B. Read carefully this extract about rainforests and write down its defining characteristics

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1 A. What do you already know about rainforests? 1. What is a rainforest? 2. Where in the world can we find rainforests? 3. Why are rainforests important? 4. What sort of products can we get from them? 5. Why should we care about them? 6. Why are them so fragile? 7. Do you know any other type of forest? B. Read carefully this extract about rainforests and write down its defining characteristics Rainforests are defined primarily by two factors: location and amount of rainfall they receive. Rainforests receive from 4 to 8 meters of rain a year -- 5 meters of rain falls on the rainforests of Borneo each year, five times as much as on the state of New York. The heavy vegetation blocks the rainfall, and water reaches the forest floor by rolling down branches and trunks or as a fine spray. Another distinctive characteristic is that rainforests have no "seasonality" -- no dry or cold season of slower growth. C. Find the blackened words in text D that fit into the definition The ground with respect to its composition, quality, etc., or as the source of vegetation. A naturally level space or extended surface. Also, the ground The action, process or manner of growing; vegetative development; increase. the determination or statement of an arithmetical mean; a medial estimate A woody plant smaller than a tree A class of the animal kingdom the members of which are characterized by the possession of mammæ in which milk is secreted for the nourishment of the young. Having leaves; clothed with leaves or foliage; made or consisting of leaves. One of a large group of vascular cryptogamous plants constituting the N.O. Filices The popular name of several animals which feed upon ants (and termites). Something which is laid. The trailing or climbing plant, also generally, any plant of the genus Vitis. In a great degree; greatly, considerably, very much, a great deal. 1

2 D. Label this diagram according to the information provided in the text The forest floor has poor soil. Mainly insects live on this layer, although large mammals like gorillas and jaguars are also found there. Many smaller animals, including anteaters, lemurs, and tree kangaroos live in the understory. This is also where many small trees and shrubs are found. It is a dark, cool environment that is under the leaves but over the ground. Most of the understory of a rainforest has so little light that plant growth is limited. There are short, leafy, mostly non-flowering shrubs, small trees, ferns, and vines (lianas) that have adapted to filtered light and poor soil. The canopy, or top layer, is made up of the tops of trees which can grow to be over 200 feet high. Many tropical birds, monkeys, apes, snakes, and other animals live in the canopy. Finally, we can find the emergents, the tops of the tallest trees, which are much higher than the average trees. 2

3 ! " # $ #% $ #" $"# &$ &' ( This region was once entirely covered with rainforest, but large areas have been cleared for cattle ranching and for sugar cane plantations. Like other major rainforests, the jungles and mangrove swamps of Central America contain many plants and animals found nowhere else. Central America is famous for its large number of tropical birds, including many kinds of parrots. The Amazon jungle is the world's largest tropical rainforest. The forest covers the basin of the Amazon, the world's second longest river. The Amazon is home to the greatest variety of plants and animals on Earth. A 1/5 of all the world's plants and birds and about 1/10 of all mammal species are found there. Central Africa holds the world's second largest rainforest. To the south east, the large island of Madagascar was once intensively forested, but now much of it is gone. Africa contains areas of high cloud forest, mangrove swamps and flooded forests. The island of Madagascar is home to many unique plants and animals not found anywhere else. The rainforests of Asia stretch from India and Burma in the west to Malaysia and the islands of Java and Borneo in the east. Bangladesh has the largest area of mangrove forests in the world. In Southeast Asia the climate is hot and humid all year round. In the mainland Asia it has a subtropical climate with torrential monsoon rains followed by a drier period. Millions of years ago, Australia, New Zealand and the island of New Guinea formed part of a great forested southern continent, isolated from the rest of the world. Today these countries contain many different species of animal that occur nowhere else. Undergrowth in Australia's tropical forests is dense and lush. The forests lie in the path of wet winds blowing in from the Pacific. The largest contiguous coastal temperate rain forest traces the northwestern maritime margin of North America, from Kodiak Island in Alaska south through British Columbia and the U.S. Pacific Northwest to California's "fogbelt" redwoods. Elsewhere in the north, Norway contains small fragments of coastal rain forest, and scientists speculate that Japan may have some areas of rain forest as well. The forests formerly found along the west coasts of Ireland and Scotland, parts of Iceland, and in a narrow crescent along the eastern shore of the Black Sea are long gone. Chile contains the Southern Hemisphere's largest remaining coastal temperate rain forest. Significant areas of coastal rain forest also stand on the west coast of New Zealand's South Island and on the Australian island of Tasmania, where broadleaved rain forests harbor the most ancient constituents of the Australian flora. )%*% +%, $ $ $ #% -%, $ &' &# # % 3

