#13 - Mature white pines intercept almost all the sunlight

[Kayla737]

Hi,

After reading the comments I am still very confused as to how from the stimulus we can conclude that the trees, although in the same area, did not get germinated at different times. Within one stand could there not be trees that also have access to sunlight but are germinated later, and therefore making them younger?

Thanks in advance!

[Robert Carroll]

Kayla,

The stimulus has already "baked in" the idea that we are dealing with a dense forest. Once you have mature white pines, no sunlight will get to any lower tree, so once maturation occurs, any tree that hasn't yet started growing is out of luck. That's why in answer choice (A) it's key that the age difference between trees CAN be as long as it takes a pine to mature, but no longer. Between the initial growth of one of these trees and its reaching maturation, other pines could grow, but, if the difference in ages is longer than that, a newly-growing tree will be prevented from growing by the already-mature trees out there.

Robert Carroll

[ericsilvagomez]

Hi,

For this problem, I guessed A because the last sentence says, "A stand of trees consists of nothing but mature white pines." Was I correct in using that logic to make that guess? I did not understand the language of much of the stimulus, and the stimulus did not seem to support the other answer choices as much.

[Robert Carroll]

ericsilvagomez,

There's no need to make a guess. If light doesn't get through, then once the trees are mature, no new trees will really be able to grow underneath them. So the "new" trees have to grow before the "old" trees block out all the light, which will limit the age differences among the trees pretty severely.

What in the stimulus didn't you understand?

Robert Carroll