雅思(阅读)历年真题试卷汇编5及答案解析.doc
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1、雅思(阅读)历年真题试卷汇编 5 及答案解析(总分:80.00,做题时间:90 分钟)You should spend about 20 minutes on Questions 1-13 which are based on Reading Passage 1 below.WONDER PLANTThe wonder plant with an uncertain future: more than a billion people rely on bamboo for either their shelter or income, while many endangered species
2、 depend on it for their survival. Despite its apparent abundance, a new report says that many species of bamboo may be under serious threat.Section AEvery year, during the rainy season, the mountain gorillas of Central Africa migrate to the foothills and lower slopes of the Virunga Mountains to graz
3、e on bamboo. For the 650 or so that remain in the wild, its a vital food source. Although they eat almost 150 types of plant, as well as various insects and other invertebrates, at this time of year bamboo accounts for up to 90 per cent of their diet. Without it, says Ian Redmond, chairman of the Ap
4、e Alliance, their chances of survival would be reduced significantly.Gorillas arent the only locals keen on bamboo. For the people who live close to the Virungas, its a valuable and versatile raw material used for building houses and making household items such as mats and baskets. But in the past 1
5、00 years or so, resources have come under increasing pressure as populations have exploded and large areas of bamboo forest have been cleared to make way for farms and commercial plantations.Section BSadly, this isnt an isolated story. All over the world, the ranges of many bamboo species appear to
6、be shrinking, endangering the people and animals that depend upon them. But despite bamboos importance, we know surprisingly little about it. A recent report published by the UN Environment Programme(UNEP)and the International Network for Bamboo and Rattan(INBAR)has revealed just how profound is our
7、 ignorance of global bamboo resources, particularly in relation to conservation.There are almost 1,600 recognised species of bamboo, but the report concentrated on the 1,200 or so woody varieties distinguished by the strong stems, or culms, that most people associate with this versatile plant. Of th
8、ese, only 38 priority species identified for their commercial value have been the subject of any real scientific research, and this has focussed mostly on matters relating to their viability as a commodity.This problem isnt confined to bamboo. Compared to the work carried out on animals, the science
9、 of assessing the conservation status of plants is still in its infancy. “People have only started looking hard at this during the past 10-15 years, and only now are they getting a handle on how to go about it systematically,“ says Dr. Valerie Kapos, one of the reports authors and a senior adviser i
10、n forest ecology and conservation to the UNEP.Section CBamboo is a type of grass. It comes in a wide variety of forms, ranging in height from 30 centimetres to more than 40 metres. It is also the worlds fastest-growing woody plant; some species can grow more than a metre in a day. Bamboos ecological
11、 role extends beyond providing food and habitat for animals. Bamboo tends to grow in stands made up of groups of individual plants that grow from root systems known as rhizomes. Its extensive rhizome systems, which lie in the top layers of the soil, are crucial in preventing soil erosion. And there
12、is growing evidence that bamboo plays an important part in determining forest structure and dynamics. “Bamboos pattern of mass flowering and mass death leaves behind large areas of dry biomass that attract wildfire,“ says Kapos. “When these burn, they create patches of open ground within the forest
13、far bigger than would be left by a fallen tree.“ Patchiness helps to preserve diversity because certain plant species do better during the early stages of regeneration when there are gaps in the canopy.Section DHowever, bamboos most immediate significance lies in its economic value. Modern processin
14、g techniques mean that it can be used in a variety of ways, for example, as flooring and laminates. One of the fastest growing bamboo products is paper -25 per cent of paper produced in India is made from bamboo fibre, and in Brazil, 100,000 hectares of bamboo are grown for its production.Of course,
15、 bamboos main function has always been in domestic applications, and as a locally traded commodity its worth about US$4.5billion annually. Because of its versatility, flexibility and strength(its tensile strength compares to that of some steel), it has traditionally been used in construction. Today,
16、 more than one billion people worldwide live in bamboo houses. Bamboo is often the only readily available raw material for people in many developing countries, says Chris Staple-ton, a research associate at the Royal Botanic Gardens. “Bamboo can be harvested from forest areas or grown quickly elsewh
17、ere, and then converted simply without expensive machinery or facilities,“ he says. “In this way, it contributes substantially to poverty alleviation and wealth creation.“Section EGiven bamboos value in economic and ecological terms, the picture painted by the UNEP report is all the more worrying. B
18、ut keen horticulturists will spot an apparent contradiction here. Those whove followed the recent vogue for cultivating exotic species in their gardens will point out that if it isnt kept in check, bamboo can cause real problems. “In a lot of places, the people who live with bamboo dont perceive it
19、as being endangered in any way,“ says Kapos. “In fact, a lot of bamboo species are actually very invasive if theyve been introduced.“ So why are so many species endangered?There are two separate issues here, says Ray Townsend, vice president of the British Bamboo Society and arboretum manager at the
20、 Royal Botanic Gardens. “Some plants are threatened because they cant survive in the habitat - they arent strong enough or there arent enough of them, perhaps. But bamboo can take care of itself - it is strong enough to survive if left alone. What is under threat is its habitat.“ It is the physical
21、disturbance that is the threat to bamboo, says Kapos. “When forest goes, it is converted into something else: there isnt anywhere for forest plants such as bamboo to grow if you create a cattle pasture.“Section FAround the world, bamboo species are routinely protected as part of forest ecosystems in
22、 national parks and reserves, but there is next to nothing that protects bamboo in the wild for its own sake. However, some small steps are being taken to address this situation. The UNEP-INBAR report will help conservationists to establish effective measures aimed at protecting valuable wild bamboo
23、 species.Townsend, too, sees the UNEP report as an important step forward in promoting the cause of bamboo conservation. “Until now, bamboo has been perceived as a second-class plant. When you talk about places such as the Amazon, everyone always thinks about the hardwoods. Of course these are signi
24、ficant, but there is a tendency to overlook the plants they are associated with, which are often bamboo species. In many ways, it is the most important plant known to man. I cant think of another plant that is used so much and is so commercially important in so many countries.“ He believes that the
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