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5 F. Guessing the meaning of words using the inmediate context. Writers often use certain strategies to help the reader understand unknown words or expressions. One of them is explaning these words by means of a synonym, a short definition or related word. Have a look at this example taken from the text below: Scientists divide rainforests into different strata (or layers) for easy reference. It is quite simple to infere that strata and layer are either synonyms or related words. The use of or makes the deduction easier. Now read carefully the following text and work out the meaning of these words: Emergents, scarlet macaw, canopy, hornbill, howler monkey, lizards, epiphytes, vines, beetle, kinkajou. RAINFOREST STRATA "Strata" means "layers." Scientists divide rainforests into different strata (or layers) for easy reference. Each of these layers is a very different environment and supports different life forms. These strata differ in many ways, including temperature, the amount of sunlight that they receive, the wetness of the environment, and the amount and types of life forms living in it. The emergents consist of the tops of the tallest trees, which are much higher than the average canopy height (ranging up to 270 feet or 81 m). It houses many birds (like the scarlet macaw), insects, and more. The canopy is the name given to the upper parts of the trees (about 65 to 130 feet or 20 to 40 m tall). This leafy environment is full of life: insects, arachnids, many birds (like the keel-billed toucan, the scarlet macaw, the cuckoo, and the hornbill), mammals (like the howler monkey, which is the second-loudest animal in the world, and the orangutan), reptiles (like snakes and lizards), and others. Plants in the canopy include thick, snake-like vines and epiphytes ("air plants") like mosses, lichens, and orchids (which grow on trees). The understory is a dark, cool environment that is under the leaves but over the ground. Most of the understory of a rainforest has so little light that plant growth is limited. There are short, leafy, mostly non-flowering shrubs, small trees, ferns, and vines (lianas) that have adapted to filtered light and poor soil. Some of these plants include ferns, palms, philodendrons, and heliconias. Animals in the understory include insects (like beetles and bees), arachnids, snakes, lizards, and small mammals (like the kinkajou) that live on and in tree bark. Some birds (like antbirds) live and nest within tree recesses and eat the abundant insects. Some larger animals, like jaguars, spend a lot of time on branches in the understory, surveying the area, looking for prey. The floor of the forest is teeming with animal life, especially insects and arachnids (like tarantulas). The largest animals in the rainforest generally live here, including gorillas, anteaters, wild boars, tapirs, jaguars, and people. 5

6 Now answer these questions on the meaning of words. 1. What factors make the strata different? 2. What is the name of the lowest of the strata of the rainforest? 3. What is the name of the next layer, the dark, cool zone above the ground but under the leaves? 4. What is the name of the rainforest stratum that includes leafy tree environments and the tree tops? 5. What is the name of the rainforest stratum that includes only the tallest tree tops that occasionally tower over the remaining forest? 6. Name two rainforest strata that receive the most sunlight. 7. Name two rainforest strata that receive the least sunlight. 8. In which rain forest layer do most of the large animals live? 9. In which rain forest layer do many birds, like the toucan, live? 10. Which is the tallest rain forest zone? 6

