Category Science

Why is deforestation damaging the world’s ecology?

                    The world’s tropical rainforests are being lost at an alarming rate, and already the effects of this loss can be seen. Rainforest trees are cut down to provide timber as well as land for grazing and raising crops, The remaining scrub and branches are usually burned, providing a rich source of fertilizer for one or two years, Then the land becomes barren. Rainfall washes away the topsoil, leaving bare rock in which very little grows.

                    The results of deforestation are seen in countries such as Bangladesh, where heavy rains are no longer soaked up by the forests in the foothills of the Himalayas. Instead the rainwater sweeps down the valleys, causing enormous flooding and loss of life.

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What is the main crop grown on the prairies?

                     The prairies in Canada and the USA are enormous grassy plains, which were once the home of huge herds of buffalo.

                    Today the prairies are covered with enormous fields of maize, supplying most of the world’s needs for this important food crop. The agriculture here is true factory farming, where the crops are planted, treated and harvested with vast machines and using very little manual labour.

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Which are the main plants grown as crops?

                        About 150 types of plant are regularly cultivated as food crops, although thousands more are eaten in local areas. The Most important crops are cereals (grass- like plants), especially maize, rice and wheat. Root crops such as potatoes are commonly grown in temperate climates, and sweet potatoes, yams and cassava are grown in tropical parts. The seeds of the pea family, known as pulses, include beans, soy beans, chickpeas and lentils. They are a particularly valuable source of protein, especially in some parts of the world where meat is in short supply and malnutrition may be commonly encountered.

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What lives on coral reefs?

                   Coral reefs are the marine equivalent of rainforests. They are home to huge numbers of a great variety of animals. Unlike some other habitats, few plants grow on coral reefs because fish and sea snails graze them. Ocean currents carry most of the food to the reef. Plankton is the basic food that powers the whole reef system. The small animals that feed on plankton are eaten by large crustaceans and fish, and so on up the food chain to predators such as sharks.

                 If a coral reef continues to grow it may begin to rise out of the water, becoming a coral island. The sea helps to break up the coral growths and pile them up. Creatures such as calcifying algae cement the pieces together to form a solid structure. If soil lodges in the coral vegetation often begins to grow on the surface. Many of the Pacific islands were formed in this way.

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What lives in deciduous forests?

                         Temperate forests contain far more varieties of trees and shrubs than are found in conifer forests. Because the shade in these forests is not so great, there is far more undergrowth and larger clearings between the trees. During the lifetime of a tree such as the oak, large branches fall off and rot on the forest floor, providing a rich habitat for fungi and small animals. Other fungi live naturally in association with tree roots, and their mushrooms are eaten by mice and squirrels. Foxes are common predators in temperate forests. Deer graze in the clearings and feed on young trees. Many types of small seed-eating bird live in temperate forests, hunted by predators such as hawks.

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What lives in tropical rainforests?

 

                    Tropical rainforests contain the most varied mixtures of animals and plants of any habitat on the Earth. They contain large and small predators and a bewildering variety of birds. All these animals are supported by huge numbers of trees that produce fruit to feed them and their prey all year round. Because there is no true winter in tropical rainforests, there is no need for the cycle of eating and storing food that takes place in cooler climates.

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