You should spend about 20 minutes on Questions 1-14 which are based on Reading Passage 1 below.

The History of Woodlands in Britain

The climate in Britain has been arctic for the last several million years, punctuated by relatively warm timespans, or interglacials of thousands of years, one of which we are in as of now. Since the last glaciation, British woodland history is considered quite short in terms of geological time spans, and is also closely related to the human civilization developing.

At the peak of the last glaciation (100,000 – 12,000 BC), the majority of Britain would have had no trees. Birch and willow scrub may have grown along the lower reaches of the ice, with pine in some areas. It’s possible that remnants of pre-glacial flora were sheltered along the western bays of Great Britain and Ireland’s coasts, but as far as the southern parts of England, the ice kept any land barren. Information regarding the development of Britain’s flora following glaciation can be found by studying the deposits of pollen and seed in peat, as well as by the use of radiocarbon dating. Tundra and moorland followed the retreating ice, which lead to phases of different tree species spreading from the south. First came birch, aspen and sallow, followed by pine and hazel continuing to spread north as of 8500 BC, replacing birch to make it less commonly found for the next few thousand years. Oak and alder came after pine, then lime, elm, beech, and maple, all spreading northwards one after the other. From the moment lime arrived, in about 7300, to about 4500 BC the climate remained stable for a length of time known as the Atlantic Period, a time in which numerous species grew to form a series of wildwood or wilderness types.

What did the wilderness or wildwood look like, before man started interfering with it? One theory holds that Britain and Western Europe in Palaeolithic times was covered from coast to coast in a wildwood of continuous trees. However, a modern theory proposed by Francis Vera holds that Western Europe wilderness was a combination of grassland, scrub, and clusters or groves of trees. It was not a dense, impassable wildwood, but instead, an area similar to a park, kept up by wild herbivores eating the plants and grass. Throughout earlier interglacial periods, this may also have been the case in Britain, as creatures of the Palaeolithic era needed to roam large areas of grassland to survive. A variety of grassland plants continued to live there in the last interglacial, as according to pollen records. However, since the last glaciation, the bison, elk and other large herbivores which persisted on mainland Europe were extinct in Britain, so Vera’s theory may not apply so well to Britain.

Meanwhile, throughout the period since it’s spread northwards after the last glaciation, the sustained growth of oak in Britain demonstrates that the wildwood was not as continual as once believed. Oak is a pioneer species, which requires vacant space to generate more of itself. Grazing animals are also present to keep areas open, so Oak regenerates in the thorny brush as a protective measure from their grazing. Archaeological evidence indicates that red deer, who graze on grass as well as browse from trees, were essential to the economy in Mesolithic Britain, with people utilizing them for meat, skins, antlers and bones.

As the Mesolithic (10,000-3000 BC) era ended, evidence of the beginnings of agriculture emerges. Agricultural weeds, such as plantain and stinging nettle, were also increasing in number. Nearly all the wildwood was cut down as the population increased rapidly. However, the falling elm population around 4,000 BC all across Europe has been attributed not to the clearing of trees, but to what’s referred to as Elm disease.

Throughout the Bronze Age (2400-750 BC), people were cutting down trees more than ever before, until the prevalence of the practice “coppicing” peaked, likely at some point during the early Iron Age. Oliver Rackham (1990) theorizes that nearly 50% of land throughout England was no longer wildwood by 500 BC. The regrowth from a stump grows more readily than the original tree, and Neolithic man had discovered this practice, known as coppicing. Much of the remaining woods were maintained by way of this method during the Bronze Age.

The Celtic peoples living in the Iron Age were able to master woodworking as an artform. Today, Celtic woodworking can be seen in houses, boats, wheels and other artifacts of the time. Coppicing as a means to manage woodland was of massive importance throughout two millennia that followed. Buildings, roads, fences, carts, and the fuel for heating, cooking, metalworking and pottery were all made possible due to wood materials gained from the vital practice of coppicing.

A clear divide has existed between wooded and non-wooded regions of Britain since the time of the Romans. As evidenced by The Domesday Book (1086), all the wood in England had an economic value and was the property of either an individual or community owner. Woods were the territories, or ‘exclaves’ of communities who lived some miles away. Even though it had to be transported over long distances, the materials which woodlands produced were of obvious value, and their ownership was long before established. Merely around 15% of land in England was represented by woodland or wood-pasture in the year 1086.

English woodlands produced mostly underwood used as fuel along with other things, with small oaks being used to construct buildings. The average wood-framed houses of the Medieval era mostly used oaks shorter than 18” in diameter. Longer pieces of timber were hard to come by, and kept only for elaborate buildings intended for the Church. Imported boards of thin oak or wainscot from Central Europe were brought in for the purpose of domestic building. Woodland cover was as low as 15% in 1086, and continued to decline from as a result of an ever-growing population to 10% by 1350. This stopped suddenly with the plague of the Black Death of 1349 wiping out some of the human population. Woods which had persisted up to 1350 mostly prospered over the next 500 years.

You should spend about 20 minutes on Questions 15-28 which are based on Reading Passage 2 below.

Succession and Ecosystems

A

Ecologists use the term “succession” to refer to the changes that happen in plant communities and ecosystems over time. 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, shrubs, and trees, eventually becoming a forest.

B

The first community in a succession is called a pioneer community, while the established community at the end of a succession is called a climax community. Pioneer and successional plant communities are said to change over periods of 1 to 500 years. These changes—in plant numbers and the mix of species are cumulative. Climax communities themselves change but over periods of time greater than about 500 years. The final stage of a succession is 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 community is influenced by the same factors that influence succession. Nevertheless, mature natural environments are usually in equilibrium. They change relatively little through time unless the environment itself changes. Clements and other early ecologists saw an 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 arbitrary processes.

