In the late nineteenthcentury,ecologybegan to grow into anindependentscience from its roots in naturalhistoryand plant geography. The emphasis of this new "communityecology" was on thecompositionand structure of communities consisting of differentspecies. In the early twentiethcentury, the American ecologist Frederic Clementspointedout that asuccessionof plant communities would develop after adisturbancesuch as avolcaniceruption, heavy flood, or forest fire. An abandonedfield, forinstance, will be invaded successively byherbaceousplants (plants with little or no woodytissue), shrubs, and trees,eventuallybecoming a forest. Light-lovingspeciesare always among the first invaders, while shade-tolerantspeciesappearlater in thesuccession.

Clements and other early ecologists saw almost lawlike regularity in the order ofsuccession, but that has not been substantiated. A generaltrendcan be recognized, but the details are usuallyunpredictable. Successionis influenced by many factors: the nature of the soil,exposureto sun and wind, regularity ofprecipitation,chancecolonizations, and many otherrandomprocesses.

The finalstageof asuccession, called theclimaxby Clements and early ecologists, islikewisenotpredictableor ofuniformcomposition. There is usually a gooddealof turnover inspeciescomposition,evenin amaturecommunity. The nature of theclimaxis influenced by the same factors that influencedsuccession. Nevertheless,maturenatural environments are usually inequilibrium. They changerelativelylittlethroughtime unless the environment itself changes.

For Clements, theclimaxwas a "superorganism," anorganicentity. Evensome authors who accepted theclimaxconceptrejected Clements' characterization of it as a superorganism, and it is indeed a misleadingmetaphor. An antcolonymay be legitimately called a superorganism because its communication system is so highly organized that thecolonyalways works as a whole and appropriately according to the circumstances. But there is noevidencefor such an interacting communicative network in aclimaxplantformation. Many authorsprefertheterm"association" to theterm"community" in order tostressthe looseness of theinteraction.

Evenless fortunate was theextensionof this type of thinking to include animals as well as plants. This resulted in the "biome," acombinationof coexistingfloraandfauna. 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 nointernalcohesionto theirassociationas in anorganism. The sprucecommunityis notsubstantiallyaffected by either the presence orabsenceof moose. Indeed, there arevastareas of spruce forest without moose. Theoppositionto the Clementsianconceptof plantecologywas initiated by Herbert Gleason, soon joined by various other ecologists. Theirmajorpoint was that thedistributionof agivenspecieswas controlled by thehabitatrequirements of thatspeciesand thatthereforethevegetationtypes were a simpleconsequenceof the ecologies ofindividualplantspecies.

With "climax," "biome," "superorganism," and various othertechnicalterms for theassociationof animals and plants at agivenlocalitybeing criticized, theterm"ecosystem" was more and more widely adopted for the whole system of associated organisms together with thephysicalfactors of their environment. Eventually, the energy-transforming role of such a system was emphasized. Ecosystems thus involve thecirculation,transformation, andaccumulationof energy and matterthroughthemediumof living things and their activities. The ecologist is concernedprimarilywith the quantities of matter and energy that passthroughagivenecosystem, and with the rates at which they do so.

Although theecosystemconceptwas verypopularin the 1950s and 1960s, it is no longer thedominantparadigm.

Gleason's arguments againstclimaxand biome are largelyvalidagainst ecosystems as well. Furthermore, the number of interactions is so great that they are difficult toanalyze,evenwith the help of large computers. Finally, younger ecologists have foundecologicalproblems involvingbehaviorand life-history adaptations moreattractivethan measuringphysicalconstants. Nevertheless, one still speaks of theecosystemwhen referring to alocalassociationof animals and plants, usually without

paying muchattentionto the energy aspects.

Questions:
question_stem: According to paragraph 2, which of the following is a criticism of Clements' view of succession?
choices: tag: A
text: The principles of succession are more lawlike than Clements thought they are.

tag: B
text: More evidence is needed to establish Clements’ predictions about succession.

tag: C
text: The details of succession are affected by random processes.

tag: D
text: 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.
answer_key: C
explanation: C 本段较短，可以快速扫完，也可以用人名和 succession 做关键词定位至最后一句，说很多因素都可以影响 succession，所以正确答案是 C。D 提到了 many factors，但 change 是原文没说的，错；A 的比较原文没说，错；B 是最具有迷惑性的选项，因为原文说没有被证实，也就是已经建立了只是没证实，但 B 说需要更多证据来建立 Clemens 的预测，也就是没建立，而且预测也不对，所以 A 错。

question_stem: The word “substantiated” in the passage is closest in meaning to
choices: tag: A
text: confirmed

tag: B
text: noticed

tag: C
text: defined

tag: D
text: publicized
answer_key: A
explanation: A substantiate: 证实，确认。A 是确证；B 是发现；C 是定义；D 是宣传。所以正确答案是 A 的 confirm。

question_stem: The word “trend” in the passage is closest in meaning to
choices: tag: A
text: probability

tag: B
text: picture

tag: C
text: lawlike regularity

tag: D
text: tendency
answer_key: D
explanation: D, trend: 趋势。A 是可能性；B 是图片，景色；C 是想法律一样的规则性；D 是趋势。所以 D 的 tendency 正确。

question_stem: The word “likewise” in the passage is closest in meaning to
choices: tag: A
text: sometimes

tag: B
text: similarly

tag: C
text: apparently

tag: D
text: consequently
answer_key: B
explanation: B likewise: 同样地，此外。A 是有时候；相似的；明显的；因此，结果。所以 B 的 similarly 是正确答案。

