In the late nineteenth century, ecology began to grow into an independent science from its roots in natural history and plant geography. The emphasis of this new "community ecology" was on the composition and structure of communities consisting of different species. In the early twentieth century, the American ecologist Frederic Clements pointed out that a succession of plant communities would develop after a disturbance such as a volcanic eruption, heavy flood, or forest fire. An abandoned field, for instance, will be invaded successively by herbaceous plants (plants with little or no woody tissue), shrubs, and trees, eventually becoming a forest. Light-loving species are always among the first invaders, while shade-tolerant species appear later in the succession.
Clements and other early ecologists saw almost lawlike regularity in the order of succession, but that has not been substantiated. A general trend can be recognized, but the details are usually unpredictable. Succession is influenced by many factors: the nature of the soil, exposure to sun and wind, regularity of precipitation, chance colonizations, and many other random processes.
The final stage of a succession, called the climax by Clements and early ecologists, is likewise not predictable or of uniform composition. There is usually a good deal of turnover in species composition, even in a mature community. The nature of the climax is influenced by the same factors that influenced succession. Nevertheless, mature natural environments are usually in equilibrium. They change relatively little through time unless the environment itself changes.
For Clements, the climax was a "superorganism," an organic entity. Even some authors who accepted the climax concept rejected Clements' characterization of it as a superorganism, and it is indeed a misleading metaphor. An ant colony may be legitimately called a superorganism because its communication system is so highly organized that the colony always works as a whole and appropriately according to the circumstances. But there is no evidence for such an interacting communicative network in a climax plant formation. Many authors prefer the term "association" to the term "community" in order to stress the looseness of the interaction.
Even less fortunate was the extension of this type of thinking to include animals as well as plants. This resulted in the "biome," a combination of coexisting flora and fauna. Though it is true that many animals are strictly associated with certain plants, it is misleading to speak of a "spruce-moose biome," for example, because there is no internal cohesion to their association as in an organism. The spruce community is not substantially affected by either the presence or absence of moose. Indeed, there are vast areas of spruce forest without moose. The opposition to the Clementsian concept of plant ecology was initiated by Herbert Gleason, soon joined by various other ecologists. Their major point was that the distribution of a given species was controlled by the habitat requirements of that species and that therefore the vegetation types were a simple consequence of the ecologies of individual plant species.
With "climax," "biome," "superorganism," and various other technical terms for the association of animals and plants at a given locality being criticized, the term "ecosystem" was more and more widely adopted for the whole system of associated organisms together with the physical factors of their environment. Eventually, the energy-transforming role of such a system was emphasized. Ecosystems thus involve the circulation, transformation, and accumulation of energy and matter through the medium of living things and their activities. The ecologist is concerned primarily with the quantities of matter and energy that pass through a given ecosystem, and with the rates at which they do so.
Although the ecosystem concept was very popular in the 1950s and 1960s, it is no longer the dominant paradigm. Gleason's arguments against climax and biome are largely valid against ecosystems as well. Furthermore, the number of interactions is so great that they are difficult to analyze, even with the help of large computers. Finally, younger ecologists have found ecological problems involving behavior and life-history adaptations more attractive than measuring physical constants. Nevertheless, one still speaks of the ecosystem when referring to a local association of animals and plants, usually without paying much attention to the energy aspects.
Paragraph 2: Clements and other early ecologists saw almost lawlike regularity in the order of succession, but that has not been substantiated. A general trend can be recognized, but the details are usually unpredictable. Succession is influenced by many factors: the nature of the soil, exposure to sun and wind, regularity of precipitation, chance colonizations, and many other random processes.
1. According to paragraph 2, which of the following is a criticism of Clements’ view of succession?
O The principles of succession are more lawlike than Clements thought they are.
O More evidence is needed to establish Clements’ predictions about succession.
O The details of succession are affected by random processes.
O Many of the factors that determine which plants will grow in an environment, such as the nature of the soil and the exposure to sun, do not change at all.
2.The word “substantiated” in the passage is closest in meaning to
O confirmed
O noticed
O defined
O publicized
3.The word “trend” in the passage is closest in meaning to
O probability
O picture
O lawlike regularity
O tendency
Paragraph 3: The final stage of a succession, called the climax by Clements and early ecologists, is likewise not predictable or of uniform composition. There is usually a good deal of turnover in species composition, even in a mature community. The nature of the climax is influenced by the same factors that influenced succession. Nevertheless, mature natural environments are usually in equilibrium. They change relatively little through time unless the environment itself changes.
4.The word “likewise” in the passage is closest in meaning to
O sometimes
O similarly
O apparently
O consequently
Paragraph 4: For Clements, the climax was a "superorganism," an organic entity. Even some authors who accepted the climax concept rejected Clements' characterization of it as a superorganism, and it is indeed a misleading metaphor. An ant colony may be legitimately called a superorganism because its communication system is so highly organized that the colony always works as a whole and appropriately according to the circumstances. But there is no evidence for such an interacting communicative network in a climax plant formation. Many authors prefer the term "association" to the term "community" in order to stress the looseness of the interaction.
