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Streda, 5. októbra 2022
Rainforests
Dátum pridania: 07.12.2002 Oznámkuj: 12345
Autor referátu: mylan
 
Jazyk: Angličtina Počet slov: 689
Referát vhodný pre: Stredná odborná škola Počet A4: 2.5
Priemerná známka: 3.00 Rýchle čítanie: 4m 10s
Pomalé čítanie: 6m 15s
 
1)Introduction:

The rainforests are 3,4 million square miles of tropical forest that encircle the equator. Before 1900, rainforests covered 14% of the world’s surface. Today they cover 2%. The reason is simple. They have been cut down to provide: land, paper, wood, medicines, minerals, fuel,… But it’s not only trees disappearing. Although rainforests cover less than 2% of Earth’s surface, they are home to more than half of all its living things. Land half the size of San Francisco contains 545 kinds of birds, 100 species of dragonflies, and 729 kinds of butterflies. Two hundred ond five kinds of mammals, 845 types of birds, and 10,000 different varieties of plants inhabit the Costra Rican rainforests. This animals are destroyed, too. If man continues to cut down rainforests, more than one million species of plants and animals will become extinct by the byear 2030!


2)Degree of destruction:

Originally 8 million square miles of tropical rainforest encircled planet. More than half has been burned and bulldozed. Now only 3,4 million square miles remain. Over last decade, man destroyed 113 million acres of rainforest. In 2 hours, modern machinery can clear 900 tons of rainforest. That mean, that every second humans wipe out a area of rainforest the size of two football fields. For example: since 1950, man has destroyed Costa Rica’s rainforests at the average rate of 300 to 500 square kilometres per year. Two-thirds of Central American rainforests have allready disappeared. The largest cause of rainforest destruction is commercial logging. The current rate of rainforest destruction indicates a potential loss of 5 to 15 % of the world’s animal species. Between 1990 and 2020, estimates indicate that at lest 100 animal species could be lost each day! Rainforest destruction is the single largest cause of species extinction. If these current rates of destruction continue, scientists predict that 80 to 90% of Earth’s tropical rainforests will be decimated by the year 2020.


3)Effects of deforestation:

On the Water:
Rainforests absorb nearly half of the Earth’s rainfall and gradually release it into rivers and streams. The tropical forests release rainwater into watersheds slowly and evenly. Preventing both flooding and droughts. Therefore, when rainforests are intact, the rivers run full and clear. However, when the forests are destroyed, the rivers dry up and become muddy.
 
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