7 Tropical Rainforest Plants Plant Adaptations Bark In drier, temperate deciduous forests a thick bark helps to limit moisture evaporation from the tree's trunk. Since this is not a concern in the high humidity of tropical rainforests, most trees have a thin, smooth bark. The smoothness of the bark may also make it difficult for other plants to grow on their surface. The bark of most trees looks very similar. This similarity is very frustrating for botanist-it makes trees more difficult to identify in the rainforest. Lianas Lianas are climbing woody vines that festoon rainforest trees. They have adapted to life in the rainforest by having their roots in the ground and climbing high into the tree canopy to reach available sunlight Drip Tips Pachystachys sp. The leaves of forest trees have adapted to cope with exceptionally high rainfall. Whichever way you look in a tropical rainforest most leaves look very similar and have a drip tip. It is thought that these drip tips enable rain drops to run off quickly. Buttresses Many large trees have massive ridges near the base that can rise 30 feet high before blending into the trunk. Why do they form? No one knows for sure, but buttresses may help transport water, increase the surface area for oxygen and carbon dioxide exchange, or provide greater stability. Prop and Stilt Roots Prop and stilt roots help give support and are characteristic of tropical palms growing in shallow, wet soils. Although the tree grows fairly slowly, these above-ground roots can grow 28 inches a month. Epiphytes Epiphytes are plants that live on the surface of other plants, especially the trunk and branches. They grow on trees to take advantage of the sunlight in the canopy. Most are orchids, bromeliads, ferns, and Philodendron relatives. Tiny plants called epiphylls, mostly mosses, liverworts and lichens, live on the surface of leaves. Bromeliads Neoregelia sp. Bromeliads are found almost exclusively in the Americas. Some grow in the ground, like pineapple, but most species grow on the branches of trees. Their leaves form a vase or tank that holds water. Small roots anchor plants to supporting branches, and their broad leaf bases form a water-holding tank or cup. The tank's capacity ranges from half a pint to 12 gallons or more. The tanks support a thriving eco-system of bacteria, protozoa, tiny crustaceans, mosquito and dragonfly larvae, tadpoles, birds, salamanders and frogs. Mangroves On tropical deltas and along ocean edges and river estuaries, trees have adapted to living in wet, marshy conditions. These trees, called mangroves, have wide-spreading stilt roots that support the trees in the tidal mud and trap nutritious organic matter. Nepenthes Nepenthes sp. Pitcher plant vines in the family Nepenthaceae have leaves that form a pitcher, complete with a lid. Sweet or foul-smelling nectar in the pitcher attracts insects, especially ants and flies, that lose their grip on the slick sides and fall into the liquid. Downward-pointing hairs inside the pitcher prevent the insects'escape. Pitcher plants are not epiphytes but climbers rooted in the soil. 7

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11 ./ Why are Rainforests important? 1. Read each section and mark the sentences below as true or false. If false provide the right one. Tropical forests cover only twelve percent of the land-area of the Earth, yet they are home to between 50 and 90 percent of the world's species. Because of tropical deforestation, at least one species is disappearing every day. This rate of extinction is now 400 times faster than at any other period in the history of the planet. a. Tropical Rainforests (TRF) house the highest number of species in the world. b. Only 30 species disappear every month. c. Nowadays in the TRF, more species become extinct than ever before Rainforests are a vital source of medicines. Today, less than 1 percent of the worlds tropical forest plants have been tested for pharmaceutical properties, yet a quarter of all modern medicines came originally from rainforests. Most were first discovered and used by indigenous people. a. TRF countries produce a lot of medicines b. Modern chemical companies were the first to use the medicinal properties of some TRF plants. c. Most TRF plants are known for their medicinal properties. Rainforests also offer a bounty of foods. Foods that we use today which originated in rainforests include coffee, cocoa, many fruits and nuts, spices, rice, and other products such as rubber, gums, resins, dyes, tannins and cane. Of an estimated 75,000 edible plants found in nature, only 150 enter world commerce and only 20 (mostly domesticated cereals) stand between human society and starvation. This makes modern agriculture extremely vulnerable to pests, diseases and changes in climate. Genes from wild plants can be used to fortify modern varieties against this vulnerability. Without rainforests, this opportunity is lost, as is the chance to develop entirely new food plants. a. Many edible plants we eat today originally came from TRF. b. TRF offer a genetic bank of plant species which may help modern species to better adapt to new situations. c. Most edible plants enter world commerce. d. TRF are home of many edible plants we do not know yet. Tropical forests regulate global and regional climate-systems by acting as heat and water pumps. They release moisture into the atmosphere which returns to the ground as rain. When the forest is cleared, the water cycle is disrupted, temperatures increase, droughts become common, and eventually deserts may form. For example, the drought in the Sahelian belt (south of the Saharah Desert), has been attributed to deforestation in West Africa. Estimates suggest that tropical deforestation currently contributes at least 19% of greenhouse gas emissions. Tropical forests have been described as "the lungs of the Earth". However in mature primary forest, storage and release of carbon is in balance. Carbon-dioxide consumed during photosynthesis is equalled by that released when organic matter decays. A standing forest acts as a store or sink of carbon. On the other hand, when forests are burned or logged and the debris left to decay, carbon dioxide is released into the atmosphere. 11

