Unit 2 Tropical rainforests are shrinking Unit 2

Unit 2 Tropical rainforests are shrinking

Unit 2 Tropical rainforests are shrinking What is deforestation? A lot of tropical rainforests have been cleared for farming and forest resources.

Unit 2 Tropical rainforests are shrinking What is deforestation? The world’s tropical rainforests are rapidly shrinking. In countries like the Philippines, Thailand Malaysia, rainforests no longer remain in the lowlands or on the lower slopes of mountains.

Unit 2 Tropical rainforests are shrinking What is deforestation? Africa South America and Caribbean 55 85 60 Source : FAO (1997) Asia and Oceania

Unit 2 Tropical rainforests are shrinking What is deforestation? An area about the size of two football fields is being destroyed every second! There were originally 16 million km² of tropical rainforests covering the earth, but today less than half remain. The World Resources Institute has estimated that TRFs are being cleared at a rate of 61 000 km² a year. If this rate of clearance continues, there will be no more tropical

Unit 2 Tropical rainforests are shrinking What is deforestation?

Unit 2 Tropical rainforests are shrinking Why are the rainforests being destroyed? For Farming Some natives living in tropical rainforests practise shifting cultivation.

Unit 2 Tropical rainforests are shrinking Why are the rainforests being destroyed? For Farming In shifting cultivation, a patch of land is cultivated for a short period, then left fallow for several years while the shifting cultivator moves on to work on another piece of land.

Unit 2 Tropical rainforests are shrinking Why are the rainforests being destroyed? For Farming As the population increases, more forests have to be cleared for farming. The United Nations Food and Agricultural Organization estimates that about 250 million shifting cultivators are using the slash and burn method which destroys 50 000 km² of tropical rainforests a year.

Unit 2 Tropical rainforests are shrinking Why are the rainforests being destroyed? For Plantation Farming Tropical rainforests are cleared and turned into plantations for the growing of commercial crops such as tea, coffee, rubber and oil palm.

Unit 2 Tropical rainforests are shrinking Why are the rainforests being destroyed? For Plantation Farming These products are exported for earning foreign exchange. In many parts of Malaysia, rubber and oil palm plantations have replaced rainforests.

Unit 2 Tropical rainforests are shrinking Why are the rainforests being destroyed? For Cattle Ranch In Central America and in the Amazon Basin rainforests are cleared and turned into cattle ranches for the rearing of beef cattle.

Unit 2 Tropical rainforests are shrinking Why are the rainforests being destroyed? For Minerals Tropical rainforests are rich in minerals, the extraction of minerals have lead to the destruction of tropical rain forest.

Unit 2 Tropical rainforests are shrinking Why are the rainforests being destroyed? For Timber Commercial logging for timber is another cause of the destruction of rainforests.

Unit 2 Tropical rainforests are shrinking Why are the rainforests being destroyed? For Timber The export of valuable hardwoods is a major source of income for many developing countries in the tropical regions. The valuable hardwoods include teak and mahogany. High quality hardwood costs as much as US$ 900/m³.

Unit 2 Tropical rainforests are shrinking World trade of tropical timber N Europe To North America Asia Japan N. e ri Am e ri ca Amazon Congo an N. 35% S. E. Asia To Europe South America km 40% ca To 7% 13% T o Ja p Am Africa Australasia Tropical rainforest Export of tropical timber

Unit 2 Tropical rainforests are shrinking Why are the rainforests being destroyed? For Firewood The United Nations estimates that 60% of the world population depends on firewood for cooking and heating. In 1980, 180 million people in Africa faced a serious shortage of firewood.

Unit 2 Tropical rainforests are shrinking Why are the rainforests being destroyed? For Development Projects The development of towns, the mining of minerals, the building of dams and hydro-electricity projects are all eating away our tropical rainforests.

Unit 2 Tropical rainforests are shrinking Why are the rainforests being destroyed? For Resettlement As the population of these tropical rainforest regions increases, their governments are carrying out resettlement schemes by encouraging city people to settle in rainforests.

Unit 2 Tropical rainforests are shrinking Why are the rainforests being destroyed? For Resettlement In Indonesia the government has resettled millions of people from the densely populated Java to nearby islands such as Sumatra, Borneo, Sulawesi and Irian Jaya. N ma Su Borneo Halmahera tra Sulawesi Ceram Java km Bali Flores Irian Java

Unit 2 Tropical rainforests are shrinking Why are tropical rainforests important? Rich in wildlife Tropical rainforests contain the greatest variety of wildlife species on earth. Tropical rainforests provide habitat for at least 5 million species of plants and animals.

