Essay topics: 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 is that the yellow cedar decline may be caused by insect parasites, specifically the cedar bark beetle. This beetle is known to attack cedar trees; the beetle larvae eat the wood. There have been recorded instances of sustained beetle attacks overwhelming and killing yellow cedars, so this insect is a good candidate for the cause of the tree’s decline.
A second hypothesis attributes the decline to brown bears. Bears sometimes claw at the cedars in order to eat the tree bark, which has a high sugar content. In fact, the cedar bark can contain as much sugar as the wild berries that are a staple of the bears’ diet. Although the bears’ clawing is unlikely to destroy trees by itself, their aggressive feeding habits may critically weaken enough trees to be responsible for the decline.
The third hypothesis states that gradual changes of climate may be to blame. Over the last hundred years, the patterns of seasonal as well as day-to-day temperatures have changed in northwestern North America. These changes have affected the root systems of the yellow cedar trees: the fine surface roots now start growing in the late winter rather than in the early spring. The change in the timing of root growth may have significant consequences. Growing roots are sensitive and are therefore likely to suffer damage from partial freezing on clod winter nights. This frozen root damage may be capable of undermining the health of the whole tree, eventually killing it.
Both the reading and the article discuss the causes of the steady decline of yellow cedar populations in northwestern North America. The reading asserts three possible hypotheses for this decline; insects, brown bears and climate change. However, in the lecture, the professor refutes each of those hypotheses and says that the reason of this decline is still unknown and non of the reading’s explanations are adequate.
First, the reading states that the decline may be caused by insect parasites, specifically the cedar bark beetle. The professor contradicts this point by saying that healthy trees are more resistant to insect damage. He says that healthy trees are saturated by a powerful chemical, which is toxic for insect. Therefore, insects can only attack trees which are already damaged, trees which would die anyway. Thus, insects cannot be the cause of this decline.
Second, the reading pushes forth the idea that the brown bears would be responsible for the decline, since bears sometimes claw at the cedars to eat tree’s barks. The professor rejects this by saying that the population of cedar trees have been declined all across the inland, in both places with and without brown bears. Therefore, the brown bears cannot be responsible for the decline.
Finally, the reading implies that gradual changes of the climate may be a good hypothesis. The professor contents this by saying that the reading forgot to take one fact into account. The trees’ population have been decrease in lower elevated places, where the weather is warmer, more that the higher elevated places. Consequently, the change of weather cannot be blamed, because evidence do not support this hypotheses.
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Sentence: Consequently, the change of weather cannot be blamed, because evidence do not support this hypotheses.
Description: A determiner/pronoun, singular is not usually followed by a noun, plural, common
Suggestion: Refer to this and hypotheses
The trees’ population have been decrease in lower elevated places
The trees’ populations have been decreased in lower elevated places
Attribute Value Ideal
Score: 24 in 30
Category: Good Excellent
No. of Grammatical Errors: 2 2
No. of Spelling Errors: 0 2
No. of Sentences: 15 12
No. of Words: 272 250
No. of Characters: 1380 1200
No. of Different Words: 137 150
Fourth Root of Number of Words: 4.061 4.2
Average Word Length: 5.074 4.6
Word Length SD: 2.375 2.4
No. of Words greater than 5 chars: 110 80
No. of Words greater than 6 chars: 76 60
No. of Words greater than 7 chars: 35 40
No. of Words greater than 8 chars: 25 20
Use of Passive Voice (%): 0 0
Avg. Sentence Length: 18.133 21.0
Sentence Length SD: 5.976 7.5
Use of Discourse Markers (%): 0.533 0.12
Sentence-Text Coherence: 0.367 0.35
Sentence-Para Coherence: 0.573 0.50
Sentence-Sentence Coherence: 0.118 0.07
Number of Paragraphs: 4 4