Populations of the yellow cedar, a species of tree that is common in northwestern North America, have been steadily declining for more than a century now, since about 1880. Scientists have advanced several hypotheses to explain this decline.One hypothesis

Both the reading and the lecture discuss three hypothesis that whether explains the decline of Yellow Cedar Trees or not. Whereas, the reading support three reasons, the listener disregards those reasons and rather focuses in other aspects.

First in the reading the author claims that the Yellow Cedar trees might have decreased their population because an insect parasite known as bear beetle has harmed them. Notwithstanding, the listener doesn't agree with this idea, in lieu, he explains that healthy Yellow Cedar trees are resistant to insects or any other pests attacks. Due to the fact that Yellow trees naturally poses a chemical solution that is toxic for insects. Therefore, the opposite happens when the Yellow Cedar trees are sick, their defenses are reduced and thus, they become vulnerable to pests.

Second, the article says that Brown Bears might be responsible for the Yellow Cedars reduction. On the other hand, the listener averts this point and states that this is not the cause due to the fact that in some areas where Brown Bears are not present, the Yellow Cedar trees have been affected as well. Instead, the listener thinks that the cause might rely in other factors.

Third, the reading states that the climate might also be another aspect that should be assessed as the responsible of this problem because trees' roots are vulnerable to freezing. Nevertheless, the listener claims another idea. He says that in some regions where trees are located in warmer zones, the same thing is happening, so warmer doesn't influence anything. In addition, trees in higher elevations are also affected due to the same problem.