients. Many nutrients are locked into this
biomass. Tree roots stay close to the surface to access
these nutrients. Large animals forage for roots and tubers,
while insects like millipedes, scorpions, and earthworms use
the litter as a source of food. Despite all of its abundant
richness, Amazonia's giant trees grow in the poorest of
soil. The top two inches of the acidic soil contains 99% of
the nutrients. Nine tenths of the forest's energy is stored
in the leaves and tissues of the trees themselves. The
forest floor is a porous mass that prevents minerals and
nutrients from being washed away and lost. As soon as a tree
falls, or a creature dies, decomposers begin to turn it into
a food source and mulch. The vegetation to renew the cycle
quickly absorbs the nutrients that are released. This is the
tightest, most efficient ecosystem in nature. The
destruction of one part of the system can spell the
destruction of the whole system. High temperatures and the amount of
rain are the same throughout the year in Amazonia. The
climate is warm and humid, with average temperatures around
79° F. The difference between day and night time
temperatures is greater than those between
seasons. Today, more than 20% of the Amazon
rainforest has been destroyed and is gone forever. The land
is being cleared for cattle ranches, mining operations,
logging, and subsistence agriculture. Some forests are being
burned to make charcoal to power industrial plants. More
than half of the world's rainforests have been destroyed by
fire and logging in the last 50 years. Over 200,000 acres
are burned every day around the world, or over 150 acres
every minute. Experts also estimate that 130 species of
plants, animals, and insects are lost every day. At the
current rate of destruction, it is estimated that the last
remaining rainforests could be destroyed in less than 40
years. Native peoples of the Amazon
rainforest have used different plants for centuries as cures
and potions for their health and survival. Scientists are
now discovering that many of the plants are sources for new
drugs for AIDS, cancer, diabetes, arthritis, and
Alzheimer's. Quinine, muscle relaxants, steroids, and caner
drugs have already been discovered. Today 121 prescription
drugs sold around the world come from plant-derived sources.
Although 25% of all drugs are derived from rainforest
ingredients, scientists have tested only 1% of tropical
plants. Another concern for Amazonia is the
fate of it indigenous people. An estimated 10 million
Indians were living in Amazonia about five hundred years
ago. Today there are less than 200,000 indigenous peoples
left in Amazonia. More than 90 tribes have been destroyed
since the 1900's. Most of the shamans and medicine men
remaining are 70 years old or more. With them goes a wealth
of knowledge of medicinal species of plants and
organisms. 2003
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http://www.extremescience.com/AmazonRiver.htm.
(6/17/03). "National Zoo/ FONZ",
http://natzoo.si.edu/default.cfm "Greatest Places:Notes:Amazonia",
http://www.greatestplaces.org/notes/amazon.htm "Wealth of the Rainforest - Pharmacy
of the World", http://www.rain-tree.com/ "Rainforest Facts",
http://www.rain-tree.com/facts.htm