Howdeserts are formed
A
A desertrefers to a barren section of land, mainly in arid and semi-arid areas, wherethere is almost no precipitation, and the environment is hostile for anycreature to inhabit. Deserts have been classified in a number of ways,generally combining total precipitation, how many days the rainfall occurs,temperature, humidity, and sometimes additional factors. In some places,deserts have clear boundaries marked by rivers, mountains or other landforms,while in other places, there are no clear-cut borders between desert and otherlandscape features.
B
In aridareas where there is not any covering of vegetation protecting the land, sandand dust storms will frequently take place. This phenomenon often occurs alongthe desert margins instead of within the deserts, where there are already nofiner materials left. When a steady wind starts to blow, fine particles on theopen ground will begin vibrat-ing. As the wind picks up, some of the particlesare lifted into the air. When they fall onto the ground, they hit otherparticles which will then be jerked into the air in their turn, initiating achain reaction.
C
Therehas been a tremendous deal of publicity on how severe desertification can be,but the academic circle has never agreed on the causes of desertification. Acommon misunderstanding is that a shortage of precipitation causes thedesertification—even the land in some barren areas will soon recover after therain falls. In fact, more often than not, human activities are responsible fordesertification. It might be true that the explo-sion in world population,especially in developing countries, is the primary cause of soil degradationand desertification. Since the population has become denser, the cultiva-tionof crops has gone into progressively drier areas. It’s especially possible forthese regions to go through periods of severe drought, which explains why cropfailures are common. The raising of most crops requires the natural vegetationcover to be removed first; when crop failures occur, extensive tracts of landare devoid of a plant cover and thus susceptible to wind and water erosion. Allthrough the 1990s, dryland areas went through a population growth of 18.5 percent, mostly in severely impoverished develop-ing countries.
D
Livestockfarming in semi-arid areas accelerates the erosion of soil and becomes one ofthe reasons for advancing desertification. In such areas where the vegetationis domi-nated by grasses, the breeding of livestock is a major economicactivity. Grasses are necessary for anchoring barren topsoil in a dryland area.When a specific field is used to graze an excessive herd, it will experience aloss in vegetation coverage, and the soil will be trampled as well as bepulverised, leaving the topsoil exposed to destructive erosion elements such aswinds and unexpected thunderstorms. For centuries, nomads have grazed theirflocks and herds to any place where pasture can be found, and oases haveoffered chances for a more settled way of living. For some nomads, whereverthey move to, the desert follows.
E
Treesare of great importance when it comes to maintaining topsoil and slowing downthe wind speed. In many Asian countries, firewood is the chief fuel used forcooking and heating, which has caused uncontrolled clear-cutting of forests indryland ecosystems. When too many trees are cut down, windstorms and duststorms tend to occur.
F
What’sworse, even political conflicts and wars can also contribute todesertification. To escape from the invading enemies, the refugees will movealtogether into some of the most vulnerable ecosystems on the planet. Theybring along their cultivation traditions, which might not be the right kind ofpractice for their new settlement.
G
In the20th century, one of the states of America had a large section of farmland thathad turned into desert. Since then, actions have been enforced so that such aphenomenon of desertification will not happen again. To avoid the reoccurringof desertification, people shall find other livelihoods which do not rely ontraditional land uses, are not as demanding on local land and natural resource,but can still generate viable income. Such livelihoods include but are notlimited to dryland aquaculture for the raising of fish, crustaceans andindustrial compounds derived from microalgae, greenhouse agriculture, andactivities that are related to tourism. Another way to prevent the reoccurringof desertification is bringing about economic prospects in the city centres ofdrylands and places outside drylands. Changing the general economic andinstitutional structures that generate new chances for people to supportthemselves would alleviate the current pres-sures accompanying thedesertification processes.
H
Innowadays society, new technologies are serving as a method to resolve theproblems brought by desertification. Satellites have been utilised toinvestigate the influence that people and livestock have on our planet Earth.Nevertheless, it doesn’t mean that alterna-tive technologies are not needed tohelp with the problems and process of desertification.
Questions14 - 20
ReadingPassage 2 has eight paragraphs, A-H.
Whichparagraph contains the following information?
Writethe correct letter, A-H, in boxes 14-20 on your answer sheet.
NB Youmay use any letter more than once.
14.a referenceto the irregular movement of particles
15.mentionof a productive land turning into a desert in the 20th century
16.typesof deserts
17.mentionof technical methods used to tackle the problems of deserts
18.theinfluence of migration on desertification
19.lackof agreement among the scientists about the causes of desertification
20.adescription of the fatal effects of farming practice
Questions21 - 26
Do thefollowing statements agree with the information given in Reading Passage 2?
In boxes21-26 on your answer sheet, write
TRUE ifthe statement agrees with the information
FALSE ifthe statement contradicts the information
NOTGIVEN if there is no information on this
21.It isdifficult to ascertain where the deserts end in some areas.
22.Mediais uninterested in the problems of desertification.
23.Themost common cause of desertification is the lack of rainfall.
24.Farminganimals in semi-arid areas will increase soil erosion.
25.Peoplein Asian countries no longer use firewood as the chief fuel.
26.Technologystudying the relationship of people, livestock and desertification has not yetbeen invented.
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