原版英语RAZ 教案(Z) Prairies Alive!.pdf
www.readinga-Prairies Alive!Prairies Alive!A Reading AZ Level Z Leveled BookWord Count:1,966Visit www.readinga- for thousands of books and materials.Written by Alfred J.SmuskiewiczLEVELED BOOK ZWritten by Alfred J.SmuskiewiczPrairies Alive!Level Z Leveled Book Learning AZWritten by Alfred J.SmuskiewiczAll rights reserved.www.readinga-Photo Credits:Front cover,title page:Jim Brandenburg/Minden Pictures;back cover:Raymond Gehman/National Geographic Image Collection;page 3(top):James P.Blair/National Geographic Image Collection;page 3(bottom):Jupiter Images;page 4(top):Pierre Perrin/Sygma/Corbis;page 4(middle):Ted Wood/Aurora Photos;page 4(bottom):Eddi Boehnke/Corbis;page 7:Richard Hamilton Smith/Corbis;page 8(top):Ron Spomer/Visuals Unlimited;page 8(bottom):Danny Warren/iStock Photos;page 9:Heidi Natura/Conservation Research Institute/USDA-NRCS-Illinois;page 10(inset):Photo by Jeff Vanuga,USDA Natural Resources Conservation Service;page 10(main):Jim Richardson/National Geographic Stock;page 11:Samuel Strickler/D;page 12:National Biological Information Infrastructure;pages 13(main),19(both):Jim Brandenburg/Minden Pictures;page 13(left inset):John Cornell/Visuals Unlimited;page 13(right inset):Tim Fitzharris/Minden Pictures;page 14:Charlie Nye/The Indianapolis Star/AP Images;page 15,16(middle and bottom):Jim Pisarowicz/National Park Service;page 16(top):Lynn Betts,USDA Natural Resources Conservation Service;page 17(top):Ohio Department of Natural Resources,Division of Natural Areas&Preserves;page 17(bottom):David Cavagnaro/Visuals Unlimited;page 18(top):Barb Muenchau/National Park Service;page 18(bottom):Tui De Roy/Minden Pictures;page 20(top):Sumio Harada/Minden Pictures;page 20(bottom):Gary Kramer/NRCS/USDA;page 21(top):Michael Durham/Visuals Unlimited;page 21(middle left):Barry Mansell/npl/Minden Pictures;page 21(middle right):Chris Mattison;Frank Lane Picture Agency/Corbis;page 21(bottom left):Mary Ann McDonald/Visuals Unlimited;page 21(bottom right):Courtesy of Washington Department of Fish&Wildlife;page 4(footer),5(footer),6(footer),7(footer),8(footer),9(footer),10(footer),11(footer),12(footer),13(footer),14(footer),15(footer),16(footer),17(footer),18(footer),19(footer),20(footer),21(footer),22,23(footer):Jupiter Imageswww.readinga-Prairies Alive!CorrelationLEVEL ZUVN/A50Fountas&PinnellReading RecoveryDRA34What Are Grasslands?Have you ever been on a ship far out at seaor even in a boat in the middle of a large lake?In any direction you look,all you can see is water,right?Now imagine being in the middle of a sea of grass,surrounded by waves of green,golden,brown,and reddish grasses and multicolored flowers as far as the eye can see.This grassy sea is the home of hundreds of species of plants and animals.Different kinds of birds fly overhead,some swooping and diving for prey that live their lives mostly hidden among the grasses on the flat or gently rolling landscape.Grasslands in South America are called pampas.Grasslands in South Africa are called veld.Grasslands in Asia are called steppes.Table of ContentsWhat Are Grasslands?.4Three Types of North American Grasslands.6The Importance of Fire.10The Prairie Ecosystem.12Preserving the Prairies.14Plants of the Prairies .15Animals of the Prairies.18Glossary.23Index.24Prairies Alive!Level Z56This is what a large,natural grassland is likeits not like turf in peoples yards,which is mostly one color,2-inches tall,and hiding not much more than insects.Not all grasslands are alike,either.Different kinds of grasslands are found in North and South America,Europe and Asia,Africa,and Australiaevery continent on Earth except Antarctica.Grasslands usually grow in areas that get too much rain for deserts but not enough rain for forests.The main kinds of plants in grasslands are grasses,of course.Did you know that not all grasses are the same?Hundreds of different species populate the worlds grasslands.One thing that most grasses have in common is that they are tough,hardy plants that can survive fire,heat,freezing,drought,and grazing.Can you think of anything else that could survive all of that?Grasses have roots that grow deep underground to find and take in water and nutrients.New plants can grow from these roots when the stems and leaves above ground die,such as when they are burned by fire or eaten by animals.Three Types of North American GrasslandsNorth American grasslands are known as prairies.The amount of rainfall and type of soil makes each prairie different.There are three main typestallgrass,mixed-grass,and shortgrass prairies.Ill bet you can guess what the main difference is among the three.If you guessed the height of the grasses,you guessed right.Do You Know?The tallgrass prairie once covered over 140 million acres(56.7 million hectares)in North America.About 10 percent of this area remains.Historical area covered by each prairie typeGULF OF MEXICOCANADAUNITED STATESKEYshortgrass prairiesmixed-grass prairiestallgrass prairiesMEXICONPrairies