Integrated essay

As a matter of the fact decreasing the yellow cedar trees which are common in northwestern North America, is a controversial issues among the ecologists. The reading explains three hypotheses for this phenomenon, whereas the lecturer brings some arguments to reject them.

The firs hypothesis which is explained in the reading is that a kind of insect which is called beetle is the reason of declining cedar trees. The larvae of beetles eat the trees and killing it, on the other hand the speaker refutes it by explaining that those insects attack to the damage trees which already are so weak to survive and there are plenty of healthy cedar trees destroy without any insects in them.

The second hypothesis which is illustrated in the reading is that brown bears eat the tree bark which is contain a lots of sugar and this action make trees weak and they can’t tolerate against hardship anymore, in spite of the fact that the professor says the cedar trees start to decline even on those places without any bears, so the brown bear is not a good explanation to this fact.

The last hypothesis which is mentioned in the reading is that changing in climate might be the reason of these reduces. Because the roots start to grow in the late winter instead of spring and the coldness of winter’s night might be heart the roots and eventually kill the tree, although the lecturer believe that it is not convenient explanation because if this is true it is expected to see more trees dying in cold weather in high elevation, while the most of tress died in warm places in low elevation.