5.The word “legitimately” in the passage is closest in meaning to
O commonly
O broadly
O properly
O officially
6.According to paragraph 4, why do many authors prefer the term “association” to “community” when describing a climax plant formation?
O Because the term “association” does not suggest the presence of a tight network involving interactive communication.
O Because the term “association” indicates that the grouping is not necessarily beneficial to all members.
O Because the term “community” indicates continuing dynamic development that a climax formation does not have.
O Because the term “community” suggests an organization that has been designed for a specific purpose.
Paragraph 5: Even less fortunate was the extension of this type of thinking to include animals as well as plants. This resulted in the "biome," a combination of coexisting flora and fauna. Though it is true that many animals are strictly associated with certain plants, it is misleading to speak of a "spruce-moose biome," for example, because there is no internal cohesion to their association as in an organism. The spruce community is not substantially affected by either the presence or absence of moose. Indeed, there are vast areas of spruce forest without moose. The opposition to the Clementsian concept of plant ecology was initiated by Herbert Gleason, soon joined by various other ecologists. Their major point was that the distribution of a given species was controlled by the habitat requirements of that species and that therefore the vegetation types were a simple consequence of the ecologies of individual plant species.
7.In paragraph 5, the author challenges the idea of a “biome” by noting that
O there are usually no very strong connections among the plants and animals living in a place
O plants and animals respond in the same way to the same circumstances
O particular combinations of flora and fauna do not generally come about purely by chance
O some animals are dependent on specific kinds of plants for food
8.Why does the author make the statement, “Indeed, there are vast areas of spruce forest without moose” ?
O To highlight a fact whose significance the ecologist Herbert Gleason had missed
O To propose the idea that a spruce forest is by itself a superorganism
O To emphasize that moose are not limited to a single kind of environment
O To criticize the idea of a spruce-moose biome
9.The word “initiated” in the passage is closest in meaning to
O approved
O identified
O started
O foreseen
10.According to paragraph 5, Gleason’s opposition to the Clementsian views of plant ecology was based on the claim that plant species grow in places where
O they can enter into mutually beneficial relationships with other species
O conditions suit them, regardless of whether particular other species are present
O habitats are available for a wide variety of plant and animal species
O their requirements are met, and those of most other species are not
Paragraph 6: With "climax," "biome," "superorganism," and various other technical terms for the association of animals and plants at a given locality being criticized, the term "ecosystem" was more and more widely adopted for the whole system of associated organisms together with the physical factors of their environment. Eventually, the energy-transforming role of such a system was emphasized. Ecosystems thus involve the circulation, transformation, and accumulation of energy and matter through the medium of living things and their activities. The ecologist is concerned primarily with the quantities of matter and energy that pass through a given ecosystem, and with the rates at which they do so.
11.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.
O Unlike the terms “climax”, “biome,” and “superorganism,” which refer to the particular association of plants and animals at a given location, the term “ecosystem” refers specifically to the physical factors within an environment.
O The terms “climax,” “biome,” “superorganism,” and “ecosystem” all refer to the system of plants and animals in an associated environment, but some are more controversial than others.
O When the older terms of ecology became too technical, they were replaced by the more popular and more widely used term “ecosystem.”
O The term “ecosystem” gradually replaced discredited terms for the combination of a physical environment and the plants and animals living together in it.
12.According to paragraph 6, what did ecologists mainly study when the ecosystem concept was the dominant paradigm?
O The physical factors present in different environments
O The typical activities of animals and the effect of those activities on plants
O The rates at which ecosystems changed from one kind to another
O The flow of energy and matter through ecosystems
Paragraph 7: Although the ecosystem concept was very popular in the 1950s and 1960s, it is no longer the dominant paradigm. ■ Gleason's arguments against climax and biome are largely valid against ecosystems as well. ■ Furthermore, the number of interactions is so great that they are difficult to analyze, even with the help of large computers. Finally, younger ecologists have found ecological problems involving behavior and life-history adaptations more attractive than measuring physical constants. ■ Nevertheless, one still speaks of the ecosystem when referring to a local association of animals and plants, usually without paying much attention to the energy aspects. ■
13.Look at the four squares [■] that indicate where the following sentence could be added to the passage.
They may be more interested in researching, for example, the adaptations that some aquatic animals undergo to survive in dry desert environments.
Where would the sentence best fit ?
14.Directions: An introductory sentence for a brief summary of the passage is provied 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.
The study of the combination of plant species that inhabit a particular locality became a scientific discipline toward the end of the nineteenth century.
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Answer Choices
O Areas that are recovering from serious disturbances like volcanic eruptions and heavy floods provide special opportunities to observe the development of plant communities.