Alive!Level Z78Tallgrass prairieLets start in the eastern part of North Americas prairie region and travel west,as many European settlers did in the 1800s.The tallgrass prairie comes first,and it includes much of Illinois,Iowa,Minnesota,North and South Dakota,Nebraska,Kansas,Oklahoma,and Texas.In the tallgrass prairie,it rains 30 to 40 inches (76102 cm)every year.In the tallgrass prairie,some grasses,such as big bluestem and Indian grass,grow taller than the average humanto heights of 8 feet(2.4 m)or more.The roots of these grasses can grow even moreto depths of 9 feet(2.7 m).In a tallgrass prairie,the soil is deeper,darker,and richer in nutrients than the soil in other kinds of prairies.Can you imagine traveling by foot through a tallgrass prairie?It would be easy to get lost.Mixed-grass prairieNow we move westward to the mixed-grass prairie,which is found in parts of North and South Dakota,Nebraska,Kansas,Oklahoma,and Texas.It gets between 15 and 25 inches(3864 cm)of rain per year.In the mixed-grass prairie,such grasses as little bluestem and sideoats grama grow to heights of between 2 and 3 feet(6191 cm).The soil in this kind of prairie is usually dark brown.Shortgrass prairieThe shortgrass prairie,which lies just east of the Rocky Mountains,gets only about 10 inches(25 cm)of rain every year.This prairie spreads into Pembina Trail Preserve,MinnesotaMixed-grass native prairie,South DakotaShortgrass prairie,MontanaPrairies Alive!Level Z910Montana,Wyoming,Colorado,New Mexico,and Texas.The shortgrass prairie gets little rain because the mountains create a“rain shadow”in this area.This means that warm,dry winds blowing down from the mountains make the area dry.In the shortgrass prairie,most grasses,such as buffalo grass and bunch grass,grow to between 8 and 18 inches(2046 cm)in height.The roots grow about 3 feet(91 cm)deep in the light brown soil.The Importance of FireMost things cannot survive firebut a prairie can!In fact,fire actually helps a prairie thrive.This is because prairie grasses have deep roots that new stems can easily grow from.During a fire,the flames may reach a temperature greater than 400 degrees Fahrenheit(204C),but the temperature below ground rises only a few degrees.So after the fire stops,the grass roots can quickly give rise to new stems.By contrast,if any young trees or shrubs are growing on the prairie,they will probably be killed by the flames.Were it not for fires,these trees and shrubs would continue to grow,and the prairie would turn into a forest.Managers of prairies set special fires,known as“controlled burns,”to help prevent trees and shrubs from growing.87654321123456 789101112131415Buffalo GrassWhite Wild IndigoPurple Prairie CloverJune GrassSide Oats GramaPrairie DropseedBig BluestemPale Purple ConeflowerSwitch GrassKentucky Blue GrassMissouri GoldenrodPorcupine GrassIndian GrassCylindrie Blazing StarLittle BluestemCompass PlantfeetPrairie PlantsPrairies Alive!Level Z1112Until the 1800s,fires occurred on the prairies when lightning struck the ground.Native American people,such as the Sioux,Pawnee,and Cheyenne,also set fire to the prairies.They sometimes set fire around a herd of bison(buffalo)to force the animals to run past a particular spot.Hunters would kill the bison,which would be used for food,clothing,and shelter.Native Americans also burned the prairie because the burnt plant material added nutrients to the soil when it decomposed.When Americans of European ancestry moved into the prairie region in the 1800s,they usually put out any fires,thinking they were dangerous.Because of this,many parts of the prairie became forests.The Prairie EcosystemAll the interactions of plants,animals,and nonliving things,including fire,make up the prairie ecosystem.The prairie ecosystem has six main parts:1)the Sun,2)producers,3)primary consumers,4)secondary consumers,5)decomposers,and 6)nonliving substances.The Sun,with its light and heat,provides energy for everything else in the ecosystem.The Suns energy flows through everything.Producers are the grasses and other plants.They use energy from the Sunalong with water,carbon dioxide gas from the air,and nutrients from the soilto make their own food.Primary consumers in the prairie ecosystem are the animals that eat the plants,such as jackrabbits that eat grasses and clover.These animals,also called herbivores,get their nutrients and energy directly from plants.Secondary consumers are the meat-eating animals,called carnivores,that eat the plant-eating animals.An example is a fox that eats jackrabbits.JackrabbitPrairie HerdsMillions of bison(buffalo)once lived in huge herds on the prairies.However,the new settlers did not want these animals living where they wanted to build farms and towns.So they killed them in great numbers.Bison were easy to kill because instead of running away,they stood in circles surrounding and protecting their young.By 1890,only about 500 bison remained.Then,some people began breeding the remaining bison in zoos and