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Unlock This CourseDeforestation means clearing forest on a large scale so the land can be used for something else. Forests are being cleared in many parts of the world, but the biggest losses are in tropical rainforests such as the Amazon. Forests do not disappear for just one reason. People want wood, food, minerals, roads, homes and electricity, and each of these needs land that is covered in trees. The spec names six causes you must know.
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Companies cut valuable trees, such as mahogany, to sell as timber for furniture and building. Machines and trucks cut and carry out many trees quickly. Other trees are knocked down too when heavy machines make tracks through the forest.
Large areas are cleared for cattle ranches and for crops such as soya beans and palm oil. Small farmers also clear plots to grow food. Burning the trees is the cheapest way to clear the land.
Mines are dug in the forest to reach metals and minerals. The trees above the minerals are cleared, and more are cleared for roads, machinery and workers' camps.
Roads and railways are cut through forest so that timber, crops and minerals can be taken out. Land beside a new road is cleared for farms and homes.
As towns grow, and as people move into the forest to find work or land, trees are cleared for houses, shops and fields.
A dam holds back a river and floods the valley behind it, so the trees in that area are drowned or cleared first. Roads and power lines for the dam also need forest cleared.
Remember from the Timber Resources lesson that wood is a valuable ecosystem good. Deforestation happens when it is taken faster than the forest can recover.
The causes feed each other. A new road is built to reach a mine. Loggers use the road to reach more trees. Farmers follow the loggers and burn the cleared land. Families settle beside the road, and the town grows. A dam then needs more roads and power lines. Roads are the key link, because they open up forest that was once too far away to reach.
The best answers do not just list causes. They say how one leads to another, for example "a new road gives loggers and farmers access to the forest, so more trees are cleared".
The spec asks you to use maps to identify the pattern of deforestation. Maps can be satellite images, or maps that show forest in green and cleared land in another colour. Look for the shape and place of the cleared land. Here is an imaginary example. It is not real data.
An imaginary map shows green forest. A main road runs from east to west across the middle. Short side roads branch off it to the north and south, like the bones of a fish. Cleared land, shown in brown, lies in strips along every road. The north-west corner is unbroken forest. A grey patch near the top of the map is labelled "mine", with cleared land all around it, and a blue lake behind a dam is labelled in the south-east.
The cleared land is not spread evenly. It is close to the roads, in a fishbone pattern, and it spreads out from the road edges. The forest furthest from the roads is mostly untouched. This shows that roads give access and so lead to deforestation.
Question: Describe the pattern of deforestation shown on the map. [3 marks]
Step 1: say where it is. "Cleared land is found next to the roads."
Step 2: say what shape it makes. "It forms a fishbone pattern, with strips along the main road and the side roads."
Step 3: say where there is none, and use the map. "The forest far from the roads, in the north-west corner, is mostly uncleared. Cleared land also surrounds the mine."
(a) Explain how mining can lead to deforestation. [3 marks]
(b) Explain why building new roads increases deforestation. [3 marks]
(a) Trees are cleared from the land above the minerals so the mine can be dug (1). More forest is cleared for roads, machines and workers' camps (1). Settlements grow around the mine, so even more trees are cut down (1).
(b) Roads give access to parts of the forest that were once too far away to reach (1). Loggers can cut trees and drive them out by truck (1). Farmers and settlers clear the land beside the road, so deforestation spreads outwards from it (1).
In a "Describe the pattern" map question, say where the cleared land is, give its shape, and mention a gap or exception, using at least two details from the map.