Read the following passage.
A. Fire is a vital and natural part of Canada's boreal forest, and many plants and animals depend on it. Most wildland fires there are started by lightning. The forest is a mosaic of stands, ranging from pure deciduous stands through mixed woods to pure coniferous ones, and its diversity comes mainly from the many fires that have swept the landscape over a long period. Fire is considered as crucial to forest renewal as the sun and precipitation. Burning releases nutrients stored in the litter on the forest floor and opens the canopy, so sunlight can reach new growth.
B. After a fire, the forest regrows with pioneer species such as aspen, white birch, jack pine and lodgepole pine, which all need full sunlight. Aspen and birch sprout quickly from the stumps and roots of burned trees. Jack pine and lodgepole pine carry their seeds in cones sealed by a waxy coating that only extreme heat can open, and the burn helps those seeds by leaving bare soil. If no fire returns within 100 years, the pioneer trees die and are replaced by black spruce growing beneath them. Balsam fir and white spruce are not adapted to fire and come back from seeds blown or carried in from unburned areas.
C. A region's fire regime is the pattern of its fires over time: their frequency, size, season, severity and cause. Across Canada, more than 8,000 wildland fires burn over 2.1 million hectares in an average year. Most go out or are contained before reaching 200 hectares, yet the larger ones make up about 97 per cent of the area burned. Since comprehensive monitoring began in 1959, both the yearly burned area and the number of large fires have increased. A far longer record from the Whiteshell region points the other way: lake sediments show that less wood burned over the past 2,500 years.
D. Jack pine is considered a species that regenerates well after fires of any severity. Yet after the Richardson Fire burned 576,000 hectares of forest dominated by jack pine in northern Alberta in 2011, researchers found that young stands under 30 years old that had burned severely held only about 1,164 seedlings per hectare, well below the density of stands that had not burned. Where two fires strike less than 15 years apart, young conifers can die before producing mature seeds. Scientists cannot yet say whether such areas, left alone, will return to jack pine, aspen and birch or become open woodland with far fewer trees.
E. Not given in any of the above paragraphs.
Decide which paragraph, A to D, has the information given in each statement below. Select E if the information is not given in any of the paragraphs.
AI explanationShows the answer. Tap to open.
Correct Answer: C
Why this is correct: The third paragraph says most fires go out or are contained before they reach 200 hectares. Yet the larger ones make up about 97 per cent of the area burned. So the larger fires, fewer than half of the total, do almost all of the burning.
Passage Reference: Most go out or are contained before reaching 200 hectares, yet the larger ones make up about 97 per cent of the area burned.
Tips: Look for a comparison between small fires and big fires. Then check which group causes almost all of the damage to the land.
Why the other options are wrong:
- A: The first paragraph explains why fire belongs in the boreal and what starts it. It never splits fires into small and large ones.
- B: The second paragraph follows which trees come back after a burn. It gives no figures on how much land fires cover.
- D: The Richardson Fire in paragraph D was huge. But that paragraph talks about one fire, not the share of burning done by big fires overall.
- E: Paragraph C gives the split: many small fires, and a few large ones that burn about 97 per cent of the area.
Correct Answer: E
Passage Reference: Yet after the Richardson Fire burned 576,000 hectares of forest dominated by jack pine in northern Alberta in 2011, researchers found that young stands under 30 years old that had burned severely held only about 1,164 seedlings per hectare, well below the density of stands that had not burned.
Why this is correct: The fourth paragraph reports that researchers found few seedlings in young stands after the Richardson Fire. It never says who those researchers were or who they worked for, so nothing links the count to Alberta government staff.
Tips: The fourth paragraph says what was found after the Richardson Fire. Check whether it says who did the finding.
Why the other options are wrong:
- A: The first paragraph is a general picture of fire in the boreal. It names no single fire, no place in Alberta and no survey team.
- B: Regrowth appears in Paragraph B only as a general pattern of which trees come first. Nobody counts anything there.
- C: Notice that paragraph C gives national figures and the Whiteshell record. The Richardson Fire and its seedling survey are not part of it.
- D: The fourth paragraph is the closest, because it describes the seedling count itself. But the people who did it are called only researchers.
Correct Answer: C
Passage Reference: A far longer record from the Whiteshell region points the other way: lake sediments show that less wood burned over the past 2,500 years.
Why this is correct: The third paragraph describes a far longer record from the Whiteshell region. Lake sediments show that less wood burned there over the past 2,500 years. That is a fall across many centuries in that one area.
Tips: Two trends about burning sit side by side in one place. Match this statement to the one that covers a much longer span of time.
Why the other options are wrong:
- A: The first paragraph says fires have swept the landscape over a long period. It does not say whether burning grew or shrank.
- B: Paragraph B deals with regrowth, such as spruce taking over after 100 years without fire. It keeps no long record of burning.
- D: The fourth paragraph looks at poor regrowth after recent fires in Alberta. It is not a history of burning that goes back thousands of years.
- E: Lake sediments from the Whiteshell region, showing less wood burned over 2,500 years, close Paragraph C.
Correct Answer: B
Passage Reference: If no fire returns within 100 years, the pioneer trees die and are replaced by black spruce growing beneath them.
