托福tpo52聽力lecture2 Interactions within an Ecosystem

托福tpo52聽力lecture2 Interactions within an Ecosystem，那么接下來就跟著中國教育在線的小編詳細了解一下吧。

Interactions within an Ecosystem托福聽力原文翻譯及問題答案

一、Interactions within an Ecosystem托福聽力原文：

NARRATOR:Listen to part of a lecture in an environmental science class.

FEMALE PROFESSOR:Today we're going to begin discussing ecosystems.One important point I wanna emphasize from the reading is that there’re many interactions that take place within an ecosystem…interactions between animals,interactions between living and nonliving things,and so on.Now these interactions can be fairly simple and straightforward.

Ah,there are certain species of ants and rodents sharing a desert ecosystem in Arizona,and they compete for the same plant seeds…and the competition influences not only the size of the ant and rodent populations,but also the number of eventual plants.Now this interaction is easy to see,right? However,there're many other interactions within ecosystems that are not so apparent and require closer examination. And the example from your reading was the forest ecosystem along the Pacific coast of North America…um…specifically the role of salmon.

OK.As you probably know,salmon are born in freshwater streams,they migrate to oceans where they spend most of their lives,and then they return to the same streams where they were born to reproduce…or spawn.In order to spawn,salmon need cold,clear streams to ensure the survival of their eggs…and trees in the surrounding forest play an important role here.Their leaves provide shade from the sun.When logging removes the trees,the streams are open to the sun and the water becomes warmer.When the water warms up,the concentration of dissolved oxygen in the water decreases…and this reduces the chance that the salmon eggs will survive.

And the trees also help keep the soil on the banks of the stream in place.Salmon cannot spawn in streambeds clogged with sediment—dirt—from the surrounding area…they need a clean gravel streambed.Brad?MALE STUDENT:I've read that salmon also help keep streams healthy.FEMALE PROFESSOR:Right.Salmon contribute important nutrients like carbon and phosphorous,and these nutrients promote diversity in the stream environment.OK.Um,so salmon need trees to successfully reproduce.But surprisingly,trees also need salmon…

and bears play an important intermediary role.So in the autumn,bears are busy putting on extra weight as they prepare to hibernate.Each bear catches an estimated 700 fish during the 45 days that the salmon are spawning.

The bears catch the salmon in the streams,and then they carry them back into the forest to eat…sometimes as much as 800 meters from the streams.And since the bears only eat about half of each fish they catch,other animals like eagles,crows,and insects feed on the leftovers.

Maria?FEMALE STUDENT:Why do the bears bring the salmon so far into the forest?Why not just eat the fish near the streams?

FEMALE PROFESSOR:Well,imagine several hungry bears looking for salmon.When one bear catches a fish,it's not uncommon for another bear to try stealing it.These confrontations can be pretty intense,so it's safer to bring it back into the forest…to a place where the bear can eat undisturbed.MALE STUDENT:Um,you said that the bears only eat half of each fish they catch?I mean if I were a bear preparing to hibernate I'd probably eat everything I could catch.

FEMALE PROFESSOR:Well,certain parts of salmon are more nourishing…fattier than others.It's actually more efficient for a bear to only eat some parts of the fish,and then try catching another one,instead of eating the whole fish.OK.So after the scavengers have eaten the leftovers,only the fish's skeleton remains.Now salmon contain nitrogen,so their decomposing bodies and skeletons provide a lot of nitrogen to the surrounding forest.Plants absorb this nitrogen,which they need to grow,so the transfer of this nitrogen to the forests is important—forests near streams with salmon actually reach maturity faster than other forests.OK.So,why's all this important?Well,salmon are in trouble.Some of their populations have gone extinct,and most of the remaining populations have been significantly reduced by overfishing and environmental challenges.Now conservationists can try to prevent overfishing,but,well,I mean you can see the interconnections within this ecosystem.We already talked about the importance of trees to salmon,and the negative effect that something like logging can have.So you can see that protecting this ecosystem is going to take a broad effort.

二、Interactions within an Ecosystem托福聽力中文翻譯：

旁白：聽一節(jié)環(huán)境科學(xué)課上的講座。

女教授：今天我們將開始討論生態(tài)系統(tǒng)。我想從閱讀中強調(diào)的一點是，生態(tài)系統(tǒng)中有許多相互作用……動物之間的相互作用，生物和非生物之間的相互影響，等等?，F(xiàn)在這些相互作用可以相當(dāng)簡單和直接。

啊，亞利桑那州的沙漠生態(tài)系統(tǒng)中有某些螞蟻和嚙齒動物物種，它們競爭相同的植物種子……競爭不僅影響螞蟻和嚙齒類種群的大小，還影響最終植物的數(shù)量?，F(xiàn)在這種交互很容易看到，對嗎；然而，生態(tài)系統(tǒng)中還有許多其他的相互作用，它們并不那么明顯，需要更仔細的研究；你讀到的例子是北美洲太平洋沿岸的森林生態(tài)系統(tǒng)…嗯…特別是鮭魚的作用。

