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Transcript
Imagine yourself in a tropical rain forest. The first thing you notice is that it is very warm
–around 80ºF (27ºC)–and very humid. You are surrounded by ancient trees towering so
high that you can’t even see their tops. There are so many plants it almost seems as if the
air itself were green. A loud chattering comes from high above you, and you guess that a
family of monkeys is telling you to go away. You hear a soft
rustling nearby and as you turn, a tiny antelope called a
duiker (rhymes with biker) bounds off between the trees.
Brightly colored beetles scatter and a butterfly flits through
the broad leaves. A snake as thick as your arm and at least
15 feet long rests on a low branch just ahead of you, its
tongue flicking in and out. And in the distance, between
layers of leaves and vines, you can see the outline of a gorilla,
one of the rarest and most fascinating of the forest’s creatures.
Maybe it will rain today; rain falls almost every day in the rain forest. Rain forests
get at least 80 inches (200cm) of rain, and sometimes more than 300 inches (750cm),
every year! Look around you—there are trees everywhere, and if you were a scientist you
would notice that they are all different. There may be more than 200 different kinds of
trees in an area the size of two football fields.
The trees are the building blocks of a rain forest. Right ahead you can see a tree
with huge supporting roots spreading out from the base of its trunk like Dracula’s
cape. Lots of rain forest trees have roots like these, which are called buttress roots. They
support the tree’s huge weight in shallow soil and hold it up when winds whip through
the top of the forest.
But there is more to this rain forest than trees. You can see huge vines connecting
the trees. Look—a monkey uses a vine as a ladder up to the treetops. And branches are
covered with epiphytes—plants that use trees and vines for support. More than 2,000
epiphytes grow on one tree near you. Don’t stand for too long under a tree like that. If the
weight of its plants grows too large, the branches could break and come crashing down!
As you walk through this rain forest, it looks tangled and confusing. But the forest
structure is easier to understand if you think of it as layers, like a cake. The tallest rain
forest trees are the emergents. Up to 200 feet high (60 meters), they are the giants of the
forest – as tall as a 20-story building. From the air, they can occasionally be seen poking
up from the canopy. The canopy, made up of trees about 120 feet (36 meters) high, is the
roof of the forest. Here, where the sun hits, the trees spread out
with huge branches in every direction, filling every space
and blocking most of the light from the lower levels. Below
these huge trees, in the understory closer to you, shorter trees grow slowly. They
are waiting for the sunlight to reach them.
Where you stand, you are far below the sunlight of the canopy. You walk
along the forest floor where it is always dusky. The forest floor is alive with the
nests of termites and ants and everywhere you see their long, winding trails. It is
here where you will find leopards, okapis, gorillas, duikers, shrews, goliath frogs,
chameleons, and the spectacular Congo peafowl. Insects are everywhere. In
addition to the dozens of species of ants you might find here, termites build
spectacularly large skyscrapers on the forest floor. One termite mound, shaped
like a strange, multi-layered house, grows from the ground near your feet. You almost
trip over bumpy roots criss-crossing the ground, and you step
softly on fallen seeds and leaves.
The African rain forest is home to millions of species of
plants and animals. In fact, rain forests hold more than 50%
of the world’s species. Most of them haven’t even been identified
yet. Each layer of the forest provides homes, pathways, food and
shelter for its own set of animals. In the rain forest canopy,
crowned eagles look for guenon monkeys to eat. Hornbills
and African gray parrots feed on fruit and seeds, while
swallowtail butterflies flit from flower to flower. Hornbills call
loudly if they see or hear a leopard nearby, and many animals dive below for safety. The
leopard will eat almost any animal it can catch. In the understory, animals move up and
down between forest layers. Chimpanzees climb around searching for food. Golden
pottos move slowly from branch to branch, active mainly at night.
But as you marvel at the wonders around you, in the distance you can hear the loud
sound of a chainsaw, and you know that can’t be good for the forest. Somewhere nearby,
people are cutting down trees for lumber and fuel to build fires and cook food. They are
building roads deep into the forest. If you listen long enough, you may also hear gunshots.
Illegal hunters kill forest animals every day and bring them to markets in the cities to sell
as food. All is not well in the rain forest.