12 a. TRF regulate global climate by releasing water to the atmosphere. b. TRF are important because they help to reduce greenhouse gas emissions. c. TRF store more carbon than they release. d. During photosynthesis TRF trees release CO2. e. When TRF are cleared, the temperature increases because of a lack of water. f. Deforestation may be carried out (circle the right answers and erase the wrong ones) by : Burning increasing standing logging clearing g. Drought is (mark the right answer): g.1. The lack (absence) of water. g.2. The increase in temperature. g.3. The disruption of the hydrological cycle. h. The deforestation of the Sahel caused their water problems. Tropical rainforest soils are very old and have been impoverished by eons of high rainfall leaching away their mineral nutrients. The forests have evolved to cope with this by rapidly recycling nutrients. Forest litter, and the droppings and remains of animals are quickly decomposed, releasing nutrients for uptake. Most nutrients are only available from this decomposing layer, so many rainforest trees are shallowrooting and have buttresses for support. Rainforests act like giant sponges, soaking up moisture, and then releasing it slowly. This moderates the flow of rivers thus preventing flooding and ensures that rivers and creeks continue to flow during periods of lower rainfall. When the forest is cleared, rain falls directly onto the compacted soil, often resulting in serious soilerosion, siltation and flooding. Major floods in southern Thailand, Bangladesh and the Philippines have been attributed to forest clearance. Once the nutrient recycling-system is broken down, the land can't support human activities such as cattle ranching for more than a few short years. 1. TRF soil is very rich in nutrients. 2. TRF soils are very poor in nutrients because rainwater takes them away. 3. TRF trees have adapted to this situation by the use of shallow roots and buttresses. 4. The decomposition rate in TRF is faster than in other type of forests. 5. All nutrients are in the decomposing layers. 6. Flooding is: a. The clearance of trees. b. The inundation of land c. Higher rainfall 7. Siltation, erosion and flooding are a consequence of deforestation. Scientists now say that the rainforest ecosystem in the Brazilian Amazon is a net absorber of carbone dioxide, and therefore helps to protect the earth against the greenhouse effect. This means that primary forests may be more important as carbon sinks than either young secondary forests or plantations. Over the past few years, the forest industry has argued that plantations are needed to absorb carbon dioxide, and plantations are still being established in place of natural forests in countries such as Indonesia and Chile. a. Natural forests store higher amounts of CO2 than plantations. b. TRF absorb CO2 and help to reduce the greenhouse effect. 12

13 2. Provide heading for the different sections of the text. Each heading should correspond to a reason of the importance of TRF. 3. Organise the above reasons under general headings Economic Cultural Social Biological Environmental Political 4. Reading. Check the following text for reasons to preserve TRF. Rain forests are complex ecosystems that are essentially self-sufficient when healthy. However, they are not easily regenerated once removed from an area. A healthy rain forest will, for instance, thrive by recycling most of the nutrients needed for plant growth between living plants, animals and decaying organic matter without outside intervention; however, it needs a large variety of organisms to do this. Once a parcel is deforested, it is unlikely that it will regrow to resemble its past condition without massive human intervention (which rarely occurs). In its place will likely grow a low-species- diversity 13