好的。正如你可能知道的，鮭魚出生于淡水溪流中，它們遷移到海洋中度過大部分生命，然后回到它們出生的溪流中繁殖……或產(chǎn)卵。為了產(chǎn)卵，鮭魚需要清涼的溪流來確保卵的存活……而周圍森林中的樹木在這里發(fā)揮著重要作用。它們的葉子為陽光提供遮蔭。當(dāng)伐木砍伐樹木時，溪流向陽光開放，水變得更溫暖。當(dāng)水變暖時，水中溶解氧的濃度會降低……這會降低鮭魚卵存活的幾率。

樹木也有助于保持河岸土壤的位置。鮭魚不能在被沉積物污垢堵塞的河床產(chǎn)卵——來自周圍地區(qū)……它們需要一條干凈的礫石河床。布拉德？男學(xué)生：我讀到鮭魚也有助于保持溪流健康。女教授：對。鮭魚提供碳和磷等重要營養(yǎng)物質(zhì)，這些營養(yǎng)物質(zhì)促進了溪流環(huán)境的多樣性。好吧。嗯，鮭魚需要樹木才能成功繁殖。但令人驚訝的是，樹木也需要鮭魚…

熊市起著重要的中介作用。因此，在秋天，熊在準(zhǔn)備冬眠時，正忙于增加體重。在鮭魚產(chǎn)卵的45天里，每只熊大約捕獲700條魚。

熊在溪流中捕捉鮭魚，然后把它們帶回森林里吃……有時離溪流800米遠。由于熊捕獲的每條魚只吃一半左右，其他動物如鷹、烏鴉和昆蟲都會吃剩下的魚。

瑪麗亞？女學(xué)生：為什么熊把鮭魚帶到森林這么遠？為什么不吃小溪邊的魚呢？

女教授：好吧，想象幾只饑餓的熊在尋找鮭魚。當(dāng)一只熊捉到一條魚時，另一只熊嘗試偷魚并不罕見。這些對抗可能相當(dāng)激烈，所以把它帶回森林更安全……到一個熊可以不受干擾地吃東西的地方。男學(xué)生：嗯，你說熊抓的每條魚只吃一半？我的意思是，如果我是一只準(zhǔn)備冬眠的熊，我可能會吃掉所有我能抓到的東西。

女教授：好吧，鮭魚的某些部分更營養(yǎng)……比其他部分更油膩。事實上，熊只吃魚的一部分，然后試著再釣一條，而不是吃整條魚，這樣更有效。好吧。所以，在食腐動物吃了剩下的魚之后，只剩下魚的骨架了?，F(xiàn)在鮭魚含有氮，所以它們的分解體和骨骼為周圍的森林提供了大量氮。植物吸收這些氮，這是它們生長所需的，所以把這些氮轉(zhuǎn)移到森林中是溪流附近的重要森林，鮭魚實際上比其他森林成熟得更快。好吧。那么，為什么這一切都重要呢？嗯，鮭魚有麻煩了。它們的一些種群已經(jīng)滅絕，剩余的大多數(shù)種群由于過度捕撈和環(huán)境挑戰(zhàn)而大大減少?，F(xiàn)在，自然資源保護主義者可以嘗試防止過度捕撈，但我的意思是，你可以看到這個生態(tài)系統(tǒng)內(nèi)部的相互聯(lián)系。我們已經(jīng)談到了樹木對鮭魚的重要性，以及伐木之類的東西可能產(chǎn)生的負面影響。所以你可以看到，保護這個生態(tài)系統(tǒng)需要付出廣泛的努力。

三、Interactions within an Ecosystem托福聽力問題：

Q1：1.What is the lecture mainly about?

A.A new approach to ensuring the survival of a forest ecosystem

B.Similarities between desert and forest-stream ecosystems

C.Interactions that take place within a North American forest ecosystem

D.Factors that have contributed to the preservation of salmon populations in forest ecosystems

Q2:2.Why does the professor mention ants and rodents competing for food?

A.To make sure the students understand the different components of an ecosystem

B.To point out the limited resources available to organisms in a desert ecosystem

C.To illustrate how different species adapt to extreme temperatures

D.To provide an example of an easily understood interaction within an ecosystem

Q3:3.According to the professor,how do trees contribute to the successful spawning of salmon?[Click on 2 answers]

A.They provide streams with nutrients that the salmon need.

B.They provide shade that keeps streams sufficiently cool.

C.They help salmon avoid predators by providing camouflage.

D.They reduce the amount of sediment entering streambeds.

Q4:4.What point does the professor make about bears carrying salmon away from streams?

A.It results in bears eating fewer fish.

B.It reduces the amount of food available to scavengers.

C.It improves the health of the surrounding trees.

D.It improves the water quality of the streams.

Q5:5.What does the professor imply about overfishing?

A.It is one of several reasons that the bear population has declined.

B.It is difficult to prevent in both oceans and streams.

C.It cannot be the sole focus for those working to prevent salmon depletion.

D.Its impact is minor compared to the problems caused by logging.

6.Why does one of the students say this:

A.To provide support for a hypothesis mentioned by the professor

B.To suggest that a bear behavior mentioned by the professor seems improbable

C.To explain why confrontations take place between bears

D.To explain why bears eat so much in a short time span

四、Interactions within an Ecosystem托福聽力答案：

A1:正確答案：C

A2:正確答案：D

A3:正確答案：BD

A4:正確答案：C

A5:正確答案：C

A6:正確答案：B

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