Logging industry official: Harvesting trees

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Logging industry official: Harvesting trees

by pnk » Tue Jul 06, 2010 7:35 am
Logging industry official: Harvesting trees from old-growth forests for use in manufacture can reduce the amount of carbon dioxide in the atmosphere, since when large old trees die in the forest they decompose, releasing their stored carbon dioxide. Harvesting old-growth forests would, moreover, make room for rapidly growing young trees, which absorb more carbon dioxide from the atmosphere than do trees in old-growth forests.

Which one of the following, if true, most seriously weakens the official's argument?

(A) Many old-growth forests are the home of thousands of animal species that would be endangered if the forests were to be destroyed.
(B) Much of the organic matter from old-growth trees, unusable as lumber, is made into products that decompose rapidly.
(C) A young tree contains less than half the amount of carbon dioxide that is stored in an old tree of the same species.
(D) Much of the carbon dioxide present in forests is eventually released when wood and other organic debris found on the forest floor decompose.
(E) It can take many years for the trees of a newly planted forest to reach the size of those found in existing old-growth forests.

[spoiler]LSAT; OA later[/spoiler] Pls give explanations & if possible time taken to solve
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by albatross86 » Tue Jul 06, 2010 8:23 am
Time taken: 50 seconds

Summary of the argument:
Trees from old-growth forests can be harvested for use in manufacture - this will reduce atmospheric CO2 since
1. when such large old trees die they decompose and release CO2.
2. this would make room for young fast-growing trees which absorb more CO2.

WEAKENER

A. Animals would be endangered - irrelevant to argument which is about CO2 specifically.

B. Most of the organic matter from old trees is unusable as lumber and is made into products that decompose rapidly - EXACTLY - this weakens our argument which says that CO2 will be reduced due to this decomposing being avoided. However even after manufacturing processes, if the products made from such trees themselves decompose, this CO2 will be released anyway, thus weakening the justification.

C. This supports point 2 and seems to strengthen rather than weaken.

D. This simply restates that wood/debris decompose to release CO2 - this doesn't weaken the argument that harvesting old trees could reduce CO2 levels.

E. Young trees take many years to reach the size of old trees - so what? What has this got to do with the CO2 levels?

Pick B.
~Abhay

Believe those who are seeking the truth. Doubt those who find it. -- Andre Gide

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by pnk » Tue Jul 06, 2010 9:21 am
albatross86 wrote:Time taken: 50 seconds

Summary of the argument:
Trees from old-growth forests can be harvested for use in manufacture - this will reduce atmospheric CO2 since
1. when such large old trees die they decompose and release CO2.
2. this would make room for young fast-growing trees which absorb more CO2.

WEAKENER

A. Animals would be endangered - irrelevant to argument which is about CO2 specifically.

B. Most of the organic matter from old trees is unusable as lumber and is made into products that decompose rapidly - EXACTLY - this weakens our argument which says that CO2 will be reduced due to this decomposing being avoided. However even after manufacturing processes, if the products made from such trees themselves decompose, this CO2 will be released anyway, thus weakening the justification.

C. This supports point 2 and seems to strengthen rather than weaken.

D. This simply restates that wood/debris decompose to release CO2 - this doesn't weaken the argument that harvesting old trees could reduce CO2 levels.

E. Young trees take many years to reach the size of old trees - so what? What has this got to do with the CO2 levels?

Pick B.
Thanks Abhay; Great explanation OA - B