The destruction of rainforests

Pre-reading

With a partner, consider the following questions and try to answer them Then quickly scan the opening paragraph of the chapter to check your answers.

1. Where are the rainforests in the world?

2. Where are the largest rainforests found?

3. If the present trend of destroying the rainforests continues, how long do you think it will take to destroy them all?

The tropical rainforests surround the equator of the earth like a belt. They occupy a total area of about nine million square kilometers. The largest rain­forests are in South America, particularly the Amazon forest in Brazil which stretches to Peru, Ecuador, Colombia, Venezuela and French Guyana. Smaller forests are found in tropical Asia and central Africa. The rainforests are rap­idly being cut down. Nobody knows exactly how much is cut down every year. Estimates vary between 100,000 and 400,000 square kilometers. Bra­zil alone lost about48,000 square kilometers of rainforest in 1990. The tropical forests of west Africa (Nigeria and the Ivory Coast) have almost disappeared over the past 40 years. According to the most conservative estimate, all the rainforests in the world will be gone in less than a century unless the rate of felling slows down. A more realistic estimate is 30 years.

Why are people cutting down the rainforests? Between 10 and 30 per­cent of the trees are sold as logs to the timber trade. Most of the trees from the Nigerian rainforests were sold to the timber industry in Japan, the United States and other industrialized countries. Tropical hardwoods such as ma­hogany are strong, attractive and hardwearing. They are used in rich coun­tries to make luxury furniture, doors and window frames. But much of the wood is not made into durable products. It is made into cheap, throwaway goods. A large proportion of the hardwood imported into Japan in recent years has been made into plywood, paper or chopsticks. The destruction of rainforests for the timber trade sometimes involves political corruption. In many developing countries, a person must get a license from the govern­ment before he can cut down trees. A license to cut down trees is almost a license to print money. Government officials sometimes give out these li­censes to members of their own families or in return for "favors" from business people. In the countries where this kind of corruption occurs, poli­ticians will be reluctant to restrict the activity of timber traders.

The multinational timber companies often make roads deep into the for­ests so that they can drag the logs away. They may only cut down a few

trees themselves, but their roads make the forests accessible to local peas­ant farmers. These farmers cut down trees to create new cropland, or even simply for fuel. It is a great, tragedy that large areas of the Amazon rainfor­ests have been wasted as firewood! Tree felling for firewood is also a prob­lem in the temperate forests. Over 85 percent of all the wood cut in the Third World (hardwood and softwood) is used for fuel. Wood provides more energy in the developing world today than the total energy from fossil fuels, nuclear fuels and alternative energy sources.

The largest cause of the destruction of rainforests is probably the crea­tion of grazing land to feed cattle. The growth of the fast food industry in the 1970s created a demand for cheap beef for making hamburgers. In the late 1970s, in return for a large loan from the international banks, the Costa Rican government removed thousands of hectares of rainforest by the infa­mous slash-and-burn technique to provide grazing land for export cattle. Oilier countries soon saw the profit they could make from cattle farming and began to cut down their own rainforests. According to one estimate, half of the world's rainforests have already been cut down to make space for the meat industry, and approximately half a metric ton of vegetation is destroyed for every hamburger eaten.

Why do we need to conserve the rainforests? First, because the rainfor­ests are the lungs of the world. They take in carbon dioxide and give out oxygen by photosynthesis:

C02 + H20 + light energy—> CHO + 02 carbon + water + sunlight —> carbohydrate + oxygen dioxide The loss of vegetation in the rainforests magnifies the greenhouse effect. We are producing more arid more carbon dioxide from burning fossil fuels. The capacity of the rainforests to absorb this environmentally toxic gas is becoming ever more crucial. Second, the rainforests are the world's most important means of storing water. The trees soak up water in the rainy season and slowly release it into the ground and rivers. This protects the fragile soils from the potentially devastating effects of tropical storms. The rainforests supply water to the rivers during the dry season. If they did not do this, many rivers would disappear in the dry season and become raging torrents in the rainy season, flooding the nearby fields and washing away the soil.

Third, the rainforests control the climate. Seventy-five percent of the rain that falls on the tropical rainforests enters the trees from the soil by transpiration and then evaporates from the surface of the leaves. (The other 25 percent of the rainwater stays in the soil and enters the rivers as run-off). These two processes are known together as "evapotranspiration." The heat energy required to evaporate the water from the forests cools the equato­rial regions. The clouds formed by the water vapor also cool the land by reflecting solar radiation back into space. These clouds are carried to cooler parts of the earth by natural convection, where they release warm rain which raises the temperature hi these areas. If the rainforests disappear, so will the rain. Without the rainforests, the temperature difference between the tropics and the temperate zones would be far greater.

Fourth, the rainforests are a reservoir of micronutrients. Tropical rain­forests usually grow on poor soil. Most of the essential nutrients are stored not in the soil but within the trees themselves. The roots of the trees, which make up about 60 percent of their mass, do not grow deep into the soil. They spread out and form a thick network a few meters beneath the sur­face. These shallow roots absorb free nutrients released from the thick layer of decaying vegetation on the forest floor. Recycling of these nutrients is crucial to the survival of the ecosystem that the rainforests support. When the trees are cut down, vital nutrients are washed away with the run-off and a whole ecosystem quickly dies.

Fifth, the rainforests, and the ecosystems that they support, are an im­portant source of raw materials for many different industries. They sup­ply us with hundreds of useful products — from rubber to peanuts. One very important benefit is the supply of medicinal plants. About 80 percent of all traditional herbal medicines and 25 percent of modem Western medi­cines are extracted from plants that grow in the rainforests. We do not know how many more important medicines are lying undiscovered within the rainforests. Scientists and ecologists are working together in this im­portant branch of medical research. Loss of plant species within the rain­forests will mean that many lifesaving drugs will never be discovered. One last — and very important — reason for conserving the rainforests is that they are the home of several million people, win-still live in primitive tribal societies within the forests. We have both a moral and a scientific duty to protect the homelands of these unique and fascinating societies. The rain­forest tribes have an intimate knowledge of the many thousands of plants and animals that live there. They can show us how to use these plants and animals for new sources of food, medicines and building materials. The tribal people are more than an anthropological curiosity. They are the key to the living resources of the rainforests.

EXERCISES

Summary Writing

How many reasons does the author give for conserving the rain­forests? What are they? Check the answers you noted with the ones in the following four sentences. Finally, rearrange and write out the four sentences so that they form a summary of the points given in the chapter.

1. Moreover, one other benefit relates to the supply of many raw materi­als, products and medicinal plants.

2. Finally, the homes of millions of people are to be found in the rainfor­ests and this homeland should be protected for moral and scientific reasons.

3. They act as the lungs and watersheds of the world, they control the climate and are a reservoir of micronutrients.

4. There are a number of reasons why the rainforests should be conserved.