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 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 insectis 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 cold winter nights. This frozen root damage may be capable of undermining the health of the whole tree, eventually killing it.
The professor in the lecture disputes the hypotheses of what caused the continuous decrease in number of yellow cedar in northwestern North America carried out in the passage, concluding that none of the factors is adequate to elaborate this phenomenon.
To begin with, the reading material suggests that insects may be attributed to the decline of yellow cedar population by eating the wood. However, the professor rebuts with evidence that healthy trees themselves produce a poisonous substance to defend such beetles, which indicates that those suffered from parasites may have already been damaged somehow, and are possible to die out even without the insects. Hence, first the proposal is negated since it cannot explain why these trees were devastated in the first place.
The next statement in the passage is that bears who feed on the yellow cedar could have weakened them and are responsible for the declination. Whereas the speaker points out that the whole region of northwestern North America, including the mainland and island is suffering from the decrease, yet there is no bear on the islands, which manifests that the yellow cedars are disappearing with or without the bears. Therefore, this factor is of no influence to the population of the trees.
Lastly, the reading passage blames the changes of climate to have led to the decline since the roots will suffer from freezing on winter evenings, which undermines the wholesome of the entire tree. But the lecturer contradicts with this opinion with the fact that more trees are died in the comparatively warmer locations than in the colder spots. Had the climate been the killer, we would expect the opposite. We could only safely conclude that the weather has made the trees more sensitive, but not has killed them in large number. So again, this third point fails to stand.
Transition Words or Phrases used:
but, first, hence, however, if, lastly, may, so, therefore, third, whereas, to begin with, in the first place
Attributes: Values AverageValues Percentages(Values/AverageValues)% => Comments
Performance on Part of Speech:
To be verbs : 14.0 10.4613686534 134% => OK
Auxiliary verbs: 7.0 5.04856512141 139% => OK
Conjunction : 7.0 7.30242825607 96% => OK
Relative clauses : 13.0 12.0772626932 108% => OK
Pronoun: 21.0 22.412803532 94% => OK
Preposition: 47.0 30.3222958057 155% => OK
Nominalization: 7.0 5.01324503311 140% => OK
Performance on vocabulary words:
No of characters: 1543.0 1373.03311258 112% => OK
No of words: 304.0 270.72406181 112% => OK
Chars per words: 5.07565789474 5.08290768461 100% => OK
Fourth root words length: 4.17559525986 4.04702891845 103% => OK
Word Length SD: 2.54825103987 2.5805825403 99% => OK
Unique words: 178.0 145.348785872 122% => OK
Unique words percentage: 0.585526315789 0.540411800872 108% => OK
syllable_count: 478.8 419.366225166 114% => OK
avg_syllables_per_word: 1.6 1.55342163355 103% => OK
A sentence (or a clause, phrase) starts by:
Pronoun: 4.0 3.25607064018 123% => OK
Article: 5.0 8.23620309051 61% => OK
Subordination: 0.0 1.25165562914 0% => More adverbial clause wanted.
Conjunction: 4.0 1.51434878587 264% => Less conjunction wanted as sentence beginning.
Preposition: 1.0 2.5761589404 39% => More preposition wanted as sentence beginning.
Performance on sentences:
How many sentences: 12.0 13.0662251656 92% => OK
Sentence length: 25.0 21.2450331126 118% => OK
Sentence length SD: 76.0202367063 49.2860985944 154% => OK
Chars per sentence: 128.583333333 110.228320801 117% => OK
Words per sentence: 25.3333333333 21.698381199 117% => OK
Discourse Markers: 9.08333333333 7.06452816374 129% => OK
Paragraphs: 4.0 4.09492273731 98% => OK
Language errors: 0.0 4.19205298013 0% => OK
Sentences with positive sentiment : 2.0 4.33554083885 46% => More positive sentences wanted.
Sentences with negative sentiment : 8.0 4.45695364238 179% => OK
Sentences with neutral sentiment: 2.0 4.27373068433 47% => OK
What are sentences with positive/Negative/neutral sentiment?
Coherence and Cohesion:
Essay topic to essay body coherence: 0.261032932175 0.272083759551 96% => OK
Sentence topic coherence: 0.082389140676 0.0996497079465 83% => OK
Sentence topic coherence SD: 0.0332001959507 0.0662205650399 50% => OK
Paragraph topic coherence: 0.147989044464 0.162205337803 91% => OK
Paragraph topic coherence SD: 0.0112830434889 0.0443174109184 25% => Paragraphs are similar to each other. Some content may get duplicated or it is not exactly right on the topic.
Essay readability:
automated_readability_index: 15.2 13.3589403974 114% => OK
flesch_reading_ease: 46.1 53.8541721854 86% => OK
smog_index: 8.8 5.55761589404 158% => OK
flesch_kincaid_grade: 13.0 11.0289183223 118% => OK
coleman_liau_index: 12.48 12.2367328918 102% => OK
dale_chall_readability_score: 9.14 8.42419426049 108% => OK
difficult_words: 82.0 63.6247240618 129% => OK
linsear_write_formula: 19.5 10.7273730684 182% => OK
gunning_fog: 12.0 10.498013245 114% => OK
text_standard: 13.0 11.2008830022 116% => OK
What are above readability scores?
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Rates: 86.6666666667 out of 100
Scores by essay e-grader: 26.0 Out of 30
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Note: the e-grader does NOT examine the meaning of words and ideas. VIP users will receive further evaluations by advanced module of e-grader and human graders.