探索亚马逊 雨林顶端.doc

1、Journey into Amazonia: The Big TopNGC 全民英檢:探索亞馬遜雨林頂端播出時間:11 月 5 日 星期六 11:00-12:00The rainforest of Amazonia-where life in all its beauty and myriad formsreigns supreme.Less known then the surface of Mars,its inhabitants stranger than science fiction.this is Earths final, unexplored frontier.This is

2、Amazonias “Big Top“!The worlds mightiest riverbreaks through the canopyof the largest tropical rainforeston the planet.Combined with its tributaries,the Amazon drains into an areaof almost seven million square kilometres-more than half of South America.Like a giant circus tentnine times the size of

3、Texas,Amazonias tree covered worldhosts the greatest variety of plantsand animals on the planet.Sixty meters above the ground,less studied than the sea floor.Until recently, this incredible spectacledefied even the most intrepid scientistsand explorers.So many of its riches have yet to be recordedth

4、at it is believed that this bizarreand beautiful canopy could househalf of all the worlds species.In addition to millions of insects,Amazonias impressive cast of charactersincludes at least 300 different mammals.At least one hundred seventy-fivedifferent lizards.Over four hundred reptiles and amphib

5、ians.Tree climbers of every shape and size, And a third of the worlds birds.These magnificent creaturesall have their own unique tricks and talents,costumes and camouflage,and command performances.A 100 years ago the American explorer,William Beebe, wrote of the Amazon:“Yet another continent of life

6、remains to be discovered,not upon the earth,but one or two hundred feet above it,extending over thousands of square miles.There awaits a rich harvestfor the naturalist who overcomes the obstacles-gravitation, ants, rotten trunks-and mounts to the summit of the jungle trees.“Since Beebe marvelledat t

7、his incredible spectacle,scientists have had to multiply-many times over- all previous estimatesof the extent of life in these treetops.Only recently, the sheer number of termiteshas come to light- More than 200 speciescall the Amazon river basin their home-a cumulative massthree times that of all t

8、he birdsand mammals in the rainforest.Yet almost a hundred years laterAmazonia is revealing her secrets slowlylike crumbs from a giants banquet table.For a vast number of species,the canopy of this tropical rainforestis a desirable place to live.With so many creatures clamouringfor a piece of the pi

9、e in this high-wire world,competition for survivalin this big top is fierce.Millions of years of neck-and-neck rivalrymean that these animalshave evolved their own unique strategiesfor survival in the rainforest canopy.Evolution has led the slothup a more leisurely ladderto its place in the canopy.W

10、ith only half the musclesof other animals its size,the sloth subsists on one of the poorest diets.This languid mammalcan take up to a monthto travel two kilometres.if it had to.Although it can stand,it cant walk on its feet,so it must drag itself around by its hands.In the water, however,this “lazy

11、beast“ becomes somethingof a “Bathing Beauty“ and can swim quite well.Avoiding any strenuous competition for food,the three-toed sloth selects the leavesand twigs only a few other animals can stomach.With this low-cal diet,the sloth has little energy to spare,so it sleeps up to nine-teen hours a day

12、.It locks itself under a hard-to-reach branchto digest-it will take a hundred hoursto process a single belly full.Its ability to rotate its headalmost full circle means this contortionistcan keep an eye out for predators.Its also the only wild animalto have plants living on it.Each hair has microsco

13、pic grooveswhich provide a comfortable homefor olive-green algae.Its believed that these plants-and its extended naps-help camouflage the slothfrom its chief predator, the Harpy eagle.Sloths give birth to a single baby-which spends six to nine monthsclinging to its mother.Three-toed sloths are not n

14、ormally aggressive,but like any mother defending her child,she has a trick or two up her sleeve.You are what you eat in the Rainforestand leaf-eaters fall low on the list.The largest monkeys in the New World,the howler monkeys are not finickywhen it comes to food, which may explainwhy they are also

15、the most common monkeyin Amazonia. It hasnt turnedto the low-calorie extremes of the sloth,but it eats poorer farethan just about any other monkey.Like the sloth, the Howlers slow metabolismforces them into the top-most branchesof the canopy where they can warm upin the morning sunshine and jumpstar

16、t their day.They rarely explore much of the forestand when they do, they cover less distancethan other monkeys in the Amazonian Basin.Less energetic. Less fastidious.Less curious.Howlers do one thing more loudlythan just about any other land animal:Howl.In fact, these guttural soundscan travel up to