Unit 2 Tropical rainforests are shrinking Why are tropical rainforests important? Supplying forest resources Tropical rainforests are rich in natural resources. We obtain foodstuffs, fruits, timber, industrial raw materials and medicines from the rainforests. Industrial raw materials obtained from the forests include hardwood timber, rubber, oils, resins, rattan, bamboo, pesticides, waxes and dyes. Quinine is used in treating malaria is obtained from a cinchona tree in tropical rainforests.

Unit 2 Tropical rainforests are shrinking Materials from tropical rainforests Firewood Furniture Building material Minerals Paper Food Tropical rainforests Pesticides Rubber Dyes and resins Medicines

Unit 2 Tropical rainforests are shrinking Why are tropical rainforests important? Regulating air, water and soil Rainforests play a very important role in regulating and regenerating the world’s air, water and soil. The dense forests absorb carbon dioxide and give back oxygen to the air. They recycle water back into the atmosphere through evapotranspiration.

Unit 2 Tropical rainforests are shrinking Why are tropical rainforests important? Protecting the soil The dense vegetation protects the soils under it from the attack of rain and the heating of the sun. It also helps regenerate soil nutrients. Plant litter breaks down quickly and nutrients are returned to the soil.

Unit 2 Tropical rainforests are shrinking How trees regulate and regenerate air, water and soil? Tr a ns Evapotranspiration returns water to the atmosphere Evaporation Gives off oxygen pi ra tio n Takes in carbon dioxide Protects land from rain and heating of the sun Plant litter breaks down quickly and nutrients return to soil Roots: 1) absorb rainwater and prevent flooding 2) bind soil together and check erosion

Unit 2 Tropical rainforests are shrinking What are the effects of deforestation? Natives lose their homelands If the forests are removed, the natives would lose their homelands and they would not be able to maintain their lifestyles and cultures.

Unit 2 Tropical rainforests are shrinking What are the effects of deforestation? Loss of wildlife Gone will be the millions of species of plants and animals, many of which are unknown to us and have never been recorded. With the present rate of forest clearance, 750 000 species will disappear by the beginning of the 21 st century.

Unit 2 Tropical rainforests are shrinking What are the effects of deforestation? Loss of forest resources Tropical rainforests contain very valuable resources. With deforestation, the supply of forest products and raw materials will end. The valuable hardwood timber will disappear.

Unit 2 Tropical rainforests are shrinking What are the effects of deforestation? Change in climate With the rainforests gone, the water cycle is interrupted as evaporation and transpiration are reduced. The burning of rainforests pumps 3 to 6 billion tonnes of carbon dioxide into the atmosphere each year. These gases trap the heat and cause a rise in world temperature. Rise in temperature Less rain

Unit 2 Tropical rainforests are shrinking What are the effects of deforestation? Soil erosion When the land is no longer protected by a forest cover soil erosion occurs. Large channels on the ground surface called gullies are cut out by rain. The land is no longer fertile for farming as the nutrients in the soil are washed away.

Unit 2 Tropical rainforests are shrinking What are the effects of deforestation? Soil erosion Rain washes away surface soil into rivers which blocks the river channels. When heavy rain falls flooding occurs as there is no more soil or vegetation to absorb rainwater. Unprotected land. Soil washed into river

Unit 2 Tropical rainforests are shrinking The activities in tropical rainforests National Park Cutting trees for firewood Field abandoned by shifting cultivators Village Farmland Rice fields Copper mine Cattle ranch Rubber trees Animals for sale New trees planted Logging permitted by government Road Logs Export

Unit 2 Tropical rainforests are shrinking Terms to learn Deforestation (濫伐林木) 濫伐林木 - the clearance of forests for farming and forest resources. Commercial logging (商業伐木) 商業伐木 - trees are cut down and the timber obtained is sold for cash. Resettlement scheme (人口徙置計劃) 人口徙置計劃 - a plan of sending people from densely populated areas to live in sparsely populated areas.

Unit 2 Tropical rainforests are shrinking Terms to learn Evapotranspiration (蒸散) 蒸散 - the loss of water through evaporation of water in soil and transpiration of plants.