C

For Clements, the climax community was a “superorganism,” an organic entity. Even some authors who accepted the climax community 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.

D

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 it would be with 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.

E

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. An 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. Today one speaks of the ecosystem when referring to a local association of animals and plants, usually without paying much attention to these energy aspects.

F

At one time, ecologists believed that species diversity made ecosystems stable. They believed that the greater the diversity the more stable the ecosystem. Support for this idea came from the observation that long-lasting climax communities usually have more complex food webs and more species diversity than pioneer communities. Ecologists concluded that the apparent stability of climax ecosystems depended on their complexity. To take an extreme example, farmlands dominated by a single crop are so unstable that one year of bad weather or the invasion of a single pest can destroy the entire crop. In contrast, a complex climax community, such as a temperate forest, will tolerate considerable damage from weather to pests.

G

The question of ecosystem stability is complicated, however. Stability can be defined as simply lack of change. In that case, the climax community would be considered the most stable, since, by definition, it changes the least over time. Alternatively, stability can be defined as the speed with which an ecosystem returns to a particular form following a major disturbance, such as a fire. This kind of stability is also called resilience. In that case, climax communities would be the most fragile and the least stable, since they can require hundreds of years to return to the climax state.

H

Even the kind of stability which is defined as simple lack of change is not always associated with maximum diversity. At least in temperate zones, maximum diversity is often found in mid-successional stages, not in the climax community. Once a redwood forest matures, for example, the kinds of species and the number of individuals growing on the forest floor are reduced. In general, diversity, by itself, does not ensure stability. Mathematical models of ecosystems likewise suggest that diversity does not guarantee ecosystem stability—just the opposite, in fact.

I

Many ecologists now think that the relative long-term stability of climax communities comes not from diversity but from the “patchiness” of the environment, an environment that varies from place to place supports more kinds of organisms than an environment that is uniform. A local population that goes extinct is quickly replaced by immigrants from an adjacent community. Even if the new population is of a different species, it can approximately fill the niche vacated by the extinct population and keep the food web intact.

You should spend about 20 minutes on Questions 29-40 which are based on Reading Passage 3 below.

Discoveries on the Basis of Deductive Reasoning

Could it be that the very essence of reasoning itself is found in the way we behave? Clark Hull, an acclaimed American psychologist, theorized that it was, describing that reasoning is achieved by the way two “behavior segments” are combined in new ways to achieve goals. Howard and Tracey Kendler, who were two of Hull’s followers, used Hull’s principle ideas to design a reasoning test for children. In this test, children needed to learn how to use a machine in a two-step process. The children learned each of the two steps individually, with the first being to correctly choose and press one of two buttons, and the second to place a marble into a small opening. If both steps were completed successfully, a toy would be released as rewards to the children.

From this test, the Kendlers learned that although the children were able to learn each step, they were not able to “integrate” the two tasks without intervention. In other words, the children could not successfully perform the first step, pushing the button, and then proceed to the second step, inserting the marble into the hole, by themselves. This failure to independently integrate the steps led the Kendlers to believe that children of this age were not able to use deductive reasoning.

According the the work of psychologist and professor Michael Cole and his associates, some adults from specific African tribes are also unable to successfully complete the Kendlers’ two-step test of deductive reasoning. However, this finding remains questionable in light of the findings of a similar test to the Kenders’, which revealed that the African tribes people were, in fact, able to complete the test.

In this test, Cole substituted a locked box for the machine with the buttons, and then used two matchboxes of different colors. One of the matchboxes held a key for the locked box. Just like with the Kendlers’ test, Cole’s test also involved two behavior segments, these being to first open the right match-box to get the key, and second to use the key to open the box. However, Cole’s test differs quite a bit psychologically. Instead of subjects being presented with a strange machine, they are given familiar objects in a simpler context. Cole found the difficulty of ‘integration’ was greatly reduced here.

It seems that the same truth which Cole discovered can be extended to explain the deductive reasoning skills of young children. Psychologist Simon Hewson believes that perhaps the task’s difficulty is not in inferential processes themselves, but is instead tied to confusing features of the test apparatus, such as the button machine, as well as the context of the procedure being tested. When these factors are adjusted in order to prevent the inferential nature of the problem being affected, five-year-old children are able to successfully complete these tests as well as college students did in the Kendlers’ test.

Hewson made two essential changes to the test in order to build on this idea. First, he replaced the button-pressing mechanism with drawers that a child could slide open and shut. This removed confusion on what to do with the original button apparatus from the first stage of training. Secondly, Hewson made sure that children understood that there was nothing special or magical about the marble which was used to successfully complete the second step of the task and get the reward.

This is important because a child cannot easily comprehend a mechanism in which a marble put into a hole can open a little door. It would then be safe to say that the child will not assume that any marble of similar size could be used the same way. But, to solve the problem, this assumption must be made. Hewson clearly demonstrated the functional equivalence of different marbles to the children by playing a ‘swapping game.” Hewson’s two modifications to the experiment led to a rise in success rates from 30 percent to 90 percent for five-year old children and from 35 percent to 72.5 per cent for four-year-olds. Strangely enough for three-year olds, Hewson’s changes did not lead to any improvement, and instead there was a slight drop in performance from the change. Hewson’s experiments showedthat children faced with the Kendler apparatus experienced difficulty not related to reasoning, but to the nature of the tasks themselves, and that difficulty cannot be taken as proof that they are incapable of deductive reasoning.