on ranches.Today,about 200,000 bison are living in protected areas,such as Yellowstone National Park.Prairies Alive!Level Z1314Decomposers in the prairie ecosystem are organisms that break down dead plants and animals into chemical substances in the soil.These organisms include bacteria and fungi,such as mushrooms.The chemical substances form nutrients that plants use to grow.These chemical substances and water are the nonliving parts of the prairie ecosystem.Preserving the PrairiesIn North America,few areas of natural prairie remain.Most prairies were changed into farms or cities long ago.However,some places still exist where you can get an idea of what it was like when the early settlers first saw the sea of grass.At these prairie preserves,scientists and volunteerspeople like youwork together to restore prairies to their natural condition.To learn whether any prairies are near you,check with your state department of natural resources.Ask whether there are any tasks for which you can volunteer to help,such as collecting seeds or counting birds.These activities are wonderful ways to learn about the great grasslands of North America.Do You Know?In the area where prairies are today,there was a warm,shallow ocean between about 440 million and 410 million years ago.Scientists know this from finding fossils and other signs of ancient sea animals in the region.Prairie PotholesAreas in prairies where water is present for part or all of the year are called prairie wetlands.Wetlands that have water for only part of the year are known as prairie potholes.These areas are important resting and breeding places for ducks and other birds that migrate(travel long distances during spring and fall).Prairie potholes also take in rainwater like a sponge,helping to prevent flooding.These cord grass seeds were collected to help restore the prairie.Prairies Alive!Level Z1516Plants of the PrairiesFollowing are a few examples of plants that can be found on prairies.GrassesBig BluestemBig bluestem is one of the tallest grasses on the tallgrass prairie,growing to a height of 8 feet(2.4 m)or more.It is blue only when the young shoots first come up in early summer.Later,the plant turns shades of red or brown.Big bluestems flowers grow in long hairy spikelettes(clusters)that look like the three front toes of a birds foot.That is why big bluestem is also known as“turkeyfoot”and“beardgrass.”Little BluestemLittle bluestem usually grows in drier areas than its big“brother,”big bluestem.It can reach a height of about 4 feet(1.2 m).Its flowers grow in short hairy spikelettes arranged in zigzag patterns at the top of its stems.Sideoats GramaThe flowers of sideoats grama hang off to one side of thin flower stalks.The plant usually grows to a height of 32 inches (81 cm)in mixed-grass or shortgrass prairies.This and other types of grama grass were important forage plants for the bison that once roamed in large herds across the prairies.Buffalo GrassBuffalo grass is another grass that was an important forage plant for bison.This plant grows about 6 inches(15 cm)high.In the 1800s,settlers used slabs of sod formed by buffalo grass like bricks to make their houses.Seed heads for little bluestem look fluffy.Buffalo grass would make a great central Texas lawn.Flowers on sideoats grama give the prairie some reddish color.Prairies Alive!Level Z1718Other PlantsCompositesMany prairie plants belong to the composite(sunflower)family.These plants have large“flowers”that are each made of many tiny flowers.The tiny flowers in the center,called disk flowers,are surrounded by a ring of other flowers,called ray flowers.Blazing stars are composites with bright pink,red,or purple flowers that look like colorful shooting stars.The compass plant is a composite with large leaves,the edges of which always point in a north-south direction.Goldenrods have bright yellow clusters of flowers in late summer and fall.LegumesMany prairie plants belong to the legume(pea)family.These plants all have flowers with complicated shapes.Prairie legumes(leh-GYOOMZ)include various kinds of clovers with white,yellow,red,or purple flowers.They also include wild indigos,which can have white or cream-colored flowers.The stems of wild indigos contain a blue dye that was used by early settlers to color clothing.Animals of the PrairiesA wide variety of animals live on prairies.Here are a few examples.GrouseGrouse are brown,chickenlike birds that live on the ground of prairies.They eat seeds,leaves,grains,berries,buds,and flowers.When a male grouse wants to attract a female,he dances,makes cooing sounds,and blows up a purple sac on his neck like a balloon.Grouse live in flocks called coveys.SnakesOne of the largest prairie reptiles is the bullsnake,a brownish snake that can grow to a length of 8 feet(2.4 m).It slithers through the grass looking for rodents,birds,and eggs to eat.It also hisses loudly!Other prairie snakes include the prairie kingsnake,the massasauga(also called the timber rattlesnake),and th
