#5 - Concept Reference, Must Be True

[Administrator]

Complete Question Explanation

(See the complete passage discussion here: lsat/viewtopic.php?t=14220)

CR, Must. The correct answer choice is (B)

This question asks about ancient ponderosa forests, which are discussed in the first paragraph
as an example of forests whose stability was maintained partly by low-intensity fires that periodically
cleared out the younger trees and brush, leaving lower levels of fuel remaining, along with the more
mature trees,

Answer choice (A): The author does not discuss or allude to any genetic differences between ancient
ponderosa trees and their modern descendants, so this choice cannot be confirmed by the information
in the passage and thus fails the Fact Test.

Answer choice (B): This is the correct answer choice. The ancient ponderosa forests derived the
benefits of periodic fires that served to clear out the younger trees. The author also provides that
current firefighting techniques are so effective that many forests have gone 50 years without such
a fire. Presumably, then, modern ponderosa forests would be likely to be more dense than ancient
forests.

Answer choice (C): It’s possible that weather patterns were different in ancient poderosa forests, but
that issue is not discussed in the passage, so this choice can be safely ruled out of contention.

Answer choice (D): There is no information in the passage to support the assertion that the ancient
ponderosa forests had greater diversity than their modern counterparts, so this cannot be the right
answer to this Must Be True question.

Answer choice (E): This was likely a tempting answer choice for those who read through the passage
too quickly. The author does provide that large fires can be dangerous to wildlife, and that smaller
fires help to control the potential for larger fires, but the author doesn’t mention whether smaller fires
are able to provide wildlife population control.

[Cking14]

Hi,

I chose answer choice (D) for this one. Can someone please explain answer choice (B)? How is it that the population density was LESS, when, in the first paragraph it says that the forests where the ponderosas were are stable - up until the fires were trying to be contained/controlled? I chose (D) because it made more sense that there would be more of a variety had the fires not been controlled in the first place.

Thanks!
Chris

[Steve Stein]

Hi,

That's a good question; it asks about ancient ponderosa forests, which are discussed in the first paragraph of the passage as an example of forests whose stability was maintained partly by low-intensity fires that periodically cleared out the younger trees and brush, leaving lower levels of fuel remaining.

So, the ancient ponderosa forests derived the benefits of periodic fires that served to clear out the younger trees, and the author also mentions that current firefighting techniques are so effective that many forests have gone 50 years without such a fire. Presumably, then, modern ponderosa forests would be likely to be more dense than ancient forests, as answer choice (B) provides, since modern forests would not have derived the benefits of the periodic fires that served to clear out the younger trees and brush. The problem with answer choice (D) is that there's no information in the passage to support the notion that the ancient ponderosa forests had greater diversity than their modern counterparts.

I hope that's helpful! Please let me know whether this is clear--thanks!

~Steve

[Cking14]

OOOHH!!! Ok, got it! Thank you! RC is my worst section! But thanks so much! I see it!

[emilysnoddon]

I was choosing between answer choice B and E but went with E because I felt as though B would not necessarily be true considering it is a more mature tree, thus would remain alive during the fires. I didn't see where the support for the fact that the population density would be lower. I thought perhaps the density of the brush, yes, but not necessarily the population of the tree as a whole int he forest. Can someone please explain where I went wrong?

I chose E because I thought that line 14 supported it -- that by learning the understory of brush and young trees the wildlife populations would be controlled. I see where E has weaknesses but I thought it was the best answer.

Any help would be appreciated. Thank you!

Emily

[Shannon Parker]

Hello,

Yeah, that can get a little tricky. The key here is that the passage focuses on the fact that low-intensity fires cleared the brush and young trees from forests without harming the more mature trees, and thus reducing the population density. I think you may have misread line 14, which states, "these fires burned lightly around the bases of mature trees, leaving these trees alive and clearing the understory of brush and young trees." This is tricky because we would expect that these fires would control wildlife populations, but we have to stick to what the passage gives us, and the passage doesn't tell us anything about that, therefore we cannot pick (E).

-Shannon