『新东方在线托福阅读』为托福考生准备了ETS托福TPO/Official 40 Passage 2阅读练习：Why does the author mention “a mature floodplain tropical forest in the Amazon River basin” in the passage?真题题目及答案解析，TPO/Official 40 Passage 2阅读原文范文音频翻译

托福TPO/Official 40 Passage 2阅读原文Why does the author mention “a mature floodplain tropical forest in the Amazon River basin” in the passage?题目答案及解析-新东方托福官方网校手机版

当我们观察生物多样性（生物多样性）在地球陆地表面的分布方式时，我们发现它并非均匀。

When we look at the way in which biodiversity (biological diversity) is distributed over the land surface of the planet, we find that it is far from even.

与高纬度的同类地区相比，热带地区总体上包含的物种要多得多。

The tropics contain many more species overall than an equivalent area at the higher latitudes.

这似乎适用于许多不同的动植物群体。

This seems to be true for many different groups of animals and plants.

为什么高纬度地区的多样性比热带地区低？

Why is it that higher latitudes have lower diversities than the tropics?

也许这仅仅是土地面积的问题。

Perhaps it is simply a matter of land area.

热带地区的陆地表面积比高纬度地区大——当我们检查常用的地球曲面投影时，这一事实并不总是明显的，因为这往往会夸大高纬度地区的陆地面积——一些生物地理学家认为多样性的差异反映了这种影响。

The tropics contain a larger surface area of land than higher latitudes—a fact that is not always evident when we examine commonly used projections of Earth’s curved surface, since this tends to exaggerate the areas of land in the higher latitudes—and some biogeographers regard the differences in diversity as a reflection of this effect.

但生物学家克劳斯·罗德对数据的分析并不支持这一解释。

But an analysis of the data by biologist Klaus Rohde does not support this explanation.

虽然面积可能有助于生物多样性，但这肯定不是全部因素；否则，大片陆地的物种往往将更丰富。

Although area may contribute to biodiversity, it is certainly not the whole story; otherwise, large landmasses would always be richer in species.

生产力似乎也参与其中，尽管它的影响可能是间接的。

Productivity seems to be involved instead, though perhaps its influence is indirect.

在最适合植物生长的地方，也就是温度相对较高和均匀的地方，供水充足的地方，通常会发现大量的植被。

Where conditions are most suitable for plant growth—that is, where temperatures are relatively high and uniform and where there is an ample supply of water—one usually finds large masses of vegetation.

这导致了植物材料层中的复杂结构。

This leads to a complex structure in the layers of plant material.

例如，在热带雨林中，大量的植物在地面上堆积。

In a tropical rain forest, for example, a very large quantity of plant material builds up above the surface of the ground.

也有大量的物质，在地下形成根组织，但不太明显。

There is also a large mass of material, developed below ground as root tissues, but this is less apparent.

对地上物质的仔细分析表明，它被排列成一系列的层，确切的层数随着年龄和森林的性质而变化。

Careful analysis of the above-ground material reveals that it is arranged in a series of layers, the precise number of layers varying with age and the nature of the forest.

将植被的生物量（“生物量”）按层状排列的形式称为“结构”（与“组成”相对，后者指的是构成群落的有机体的种类）。

The arrangement of the biological mass (“biomass”) of the vegetation into layered forms is termed its “structure” (as opposed to its “composition,” which refers to the species of organisms forming the community).

结构本质上是植被的结构，就像一些热带森林的情况一样，它可能非常复杂。

Structure is essentially the architecture of vegetation, and as in the case of some tropical forests, it can be extremely complicated.

在亚马逊河流域的一片成熟的洪泛区热带森林中，树冠（森林的最上层，由树冠形成）呈现出分层结构。

In a mature floodplain tropical forest in the Amazon River basin, the canopy (the uppermost layers of a forest, formed by the crowns of trees) takes on a stratified structure.

树叶覆盖层在离地面约３、６和３０米的高度处有三个清晰的峰；最高的一层（位于５０米处）对应于很高的树木，这些树木没有主树冠，而是形成了自己的开放层。

There are three clear peaks in leaf cover at heights of approximately 3, 6, and 30 meters above the ground; and the very highest layer, at 50 meters, corresponds to the very tall trees that stand free of the main canopy and form an open layer of their own.

因此，这样的森林基本上包含四层树冠。

So, such a forest contains essentially four layers of canopy.

温带地区的森林通常只有两层树冠，因此它们的结构要简单得多。

Forests in temperate lands often have just two canopy layers, so they have much less complex architecture.

结构对栖息在某一地点的动物生活有很大的影响。

Structure has a strong influence on the animal life inhabiting a site.

它形成了动物进食、活动、栖息、生活和繁殖的空间环境。

It forms the spatial environment within which an animal feeds, moves around, shelters, lives, and breeds.

它甚至通过影响光照强度、湿度以及温度的范围和极值，在非常局部的水平上影响气候（“微气候”）。

It even affects the climate on a very local level (the “microclimate”) by influencing light intensity, humidity, and both the range and extremes of temperature.