14 assemblage of organisms that will eventually deplete the landscape of nutrients and therefore not be truly sustainable. Thus, rainforest loss is typically permanent. The global coverage by rain forests is dimished each year by human activities in order to support things such as agriculture, mineral resource exploitation, the hardwood lumber industry and urbanization. There are a number of physical, biological and ascethic reasons to preserve rain forests. When not preserved, the effects on people can be both local and global in scope. A few are summarized below: Rain forests exist in regions that are very wet. Both tropical and temperate climate examples can be found. A primary useful attribute of rain forests is that they control the rate of erosion in their watersheds. These forests disperse the energy of falling heavy rain and further reinforce the soil through their root system. Without such forests, fully-formed top soils would not be generated and instead, weathered and/or fresh rock would appear on the surface. Without soils, the large arrays of organisms that require it to live would not exist, nor would the fundamental chemical processes that occur in a healthy ecosystem take place. In addition, right after deforetation and possibly continuing for many decades hence, massive transport of soil and sediment particles occurs in waterways in the area, thus impacting aquatic ecosystems as well. Soil particles can contain high amounts of chemically-reactive substances and plant fertilizer ("nutrient") compounds; dispersing them into the environment in quick pulses can overwhelm an aqautic environment, causing such problems as "eutrophication" (the biological diminishment of dissolved oxygen below levels acceptable to most respiring organisms). Additionally, murky water allows less light to penetrate it (diminishing algal and other plant productivity), it traps heat and allows the waters to become much warmer than clear ones (affecting species makeup and the amount of biologically-important dissolved gasses it can hold), and affects the chemical composition of the waters (through adsorption and particle dissolution reactions). Rain forests contribute to biologically-important gasses in the Earth's atmosphere: they produce a large percentage of the available O2 on the planet via photosynthesis (although the main source of oxygen on Earth is from phytoplankton in the oceans). When the forests are destroyed, the rate at which CO2 can be drawn from the atmosphere is diminished. CO2 is a "greenhouse" gas that helps regulate the temperature of our atmosphere. This gas is a biproduct of all respiring organisms, as well as a biproduct of the combustion of organic matter, such as fossil fuels. If CO2 builds up in the atmosphere, the average temperature on the surface of the Earth can increase, affecting most aspects of human life. As rain forest is cleared, what grows in its place is typically opportunistic species such as grasses. These are not sufficient to keep the area from eroding or to allow the regeneration of a biologically- diverse ecosystem in the area. Because barren rock or soil reflects a great deal more incident sunlight than does a forested area, the local "heat" budget for a region can be drastically changed by deforestation, thus affecting the local climate. Also, rain forests, particularly tropical ones, support a much greater number of species per unit area than other biomes on Earth. This species diversity is required for a healthy ecosystem. When we remove a large enough number of species from the species "web" of a complex ecosystem such as this, it can no longer fend off natural disasters such as disease or drought. Thus, even removing only part of a rain forest can cause the remaining forest to be non-sustainable or dramatically altered. Additionally, many plants are known to produce chemicals ("natural products") with enormous potential for a large range of uses (controlling diseases, manufacturing, etc..). Because there is a large species diversity in tropical rain forests and because many are remote and largely uncharted, it stands to reason that as new species go extinct each day, we are loosing important chemical producing organisms we haven't even discovered yet. Often times, even after a plant has been found to produce a chemical that is useful to humans, we must continue to rely on the plant to produce it for our use because artificial systhesis of the same material is expensive or otherwise impractical. A final reason to preserve rain forests is ascethic: These are truly beautiful regions of the planet, exploding with colors and aromas and exotic sounds. 14