Why this is correct: In paragraph B, the writer explains what happens if no fire returns within 100 years. The pioneer trees die, and black spruce growing beneath them takes their place. The first trees after a burn lose out when fire stays away.
Tips: Two places describe the forest after a fire. Ask which one explains what happens when fire stays away for a long time.
Why the other options are wrong:
- A: The first paragraph says fire renews the forest in general but does not describe one kind of tree taking over from another.
- C: Notice that paragraph C measures how much and how often the land burns, with no word on which trees replace which.
- D: The fourth paragraph also asks what grows back, but there the worry is fires coming too often, not staying away too long.
- E: Black spruce replacing the pioneer trees when fire stays away for 100 years is explained in Paragraph B.
Correct Answer: D
Passage Reference: Yet after the Richardson Fire burned 576,000 hectares of forest dominated by jack pine in northern Alberta in 2011, researchers found that young stands under 30 years old that had burned severely held only about 1,164 seedlings per hectare, well below the density of stands that had not burned.
Why this is correct: Look at paragraph D: it says jack pine is considered a species that regenerates well after any fire. Yet after the Richardson Fire, young stands that burned severely had only about 1,164 seedlings per hectare. That is far below the density of stands that had not burned.
Tips: Jack pine turns up more than once. Look for the place where it grows back poorly after a severe burn.
Why the other options are wrong:
- A: Look at paragraph A: it presents fire as a force of renewal and does not mention any tree failing to come back.
- B: Jack pine appears in Paragraph B with its heat-sealed cones, which help it regrow. Poor regrowth after a severe burn is not mentioned.
- C: The number, size and history of fires fill paragraph C. How well any one tree regrows is not discussed.
- E: The weak return of young jack pine stands after the severe Richardson Fire is reported in Paragraph D.
Correct Answer: E
Passage Reference: If no fire returns within 100 years, the pioneer trees die and are replaced by black spruce growing beneath them.
Why this is correct: Notice that paragraph B says that when no fire returns within 100 years, black spruce replaces the pioneer trees. It says nothing about how tall any of these trees grow, so the height comparison is never made.
Tips: Look at paragraph B: it tells you which tree takes over. Check whether it also says anything about size.
Why the other options are wrong:
- A: The first paragraph names no tree species at all. It talks about deciduous and coniferous stands in general.
- B: Black spruce does take over in the second paragraph, so it comes closest. But the passage never compares its height with the pioneers.
- C: The fire record and the Whiteshell study fill Paragraph C. Black spruce does not appear.
- D: Look at paragraph D: it discusses jack pine, aspen and birch after repeated fires and never mentions black spruce or tree height.
Correct Answer: A
Passage Reference: The forest is a mosaic of stands, ranging from pure deciduous stands through mixed woods to pure coniferous ones, and its diversity comes mainly from the many fires that have swept the landscape over a long period.
Why this is correct: The first paragraph says the boreal is a mosaic of deciduous, mixed and coniferous stands. Its diversity comes mainly from the many fires over a long period. Variety means diversity, and burning is the cause.
Tips: Fire is part of every paragraph. Ask which one explains why the forest is not all one type of tree, and names fire as the reason.
Why the other options are wrong:
- B: The second paragraph lists several trees that return after a fire. It does not say fire is the reason the forest is so varied.
- C: Notice that paragraph C describes patterns in the fires themselves and never links them to the mix of trees.
- D: In Paragraph D a burned area might end up with far fewer trees, which is the opposite of explaining the forest's variety.
- E: The link between the forest's diversity and the many fires over a long period is made in Paragraph A.
Correct Answer: B
Passage Reference: Jack pine and lodgepole pine carry their seeds in cones sealed by a waxy coating that only extreme heat can open, and the burn helps those seeds by leaving bare soil.
Why this is correct: In paragraph B, jack pine and lodgepole pine carry their seeds in cones sealed by a waxy coating. Only extreme heat can open them. Until that heat comes, the seeds stay locked inside.
Tips: Seeds come up in two places. Scan for the one that links them to heat.
Why the other options are wrong:
- A: Paragraph A says burning releases nutrients and lets in sunlight. It does not say heat opens anything.
- C: The third paragraph covers fire counts and records. Seeds and cones are not part of it.
- D: Look at paragraph D: it mentions seeds, but there young conifers die before they can produce them. Heat opening cones is not discussed.
- E: The waxy cones of jack pine and lodgepole pine, which open only with extreme heat, are described in Paragraph B.
Correct Answer: E
Passage Reference: Since comprehensive monitoring began in 1959, both the yearly burned area and the number of large fires have increased.
Why this is correct: Notice that paragraph C says the number of large fires has increased since comprehensive monitoring began in 1959. It does not say by how much, so the idea of a doubling goes beyond the text.
Tips: Notice that paragraph C says large fires increased. Ask whether it tells you how much.
Why the other options are wrong:
- A: The first paragraph explains what starts fires and what they do for the forest, with no count of fires over the years.
- B: The second paragraph is about seeds, sprouting and which trees follow which, not the number of fires.
- C: The third paragraph comes closest, since it reports a rise in large fires since 1959, yet it never says the number doubled.
- D: Look at paragraph D: it covers one huge fire and repeat burns, but it gives no national trend in large fires.
The rest of this explanation is for members. Sign in free to read why the other options are wrong, key words and tips.
Sign in to read the full explanation