環(huán)球英語 — 282：Life in the Canopy
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Thank you for joining us for today’s Spotlight. I’m Joshua Leo.
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And I’m David Bast. Spotlight uses a special English method of broadcasting. It is easier for people to understand, no matter where in the world they live.
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In the early 1970’s scientists discovered a whole new world.
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This world was not a new planet. It was not a new star or comet.
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In fact, the scientists did not even leave the Earth to find this new world. They just looked up!
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Today’s Spotlight is on tree canopy exploration. Many scientists are exploring the tops of trees. They are finding that a whole new world exists, right above our heads!
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Rainforests grow in many places around the world. One of the world’s most famous rainforests is the Amazon rain-forest in South America. The oldest rain-forest is the Daintree rain-forest in Queensland, Australia.
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But all these rainforests have some common qualities. Rain-forests grow in different layers. The first layer is the forest floor. This is the soil and plants that grow under the trees on the ground. The second layer is the understory layer. This layer exists between the ground and the leaves of the trees. The third layer is the canopy. This is the layer where the leaves start. The canopy extends up through the thick leaves until the final layer, the emergent layer. The emergent layer is the very top of the tallest trees. This layer faces most of the weather extremes - heat, wind, and fierce rain.
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Scientists are most interested in the rain-forest canopy. Before scientists started exploring forest canopies, they thought Earth was home to just a few million different kinds of plants and animals. But they were wrong!
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For many years, scientists did not have an easy way to study rain forest canopies. A scientist had to have special climbing skills to reach the canopy. And most scientists did not have those kinds of skills! The canopy was one of the last unknown areas to study. But today, it is clear that the canopy holds an amazing number of creatures. This biodiversity is very important. One scientist said,
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“Tropical forest canopies have been called the last biological frontier. We know very little about what is going on in forest canopies. But, early studies show that there is great biodiversity, particularly insects and fungi plants.”
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Today, scientists have found ways to reach the canopy. Some of them use rope systems to climb up into the canopy. Some use hot air balloons to fly above the trees. And, other scientists use special machines - cranes. The cranes lift them high into the trees. In Queensland, Australia scientists have recently started using one of these cranes. The crane has been in place for four [4] years. And, in that short time, scientists have identified about fifteen thousand [15,000] new insects!
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However, scientists are finding more than just insects in the forest canopies. They are finding many new kinds of plants and animals. Scientists now estimate that rain-forest canopies hold more than thirty million [30,000,000] different species of plants and animals.
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Nalini Nadkarni is one scientist who works in tree canopies. She describes her first experience up in a tree.
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“I climbed the tree much like an inchworm. Once in the canopy I entered another world, one with its own weather, smells, sounds, and life. Around me were flying birds, bright coloured insects, and sky. From my seat in the tree I could see for miles all around.”
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Nalini has spent many hours in tree canopies all over the world. She studies one of the most interesting plants in the canopy, a plant called an epiphyte. Epiphytes are also called air plants. That is, they do not grow roots in soil to survive. They grow around and on the tree trunks. And they take in water and nutrients from the air. These nutrients are chemicals necessary to life.
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Epiphytes are very important to canopy life. A single tree can be home to several tons of epiphytes. They provide food, water, and shelter to many other canopy animals. Flying bats feed on the sweet liquid from the epiphyte. Water collects in epiphyte leaves when it rains. Tree frogs and insects lay their eggs in this water. Other animals, like snakes, search this water for food.
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And even when epiphytes die, they provide something important. When they fall to the ground, they break down into the soil of the forest floor. But often, they do not fall to the ground. Instead, the epiphyte decomposes in the thick leaves of the tree canopy. It breaks down and becomes very rich soil. This soil is filled with different kinds of insects like worms, beetles, and ants. This soil is different then the soil on the ground. So it grows its own special plant life. Nalini describes the importance of the epiphytes.
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“We think that epiphytes are probably a “keystone species”. That is a kind of plant that performs such an important purpose that if it were to die out, all the other species that depend on it would suffer or move away.”
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Many plants in the rainforest canopy depend on epiphytes. But the truth is, all the plant life in rain forest canopies has an important purpose for us too. First, twenty-five [25] percent of all our medicines come from rain forest plants. And many more medicines may be possible. Scientists hope to discover cures for many serious diseases, including cancer and AIDS.
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Second, the canopy has a very important job in protecting the earth’s atmosphere. Nalini explains.
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“The canopy acts as the lungs of the rain forest.”
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Like human lungs, the trees breathe in and out. But the trees “breathe out” water and oxygen. They “breathe in” large amounts of carbon dioxide. The carbon dioxide helps the trees to grow. Without rain forest canopies, humans would have less oxygen and water. They would have more of the harmful gas carbon dioxide.
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Many people know that rain forests around the world are in great danger. People cut down the forests to use the wood, to raise cows, and to use the land for farming. Others cut down the forests to mine for oil or other materials. They may not know that by cutting trees they are actually killing the majority of plant and animal species on Earth. They may even be cutting down the cure for cancer or AIDS.
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In the Bible it says, “And the Lord God made all kinds of trees grow out of the ground, trees that were pleasing to the eye and good for food.” Trees are a gift. They provide us with many good things. God created the Earth for us to enjoy, not to destroy.
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As rain forests continue to disappear, it will become more and more important to protect them. That is why learning about rain-forests and their resources is so important.
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Not all of us can climb high into rain-forest trees to explore life in the canopy. But, we can learn about them through the experiences of others. And what we learn, we can pass on. Together we can help protect the trees and continue to enjoy them.
