TPO23

In this set of materials, the reading passage and the lecturer discuss the possible reasons that cause declining of yellow cedar trees. Although the reading passage provides tree theories about the reasons for the decline of yellow cedar trees, the speaker refutes this idea through several reasons which I will describe in this reporter.

First, the reading discusses that some insects such as beetle may kill the yellow cedar trees. The beetle attack to the trees and eat the larvae of the wood, and they may be caused by the decline of trees. However, the lecturer, in contrast, rejects this by claiming that the healthy yellow cedar trees produced the saturated power liquid that was poisoning for beetles. So, the beetles cannot attach the trees. But, if the trees became sick and diss, they would not produce chemical liquid to protect themselves. In these situations, the beetles can attack the trees. As a result, another reason may the causes for declining the yellow cedar trees.

Second, the reading passage argues that the beer claw at the cedar trees, because the cedar trees produced the sweet liquid that is a staple of bears diet, the damage on the trees became weaken the trees and they died. But, the professor argues that the yellow trees were died on the North and West America, in the mainland and islands. In islands, the bear did not leave, but the yellow cedar trees were killed. So, the bear cannot the reason for declining the yellow cedar trees.

Finally, although the reading passage says that gradual changes of climate may be the cause of this reduction, the professor disagrees by mentioning that more yellow cedar trees are dying in lower elevations which have a warmer climate than the higher elevation. Thus this declining pattern counters the hypotheses of climate change role in yellow cedars' population decrease.