17、 five kilometresthrough the dense forest.It is said that when the first explorerspenetrated the depths of the rainforest,and heard the howlers calls,they fled in terror-fearing that some monster had encircled them.Oddly, these bellicose howls and hootsactually kept the peace by defining territoryand

18、 keeping the monkey troopsout of conflict.Standing one meter high,weighing in at eight kilos,with a two meter wingspan,the Harpy Eagle is unequalled in strength.According to Greek mythology,the Harpies were half-woman,half-bird monsters which swooped downfrom the heavens to seize the soulsof the dea

19、d and punish them.Today its a tamarin that facesthe most powerful talons of any bird on earth.Unassailable, the Harpy Eagleheadlines Amazonias Big Top.Beneath the multi-layered worldof the canopy, the groundlingscompete for survival.But in the tropics,physical conflict is often a dangerousand deadly

20、 last resort.Millions of disease-promoting organismswill invade even the most minor injury,causing fatal infections.Avoiding conflict is a constant pre-occupationin nature, especially here.To avoid surprise encounters,the animals repeatedly announce their presence.While howlers use soundto signal to

21、 other groups-the tiny squirrel monkey has evolveda less raucous though no less discreet method.It urinates on its hands and feetto leave its personal signature-a chemical barcode-as it scampers along the branches.But no system is foolproof,and where animals compete for resources,disputes over real

22、estate are inevitable.Although its heavier than the squirrel monkey,the capuchins tail cant grip as strongly.Its completely outmatched.Despite putting up a good fight,it flees the canopyand escapes to the forest floor.Sometimes the reason for these boutsis unclear- especially when the participantsar

23、ent obvious competitors-such as parrots and monkeys.According to Indian mythology,the golden-handed tamaringot its conspicuous markingsfrom having to roll out the sun each morning.Tamarins are naturally inquisitive.They like to know what the neighboursare up to.This golden-handed tamarin, however,ta

24、kes its curiosity to dangerous lengths.Teasing the neighbouring macaws.But the macaws are not amused.Their powerful claws and nut-cracker beaksmake this a risky game of cat and mousefor the tamarin.Out-numbered, the tamarindecides it is time to quitwhile its still ahead.The tamarin is only a minor d

25、istraction.The macaws have other, more important mattersto attend to- The breeding seasonis approaching, so the two birds“get in the mood“ by preening each othersfeathers and faces.They will mate and pair for life. The macaws are some of the forestsmost extravagantly conspicuous inhabitants.But for

26、each known rainforest species,there are many more unknown species.Yet all these creature play a rolein the jungles intricate dramaof interdependence.In the give and take tradings of Amazoniathe most intricate relationshipsin the rainforest are between animals and trees.In this competitive market,lea

27、ves are the commonest currency.Some trees produce toxinsto repel insect invaders,but at a cost that drains the treeof valuable energy.Other trees have developeda more diplomatic solution.Theyve struck up an armisticewith some of the ants.These trees provide one particular kind of antwith room and bo

28、ard.At the base of each leafs stem,special nectar spouts provide the antswith a steady supply of high-energy drinks.In return the tiny ant vigilantesact as neighbourhood watchand defend the tree from attack.They will even take on and drive awaythe far larger leaf-cutters.The arrangement suits both p

29、arties.“Scratch my back and Ill scratch yours“.or in this case “Feed me sweetsand Ill bite the legs of your enemy.“Such interdependence providesa strategic advantage in a deceptively lushenvironment, because its more difficultto survive than it looks.On the darkened forest floor,the lack of sunlight

30、 strangles many plants.At the other extreme, the top-most branchesrisk being seared by the sun.But somehow, despite everything.Life thrives.April, and the storm cloudsroll in again across the mantle of Amazonia.The dry season is over.The annual deluge sweeps across the whole faceof this epic wildern

31、ess.The waterworlds reassert their dominanceover the land, bringing new life.Aquatic prey and predators,like the giant otters, return to feast.The mighty Amazon and its tributariesescape their banks, taking holdof the land and submergingalmost 350,000 square kilometres,and area larger than Englandto

32、 a depth of over ten meters.Here, amidst the flooded forests,the most dramatic events in the lifeof the canopy will soon unfold.The surging water-levels encourage the treesto put on a dazzling displayof floral fireworks.The flooded forests make uponly a small fraction of Amazonia-only two percent- but almost halfof all the flowering trees and plantsin the entire rainforest grow and bloom here.The sudden explosion of colourattracts an equally phenomenalconcentration of life.Sixty meters up in the air,the stage is set for a spectacular flower show.