question_stem: The word “legitimately” in the passage is closest in meaning to
choices: tag: A
text: commonly

tag: B
text: broadly

tag: C
text: properly

tag: D
text: officially
answer_key: C
explanation: C 这道题很多同学误选 D. 其实，C properly 更好。前句说一些学者接受 Clements， 对于 climax 的 concept, 但拒绝 C 对于 climax 作为 superorganism 特征的概括。然后做了一个对比区分。An ant colony may 
be legitimately called a superorganism…. But there is no evidence for such an interacting communicative network in a climax plant formation. 这个对比区分的是两个范畴，动物的和植物的。如果把 legitimately 理解为 officially, formally,应该只举一个植物范畴的例子，构成“正式、官方、权威”和实际情况的转折。现在是两个范畴的对比，应该理解成： 一个领域“合理，有道理，正确”，另外一个领域“没有证据，没有道理”

question_stem: According to paragraph 4, why do many authors prefer the term “association” to “community” when describing a climax plant formation?
choices: tag: A
text: Because the term “association” does not suggest the presence of a tight network involving interactive communication.

tag: B
text: Because the term “association” indicates that the grouping is not necessarily beneficial to all members.

tag: C
text: Because the term “community” indicates continuing dynamic development that a climax formation does not have.

tag: D
text: Because the term “community” suggests an organization that has been designed for a specific purpose
answer_key: A
explanation: A 细节题题，先读修辞点所在句子，in order to 告诉你这句话中就含有目的了，将 in order to 后面的内容读了就找到答案，原句说为了强调这种互动的松散性，很多作者更愿意使用 association，原文都说了是为了强调松散性，所以答案是 A，不存在紧的 network。B 的 beneficial to all members，C 的 dynamic development 和 D 的 specific purpose 原文都没说。

question_stem: In paragraph 5, the author challenges the idea of a “biome” by noting that
choices: tag: A
text: there are usually no very strong connections among the plants and animals living in a place

tag: B
text: plants and animals respond in the same way to the same circumstances

tag: C
text: particular combinations of flora and fauna do not generally come about purely by chance

tag: D
text: some animals are dependent on specific kinds of plants for food
answer_key: A
explanation: A 以 biome 做关键词定位至第二句，由于这句只是给出了 biome 的概念，没有 challenge，所以往下看，下句说尽管有些动物与植物的关系是紧密的，但还是不能说 biome，比如他们之间没有 internal cohesion，所以答案是 A，动植物之间没有紧密关系。B 和 C 原文都没讲；D 的 food 原文也没说，而且 D 也不是 challenge 上文提到的概念的，所以不对。

question_stem: Why does the author make the statement, “Indeed, there are vast areas of spruce forest without moose” ?
choices: tag: A
text: To highlight a fact whose significance the ecologist Herbert Gleason had missed

tag: B
text: To propose the idea that a spruce forest is by itself a superorganism

tag: C
text: To emphasize that moose are not limited to a single kind of environment

tag: D
text: To criticize the idea of a spruce-moose biome
answer_key: D
explanation: D 修辞目的题，修辞点就是一个句子，所以看前一句，前句说 spruce 种群不受 moose 是否存在的影响，依然还是一个例子，所以看中心句，注意这段文字的中心句不是第一句，而是上一题中提到的第二句，说 spruce-moose biome 是不对的，所以答案是 D。

question_stem: The word “initiated” in the passage is closest in meaning to
choices: tag: A
text: approved

tag: B
text: identified

tag: C
text: started

tag: D
text: foreseen
answer_key: C
explanation: C  initiate: 开始，首创。A 是同意；B 是核实；C 是开始；D 是预见。所以正确答案是 C 的 started。

question_stem: 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
choices: tag: A
text: they can enter into mutually beneficial relationships with other species

tag: B
text: conditions suit them, regardless of whether particular other species are present

tag: C
text: habitats are available for a wide variety of plant and animal species

tag: D
text: their requirements are met, and those of most other species are not
answer_key: B
explanation: B 以 Christian 和 species 做关键词定位至最后两句，倒数第二句说反对，最后一句说反对的原因，物种的分布取决于环境，只是自身生态学的结果。也就是跟其他物种无关，所以答案是 B。既然说跟其他物种无关，A 和 D 就不对，C 也说了大量物种，与原文不同。

question_stem: 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.
choices: tag: A

tag: B
text: 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.

tag: C
text: When the older terms of ecology became too technical, they were replaced by the more popular and more widely used term "ecosystem."

tag: D
answer_key: D
explanation: D 原句当中的 with 结构是非主要成分，主要成分是：采用了 ecosystem 形容生物和环境的 associated system，正确答案 D。A 的后半句错，eco 不是单只 physical factor，而是系统;B 和 C 都错在将原句的主干和非主干混合，不选。

question_stem: According to paragraph 6, what did ecologists mainly study when the ecosystem concept was the dominant paradigm?
choices: tag: A
text: The physical factors present in different environments

tag: B
text: The typical activities of animals and the effect of those activities on plants

tag: C
text: The rates at which ecosystems changed from one kind to another

tag: D
text: The flow of energy and matter through ecosystems
answer_key: D
explanation: D，以 ecologist 做关键词定位至最后一句，说生态学家最关注的是特定生态系统里物质与能量的传递及其速率，所以答案是 D。A 和 B 都没说，C 的 rate 原文有说，但原文说的是物质和能量传递的速率，不是答案说的 ecosystem 改变的速率，所以 C 错。