例如，一个结构非常简单的草原植被区域，其地面微气候与上层树冠的微气候截然不同。

An area of grassland vegetation with very simple structure, for example, has a very different microclimate at the ground level from that experienced in the upper canopy.

那里风速较低，白天温度较低（但晚上较暖），地面附近的相对湿度要大得多。

Wind speeds are lower, temperatures are lower during the day (but warmer at night), and the relative humidity is much greater near the ground.

微气候的复杂性与植被结构的复杂性密切相关，一般来说，植被结构越复杂，在那里生存的动物种类就越多。

The complexity of the microclimate is closely related to the complexity of structure in vegetation, and generally speaking, the more complex the structure of vegetation, the more species of animal are able to make a living there.

热带的高植物生物量导致了环境中更大的空间复杂性，这使得可以占据一个地区的生物具有更高的多样性潜力。

The high plant biomass of the tropics leads to a greater spatial complexity in the environment, and this leads to a higher potential for diversity in the living things that can occupy a region.

高纬度的气候一般不利于生物量的大量积累，因此植被结构较简单，动物多样性也较低。

The climates of the higher latitudes are generally less favorable for the accumulation of large quantities of biomass; hence, the structure of vegetation is simpler and the animal diversity is consequently lower.

The word “distributed” in the passage is closest in meaning to

Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.

Which of the following is NOT mentioned in paragraph 3 as a condition that benefits plant growth?

The word “precise” in the passage is closest in meaning to

According to paragraph 3, which of the following statements best describes the difference between structure and composition?

Why does the author mention “a mature floodplain tropical forest in the Amazon River basin” in the passage?

What can be inferred from paragraph 4 about a region with a high level of diversity of animal species?

The word “consequently” in the passage is closest in meaning to

Look at the four squares  that indicate where the following sentence could be added to the passage. One example of such tropical abundance is found in Panama, which has 667 species of breeding birds—three times the number found in Alaska.  Where would the sentence best fit? Click on a square  to add the sentence to the passage.

Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points.

Latitude and Biodiversity When we look at the way in which biodiversity (biological diversity) is distributed over the land surface of the planet, we find that it is far from even. The tropics contain many more species overall than an equivalent area at the higher latitudes. This seems to be true for many different groups of animals and plants.  Why is it that higher latitudes have lower diversities than the tropics?  Perhaps it is simply a matter of land area.  The tropics contain a larger surface area of land than higher latitudes—a fact that is not always evident when we examine commonly used projections of Earth’s curved surface, since this tends to exaggerate the areas of land in the higher latitudes—and some biogeographers regard the differences in diversity as a reflection of this effect.  But an analysis of the data by biologist Klaus Rohde does not support this explanation. Although area may contribute to biodiversity, it is certainly not the whole story; otherwise, large landmasses would always be richer in species. Productivity seems to be involved instead, though perhaps its influence is indirect. Where conditions are most suitable for plant growth—that is, where temperatures are relatively high and uniform and where there is an ample supply of water—one usually finds large masses of vegetation. This leads to a complex structure in the layers of plant material. In a tropical rain forest, for example, a very large quantity of plant material builds up above the surface of the ground. There is also a large mass of material, developed below ground as root tissues, but this is less apparent. Careful analysis of the aboveground material reveals that it is arranged in a series of layers, the precise number of layers varying with age and the nature of the forest. The arrangement of the biological mass (“biomass”) of the vegetation into layered forms is termed its “structure” (as opposed to its “composition,” which refers to the species of organisms forming the community). Structure is essentially the architecture of vegetation, and as in the case of some tropical forests, it can be extremely complicated. In a mature floodplain tropical forest in the Amazon River basin, the canopy (the uppermost layers of a forest, formed by the crowns of trees) takes on a stratified structure. There are three clear peaks in leaf cover at heights of approximately 3, 6, and 30 meters above the ground; and the very highest layer, at 50 meters, corresponds to the very tall trees that stand free of the main canopy and form an open layer of their own. So, such a forest contains essentially four layers of canopy. Forests in temperate lands often have just two canopy layers, so they have much less complex architecture. Structure has a strong influence on the animal life inhabiting a site. It forms the spatial environment within which an animal feeds, moves around, shelters, lives, and breeds. It even affects the climate on a very local level (the “microclimate”) by influencing light intensity, humidity, and both the range and extremes of temperature. An area of grassland vegetation with very simple structure, for example, has a very different microclimate at the ground level from that experienced in the upper canopy. Wind speeds are lower, temperatures are lower during the day (but warmer at night), and the relative humidity is much greater near the ground. The complexity of the microclimate is closely related to the complexity of structure in vegetation, and generally speaking, the more complex the structure of vegetation, the more species of animal are able to make a living there. The high plant biomass of the tropics leads to a greater spatial complexity in the environment, and this leads to a higher potential for diversity in the living things that can occupy a region. The climates of the higher latitudes are generally less favorable for the accumulation of large quantities of biomass; hence, the structure of vegetation is simpler and the animal diversity is consequently lower.