PT11.S4.Q11 - Logging industry official: Harvesting trees

moonstars5678

Am having trouble with this question - could someone let me know if I'm thinking about the stimulus (and ACs) correctly?

Stim:
P1: When old trees die, the decomposition releases their stored CO2
P2: Harvesting old trees makes more room for young trees (who can absorb more CO2 than old trees)
C: Harvesting old trees for manufacturing things would reduce CO2 (and therefore we'd avoid the whole decomposing issue?)

My thoughts: Okay, that seems like it makes relative sense. There's an assumption there that the CO2 release by decomposed old trees would be offset by the young trees that can absorb more CO2.

ACs:
A - Animal species? Irrelevant.

B - At first I immediately eliminated this AC because it just didn't seem to make any sense. After more reading, it seems like okay, if the harvested old trees were manufactured into products that would decompose super quickly, we could still run into the CO2 decomposition issue.

C - This was the AC I originally picked, thinking that since a young tree contains 10 CO2 vs an old tree that contains 40 CO2, then clearly the young tree can't offset the decomposition of an old tree. But I think this AC is actually irrelevant because of course a young tree at a snapshot would contain less CO2 than an old tree would - but this seems to attack P2?

D - Irrelevant, dont need to know where most of the CO2 in a forest comes from.

E - I feel like this AC is trying to get us to attack P2 in a similar way C is, but we'd have to also assume that size of trees has some sort of correlation with CO2 absorption.

help

mr.michaelgsavard-1-1-1-1-1

When I used "Lawgic" to diagram the stimulus, I came up with something very similar to what you have in your post.

P1 states that OldTreesDie-->Decompose-->Release CO2.
P2 (ultimately a useless premise) HarvestOldGrowthForest-->MoreYoungTreesGrow-->MoreEfficientTreesCapturingCO2
C states that HarvestForest(-->/Decomposition(=assumption))-->/Release CO2

ACs...
A--irrelevant
B--Correct, since it directly attacks the assumption that harvesting eliminates decomposition, which we learned decomposition causes the release of CO2. According to B, harvesting contributes to decomposition, which occurs after manufacturing of the tree into products--i.e., decomposition (and the release of CO2) occurs, but just later in the process.
C--The conclusion in the stimulus makes a claim about the amount of CO2 in the atmosphere, whereas AC C makes a statement about the amount of CO2 in a younger vs. older tree. If C is true, then the amount of CO2 in the atmosphere remains unknown, and possibly unchanged, with or without harvesting, since we don't know how many young vs. old trees there are.
D--A restatement of P1.
E--A tricky AC to easily eliminate, but it does not weaken the argument, since smaller trees over many years do not necessarily mean less CO2 capturing occurs as compared to before harvesting. In fact, younger trees are more efficient (P2) at capturing CO2, and their size does not necessarily contribute to their efficiency.