O Whether a given species will be found in a given ecosystem strongly depends on what other species it would interact with in that ecosystem.
O Computer-aided studies of entire system of associated organisms together with their environment provide a solid basis for current studies of specific ecological problems.
O According to the earliest theories of ecology, the development of plant communities proceeds in lawlike fashion and results in stable climax communities.
O The idea of associations of plants and animals that function as “superorganisms” was later rejected by biologists who saw no strong evidence in support of that idea.
O The once popular idea of communities as integrated ecosystems has been largely rejected by modern ecologists, who are more interested in problems involving behavior and adaptations.
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在19世紀末期，生態(tài)學開始從它的源頭——自然歷史學和植物地理學中脫離出來成為一門獨立的學科。這種新的概念“群落生態(tài)”強調的是不同物種構成的群落中的組成和結構。在20世紀早期，美國生態(tài)學家弗雷德里克•克萊門茨指出植物群落會在一個大變動（比如火山爆發(fā)、泥石流或者森林大火）之后發(fā)生演變。比如一塊廢棄的土地，就會接連受到草類植物（那些沒有或只有很少木質結構的植物）、灌木和樹木的入侵，最終形成一片森林。喜陽植物總是第一批入侵者，而那些喜陰植物隨后出現。
克萊門茨和其他早期的生態(tài)學家從演變的順序中看到了類似定律的規(guī)律性，但這個規(guī)律性還沒有得到證實。我們可以看出大概的趨勢，但是細節(jié)通常無法預見。演變受很多因素影響：土壤狀況，曝光和曝風，降水規(guī)律，意外殖民和其他隨機過程。
演變的最后階段被克萊門茨和早期生態(tài)學家稱為頂級群落，它同樣不可預測，組成也不單一。通常會發(fā)生大量的物種組成的更替，即使是在成熟的群落也同樣如此。頂級群落本質上同樣受到那些影響演變的因素的影響。盡管如此，成熟的自然環(huán)境通常處于平衡狀態(tài)。它們隨時間改變相對較少，除非環(huán)境本身發(fā)生變化。
對于克萊門茨來講，頂級群落是一個“超級有機體”，一個有機的個體。即使那些接受頂級群落概念的作者也拒絕接受克萊門茨關于超級有機體的描述，它的確是一個誤導人的隱喻。一個蟻群被稱作超級有機體還比較合理，因為它的通信系統(tǒng)組織非常嚴密，在某些情形下這些群落能夠像一個整體一樣巧妙運作。但是沒有證據表明在頂級群落植物系統(tǒng)中有這樣一種相互影響的交流系統(tǒng)。相比“群落”，很多作者更喜歡用“聯(lián)系”用以強調交互的松散性。
更不幸的是這種思考方式從植物擴展到了動物。于是就產生了生物群落的概念——一種動物群落和植物群落共存的結合體。盡管很多動物確實和一些植物緊密聯(lián)系，但諸如“云杉麋鹿生態(tài)系統(tǒng)”的說法仍然具有誤導性，因為云杉和麋鹿之間并沒有像一個有機體那樣有內在聯(lián)系。云杉群落并沒有極大地受到麋鹿存在或者不存在的影響。實際上有很多云杉林并沒有麋鹿。對克萊門茨關于植物群落概念的反對意見最早是由赫伯特•格里森提出來的，并且獲得了很多其他生態(tài)學家的支持。他們的主要觀點是給定物種的分布是由棲息地物種需求決定的，因此植被類型是簡單的單個植物類型生態(tài)的結果。
盡管頂級群落，生態(tài)群落，超級有機體和許多對給定區(qū)域動植物聯(lián)系描述的專業(yè)術語都被批評，但“生態(tài)系統(tǒng)”越來越被廣泛接受，它用以描述相互聯(lián)系的有機體以及生態(tài)環(huán)境物理因素的系統(tǒng)。最終，這個系統(tǒng)強調的是能量轉變模式。因此生態(tài)系統(tǒng)包括通過生物媒介和活動而產生的循環(huán)、轉換和能量及物質的積累。生態(tài)學家主要關注的是在給定系統(tǒng)下流過系統(tǒng)的物質和能量的量以及它們流過的速率。
盡管生態(tài)系統(tǒng)的概念在二十世紀五六十年代特別流行，但它也不是最權威的范例。格里森反對頂級群落和生物群系的論點用來反駁生態(tài)系統(tǒng)同樣很有效。進一步講，交互的數量如此之大以至于即使借助計算機也很難去分析它們。最后，年輕一代的生態(tài)學家發(fā)現關于行為和生命歷史進化的問題比測試物理常量更有趣。盡管如此，當談到某地的動植物聯(lián)系的時候還是會使用生態(tài)系統(tǒng)，通常也就不關注能量的方面了。