About three hundred years ago, the area where you live was probably completely covered
by forests. Even now in most of the New York City area, you may be able to walk ten
minutes from your home and find a patch of temperate forest. What does temperate
mean? It means that the temperatures in this forest change from season to season. It may
get below freezing (32ºF, 0ºC) in winter and warmer than 100ºF (37°C) in summer. (The
average temperature in the New York region is about 55°F, or 18°C.) These different
temperatures mean that the forest itself also changes with the seasons.
Imagine you are walking in the forest during summer. You see sunlight fall through the
leaves, creating patterns on the ground. It is warm, with a slight breeze that gently rustles
the many leaves on the trees. The leaves are in different shades of green. Mushrooms grow
in their cool, dark shadows.
As you walk in the forest, you will notice that some trees are quite
tall, 80-100 feet, with their leaves way above your head.
These trees make up the canopy layer of the forest.
But the forest also has bushes and young trees,
smaller plants and flowers growing in the understory,
under the tall trees. And look down at your feet—
you’ll see layers of fallen leaves. There are thousands of
creatures that live on the forest floor: worms, spiders, ants,
beetles and salamanders. Some animals use all layers of the forest. Gray
squirrels collect acorns on the forest floor and then scamper up trees to their
nests. Chipmunks dart between fallen logs. Rabbits hop quickly between shrubs. A
skunk rolls over in its daytime sleeping nest. A porcupine runs along the ground looking
for food, but also nests up in a tree. Raccoons may be sleeping during the day, but they
are everywhere in the temperate forest, and they’ll eat anything!
You may not see wolves in the forest near your home, but at one time they roamed
eastern North America and were active parts of the temperate forest ecosystem. If you
are very quiet and look closely, you will see a family of deer not so far away. These quiet
creatures eat leaves, bark, and flowers. In many areas there are now too many deer
eating too much vegetation. Do you know why?
Wolves used to eat them, and there are no longer any
wolves here to keep the deer population from getting too large.
As the summer ends, it begins to get cooler. There is a chill
in the air. Squirrels gather nuts for the cold winter ahead. Some
birds, like warblers, migrate to the south where they can find warmer
temperatures and more food. Many temperate forest trees have
leaves that change colors and drop off in the fall. These are called deciduous trees, and
you probably have heard the names of many, such as oaks, maples, and birches. Their
trunks grow tall and straight. Their roots are deep in the soil. If you looked around the
autumn forest you would see that the leaves are brilliant red, orange, yellow and brown.
And many are on the ground, crunching under your feet. Did you ever wonder why
deciduous trees lose their leaves in fall? It is to conserve water and nutrients and to reduce
the possibility that the tree will be blown down by strong winter storms.
All of a sudden, winter arrives. The ground is covered with soft white snow. The
forest is full of bare trees, reaching their branches like arms up to the sky. But even in winter,
there are some trees here that are always green. They are called evergreens, or coniferous
trees, and they have needles instead of leaves. You have probably seen many of them before,
like pine or spruce trees. They have thick bark and downward sloping branches to help
snow slide off so they won’t break from its weight. Many animals, such as squirrels, red
foxes, raccoons, and birds look for shelter and food here through the long winter. Black
bears still ramble among trees in some forests, but not too near where people live.
And then, it starts to get warm again and winter turns to spring. In the spring, it
begins to rain, bringing flowers and buds and little green leaves back to the forest. It
rains around 40 inches per year, on average. If you listen carefully, you will hear the
songs of many different birds. High above your head, birds are guarding their nests.
Look up—you may see cardinals, blue jays, sparrows, and robins. Do you hear the rapid
ba-ba-ba of a woodpecker looking for insects underneath tree bark? At night, you can
hear the soft who-who of an owl as it scans the forest for a mouse to eat
for dinner. You may see or hear warblers, small birds returning from
their winter homes. Insects once again swoop from flower to flower.
Now you return from your walk through a year in the temperate
forest. Did you know there was once much more forest in the east than
there is now? Can you imagine why? The human population has grown
and grown in the past 500 years in this country. And what do people
need? They need to build houses and roads, burn wood for fuel, and
plant fields of crops for food. And these are still reasons why temperate
forests are cut down—for building, agriculture, and making paper. Eastern
forests are also threatened by tree diseases and acid rain, which kill trees. What will
become of them and the animals that live here?