TPO 23

The passage talks about three reasons which can contribute to a reduction in the population of the yellow cedar trees. However, the professor states that these reasons are not adequate and refutes all of them.

To begin with, the passage mentions bark battles as a reason for yellow cedar trees declination. The professor rejects this reason. He says that healthy yellow cedar trees are saturated with a chemical which is poisonous for this kind of insect. Consequently, this substance protects healthy trees. He concludes that cedar bark beetle attaches cedar trees which already sick and will die anyway.

Second, the passage states that brown bears eat the tree bark which can cause a reduction in the number of yellow cedar trees. The professor opposes this point. He says that yellow cedar trees decline in both mainland and island while no bears live in the island. That is a steady evidence against the claim of bear"s responsibility in trees reduction.

Finally, the passage notes that gradual climate change may be responsible in this matter. Cold weather affects the root system of these trees contributes to killing the tree. In contrast, the professor mentions that more quantity of trees dies in lower elevations which have a warmer weather. As a result, cold weather and climate change may not take part in dying of the yellow cedar trees.