首页
登录
职称英语
NORTH AMERICAN GRASSLANDS1 In North America, native grasslan
NORTH AMERICAN GRASSLANDS1 In North America, native grasslan
游客
2025-02-08
30
管理
问题
NORTH AMERICAN GRASSLANDS
1 In North America, native grasslands occur primarily in the Great Plains in the middle of the continent. The North American prairie biome is one of the most extensive grasslands in the world, extending from the edge of the Rocky Mountains in the west to the deciduous forest in the east, and from northern Mexico in the south to Canada in the north. Average annual rainfall ranges from about 40 cm (16 inches) in the west to 80 cm (31 inches) in the east. Average annual temperatures range between 10 degrees and 20 degrees Celsius (50 to 68 degrees Fahrenheit). In the moist regions of the North American grasslands, especially in the northern Great Plains, rainfall is distinctly seasonal, and temperatures can vary widely from very hot in summer to bitter cold in winter.
2 One hundred years ago, the Great Plains grasslands were one vast, unbroken prairie. Much of the prairie is now farmland, the most productive agricultural region in the world, dominated by monocultures of cereal grains. Wheat, barley, soybeans, corn, and sunflowers occupy the land that was once prairie. In areas given over to grazing lands for cattle and sheep, virtually all the major native grasses have been replaced by
alien
species.
3 An important feature of the northern Great Plains grasslands is the presence of millions of glacial depressions that are now small ponds known as prairie potholes. They were formed during the most recent Ice Age, when streams flowed in tunnels beneath glacially formed sandy ridges. When the Ice Age ended around 12,000 years ago, the retreating glaciers created about 25 million depressions across a 300,000-square-mile landscape—about 83 potholes per square mile. As the ice blocks melted, much of the water was left behind, forming wetlands ranging in size from a tenth of an acre to several acres. The wetlands were soon surrounded by fluttering waves of grasses: shortgrass, mixed grass, and tallgrass.
4
Today these small wetlands still cover the prairies, although much of the landscape— including both native grasses and potholes—has been transformed to cropland and grassland for grazing.
What does remain of the wetlands, however, still serves as an important breeding area for more than 300 bird species, including large numbers of migrating shorebirds and waterfowl. The potholes fill up with water during spring rains and usually dry out by late summer. Every spring, birds arrive in great numbers—northern pintails, mallards, coots, and pied-billed grebes—4 to 6 million strong, to mate in the seasonal wetlands that dot portions of Minnesota, Iowa, North and South Dakota, Montana, Alberta, Saskatchewan, and Manitoba. Prairie pothole country produces half of North America’s 35 to 40 million ducks and is renowned worldwide as a "
duck factory
."
5 Recently biologists have discovered that the prairie pothole region is potentially a vast carbon sink: a natural sponge that absorbs carbon dioxide emissions from cars, factories, and power plants. Carbon dioxide is the most common of all the pollutants acting as greenhouse gases that heat up the atmosphere. Fortunately, however, carbon dioxide is captured naturally and stored in trees, soil, and plants. Scientists have termed
this
"carbon sequestration." They have determined that prairie potholes hold an average of 2.5 tons of carbon per acre per year when not being farmed. This means that if the entire pothole region in the United States and Canada were to stop being farmed, the region would store about 400 million tons of carbon over 10 years—the equivalent of taking almost 4 million cars off the road. Thus, preserving the potholes could be a way to
offset
greenhouse gas emissions that are warming the planet.
Glossary:
biome: one of the world’s major natural communities, classified by predominant vegetation
monoculture: cultivation of large land areas with a single plant variety [br] All of the following statements are true of the northern Great Plains EXCEPT
选项
A、Summer temperatures are very hot, while winter temperatures are very cold
B、An unbroken prairie now extends from the western mountains to the eastern forest
C、The original vegetation consisted of shortgrass, mixed grass, and tallgrass
D、A large number of small wetlands are found throughout the region
答案
B
解析
The passage does not state that an unbroken prairie now extends from the western mountains to the eastern forest. All of the other answers are given: ...temperatures can vary widely from very hot in summer to bitter cold in winter, The wetlands were soon surrounded by fluttering waves of grasses: shortgrass, mixed grass, and tallgrass; An important feature of the northern Great Plains grasslands is the presence of millions of glacial depressions that are now small ponds known as prairie potholes.(1.2)
转载请注明原文地址:https://tihaiku.com/zcyy/3947993.html
相关试题推荐
【21】[br]Mikathinksthatnon-nativespeakerscanimprove______.[originaltext
【21】[br]Shesaysthatnon-nativespeakerstudentsneedtoanticipateand_____
【21】[br]However,shepointsoutthatnativespeakerstudentswillusuallystop
TheDinee,aNativeAmerican(people)ofthesouthwesternUnitedStates,were(o
TheseatofFrance’sNorthAmericanholdingsintheeighteenthcenturywasQuebe
In(theearly)nineteenthcentury,theCherokeenationofAmericanIndians(was
TheSpanish(claiming)titleto(allof)NorthAmericaandestablishedthe(olde
ThemigrationofAfricanAmericansfromtheruralSouthtothe(industrial)Nort
TheNorthAmericanReview,a(magazinewas)first(published)in1815,wasoneo
ThetuliptreeisnativetotheeasternUnitedStates,______thetallestandla
随机试题
SciencewriterTomStandagedrawsaptparallelsbetweenthetelegraphandth
Thedesireforachievementisoneoflife’sgreatmysteries.Socialscientis
人的最根本的特性是人的()A.自然属性 B.社会属性 C.自由的属性 D.
以下关于嵌入式软件开发的叙述中,正确的是()。A.宿主机与目标机之间只需要建立
新生儿出生时身体红而四肢青紫,心率90/min,呼吸慢而不规则,四肢略屈曲,插鼻
对原发性肝癌早期诊断最有价值的是?( )A.甲胎蛋白测定 B.癌胚抗原测定
C左边四个图形可以拼合成如下图形:
某日,甲市“万路通”快递公司的员工张某在快递仓库门口装卸一个快递包裹时,看到该包
集体控制该安排的组合指的是那些既能联合起来控制该安排,又使得参与方数量最少的一个
某县医院因收治多例人感染导致病性禽流感患者未按规定报告受到行政处罚。为此,该医院
最新回复
(
0
)