Ecosystems can fight back

 

	GENERAL TRAINING READING ANSWERS
	READING PASSAGE 3 (THREE)
28	E
29	B
30	A
31	D
32	C
33	20 years
34	damage
35	ecological recovery
36	a forest
37	landscapes
38	state
39	targets
40	conservationists

 

 

SECTION3                Questions 28 – 40

Read the text and answerQuestions 28 – 40

Ecosystems can fight back

1. Conventional wisdom is often a poor guide. For one thing it suggests that human damage to the world’s species, habitats and ecosystems is terminal: that when things are lost, they are lost forever. But oil spills of the sort that now threaten the Timor Sea, forest fires like those that recently afflicted Greece, and other man-made and man-assisted threats to wildlife are transient. Except in those cases in which a species is driven to extinction, the Earth’s ability to shrug such things off is often underestimated.
2. Alan Weisman shows this in his book, “The World Without Us”, which illustrates nature’s great capacity to recover. Have mankind abducted by aliens or wiped out by some Homo sapiens-specific virus, and nature, Mr. Weisman reckons, would reclaim its territory with surprising speed, as weeds colonized pavements, rivers flooded subway tunnels and buildings burst as they were played like concertinas by a cycle of freezing and thawing. By Mr. Weisman’s reckoning, residential neighborhoods would return to forest in 500 years and only the most stubborn of human inventions, such as certain plastics, would prove permanent.
3. Mr. Weisman’s conclusion was backed up earlier this year by a study published in the Public Library of Science by Holly Jones and Oswald Schmitz, of Yale’s School of Forestry and Environmental Studies. They used Web of Science, an online journal archive, to gather a set of 240 peer-reviewed scientific papers that measured recovery rates in large terrestrial and aquatic ecosystems. The data thus available included work on agriculture, deforestation, the introduction of invasive species, logging, mining, oil spills, overfishing and the damage done to seabeds by trawling, as well as, for comparison, naturally occurring disasters such as hurricanes.
4. The pair measured 94 aspects of how ecosystems are put together, including the ways in which nutrients cycle within them, the rates at which decomposition rakes place and the sizes of their plant and animal populations, so that they could classify whether, and how fast, an area had recovered. They found that 83 of the 240 papers demonstrated complete recovery, while 90 showed a mixed response. Only 67 showed no recovery at all and, as the authors explain, more would have recovered if the projects had continued for long enough to track the changes in ecosystems that respond more slowly, such as forests.
5. Ecosystems exposed to more than one pressure, such as a forest that is first felled and then used for agriculture, took the longest to recover. Even in those cases, though, the average recovery time was, at 56 years, within a human lifetime. Sites that experienced single threats typically recovered in less than 20 years. The researchers found that recovery rates are influenced more by the type of ecosystem than by the magnitude of the damage inflicted upon it. Forests, for example, take longer to renew (42 years) than ocean floors (typically less than ten) regardless of the scale of the stresses inflicted on them.
6. Some commentators are sceptical about such positive findings. They point out that, of necessity, the study’s retrospective methodology includes papers published before researchers were required to declare any competing interests.This may have allowed, for example, an oil company to produce a report that plays down the damage done by a spillage. But such biased individual reports would be unlikely to affect the overall findings of a large study like this one.
7. Critics also question whether total ecological recovery really has been achieved as often as Ms. Jones and Dr. Schmitz suggest, and point to examples where it manifestly has not, such as the cod fishery of the Grand Banks, off the coast of Newfoundland, which collapsed in 1992. Almost two decades on, the cod show no sign of recovery, perhaps because new predators, such as dogfish, now dominate the waters.
8. It is true, though, that the question of what is pristine or natural can be debatable. A good example of this, which Mr. Weisman uses in his book, is Dartmoor, a national park in the south-west of England. Dartmoor is considered by many to be one of Britain’s great nature wildernesses. In fact, it is a human construction, formed by tens of thousands of years’ worth of alterations such as burning and agriculture. But it is in its current state, rather than as the forest it once was, that people wish to preserve it. Ms. Jones and Dr. Schmitz point out that most conservation work is not actually concerned with returning landscapes to their natural or prehuman states and “instead use contemporaneous reference systems as targets”.
9. Despite their study’s limitations, and the difficulty of measuring recovery and choosing targets, Ms. Jones’s and Dr. Schmitz’s findings are good news for conservationists. But the final word of advice belongs to Mr. Weisman as he invites people to ponder an alternative to his post-human future: “Since were imagining, why not dream of a way for Nature to prosper that doesn’t depend on our demise?”

 

 Questions 28 – 40

The text has nine paragraphs, A – L

Which paragraph contains the following information?

 

28. the main factor affecting recovery rates
29. a picture of urban life taken over by nature
30. examples of environmental damage caused by humans
31. positive results from a study
32. the kind of information gathered from scientific records

Complete the sentences below.

Choose NO MORE THAN TWO WORDS and/or a NUMBER from the text for each answer.

 

33. Approximate recovery time for ecosystems which experience no more than one pressure is _________________
34. Some critics claim the positive results may be influenced by some companies understating the _________________ they have caused.
35. The cod fishery of the Grand Banks is an example of where there has not been a complete _________________
36. Dartmoor was originally ___________________

Complete the summary below.

Choose NO MORE THAN ONE WORD from the text for each answer.

Ms. Jones and Dr. Schmitz believe that people are more interested in preserving or returning (37______________) to a present-day condition rather than to their original (38______________). However, despite the problems with (39 ________________) and recovery measurement, this latest study is a source of optimism for (40 _________________).