托福tpo52听力lecture2 Interactions within an Ecosystem

托福tpo52听力lecture2 Interactions within an Ecosystem，那么接下来就跟着中国教育在线的小编详细了解一下吧。

Interactions within an Ecosystem托福听力原文翻译及问题答案

一、Interactions within an Ecosystem托福听力原文：

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托福听力中文翻译：

旁白：听一节环境科学课上的讲座。

女教授：今天我们将开始讨论生态系统。我想从阅读中强调的一点是，生态系统中有许多相互作用……动物之间的相互作用，生物和非生物之间的相互影响，等等。现在这些相互作用可以相当简单和直接。

啊，亚利桑那州的沙漠生态系统中有某些蚂蚁和啮齿动物物种，它们竞争相同的植物种子……竞争不仅影响蚂蚁和啮齿类种群的大小，还影响最终植物的数量。现在这种交互很容易看到，对吗；然而，生态系统中还有许多其他的相互作用，它们并不那么明显，需要更仔细的研究；你读到的例子是北美洲太平洋沿岸的森林生态系统…嗯…特别是鲑鱼的作用。

好的。正如你可能知道的，鲑鱼出生于淡水溪流中，它们迁移到海洋中度过大部分生命，然后回到它们出生的溪流中繁殖……或产卵。为了产卵，鲑鱼需要清凉的溪流来确保卵的存活……而周围森林中的树木在这里发挥着重要作用。它们的叶子为阳光提供遮荫。当伐木砍伐树木时，溪流向阳光开放，水变得更温暖。当水变暖时，水中溶解氧的浓度会降低……这会降低鲑鱼卵存活的几率。

树木也有助于保持河岸土壤的位置。鲑鱼不能在被沉积物污垢堵塞的河床产卵——来自周围地区……它们需要一条干净的砾石河床。布拉德？男学生：我读到鲑鱼也有助于保持溪流健康。女教授：对。鲑鱼提供碳和磷等重要营养物质，这些营养物质促进了溪流环境的多样性。好吧。嗯，鲑鱼需要树木才能成功繁殖。但令人惊讶的是，树木也需要鲑鱼…

熊市起着重要的中介作用。因此，在秋天，熊在准备冬眠时，正忙于增加体重。在鲑鱼产卵的45天里，每只熊大约捕获700条鱼。

熊在溪流中捕捉鲑鱼，然后把它们带回森林里吃……有时离溪流800米远。由于熊捕获的每条鱼只吃一半左右，其他动物如鹰、乌鸦和昆虫都会吃剩下的鱼。

玛丽亚？女学生：为什么熊把鲑鱼带到森林这么远？为什么不吃小溪边的鱼呢？

女教授：好吧，想象几只饥饿的熊在寻找鲑鱼。当一只熊捉到一条鱼时，另一只熊尝试偷鱼并不罕见。这些对抗可能相当激烈，所以把它带回森林更安全……到一个熊可以不受干扰地吃东西的地方。男学生：嗯，你说熊抓的每条鱼只吃一半？我的意思是，如果我是一只准备冬眠的熊，我可能会吃掉所有我能抓到的东西。

女教授：好吧，鲑鱼的某些部分更营养……比其他部分更油腻。事实上，熊只吃鱼的一部分，然后试着再钓一条，而不是吃整条鱼，这样更有效。好吧。所以，在食腐动物吃了剩下的鱼之后，只剩下鱼的骨架了。现在鲑鱼含有氮，所以它们的分解体和骨骼为周围的森林提供了大量氮。植物吸收这些氮，这是它们生长所需的，所以把这些氮转移到森林中是溪流附近的重要森林，鲑鱼实际上比其他森林成熟得更快。好吧。那么，为什么这一切都重要呢？嗯，鲑鱼有麻烦了。它们的一些种群已经灭绝，剩余的大多数种群由于过度捕捞和环境挑战而大大减少。现在，自然资源保护主义者可以尝试防止过度捕捞，但我的意思是，你可以看到这个生态系统内部的相互联系。我们已经谈到了树木对鲑鱼的重要性，以及伐木之类的东西可能产生的负面影响。所以你可以看到，保护这个生态系统需要付出广泛的努力。

三、Interactions within an Ecosystem托福听力问题：

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托福听力答案：

A1:正确答案：C

A2:正确答案：D

A3:正确答案：BD

A4:正确答案：C

A5:正确答案：C

A6:正确答案：B

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