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Now listen to part of a lecture on the topic you just read about.
現(xiàn)在來聽一段關(guān)于你剛剛聽到的話題的演講。
Unfortunately, we still don't know what is killing the yellow cedar.
很遺憾，我們?nèi)匀徊恢朗鞘裁丛诙髿ⅫS杉。
None of the explanations discussed in the reading is adequate.
閱讀中討論的解釋沒有一個(gè)是適當(dāng)?shù)摹?/div>
First, the cedar bark beetle.
首先，杉樹樹皮甲蟲。
Well, the problem with this explanation is these healthy yellow cedars are generally much more resistant to insect infestation than the other tree species.
嗯，這個(gè)解釋的問題在于這些健康的黃杉一般來說比其他樹種對害蟲入侵更有抵抗力。
For example, the bark and leaves of the yellow cedar are saturated with powerful chemicals that are poisonous to insects.
比如，黃杉的樹皮和葉子上飽和著對于昆蟲來說有毒的強(qiáng)力化學(xué)物質(zhì)。
So healthy cedars are unlikely to suffer from insect damage.
所以健康的黃衫不會遭受昆蟲破壞。
So how can we explain those dead cedars that were infested with beetles?
那么，我們該如何解釋那些寄居著甲蟲的死杉樹呢？
In those cases, the beetles attack trees that were already damaged or sick, and would have probably died anyway.
在那些情況里，甲蟲侵襲的是已經(jīng)受損或者患病，也許不論如何都會死掉的樹。
So the beatles are not the fundamental cause responsible for the decline of the yellow cedars.
所以，甲蟲不是導(dǎo)致黃杉減少的根本原因。
Second, although bears damage some trees, they are not the cause of the overall population decline.
第二，雖然熊破壞了一些樹木，它們不是總體數(shù)量減少的原因。
Yellow cedar population has been declining all across of the Northwestern coast of North America, both on the mainland and on islands just off the coast.
在北美西北部整個(gè)海岸線上的黃杉數(shù)量都在下降，不管是在大陸還是在離岸的島嶼上。
There are no bears on the islands, yet the islands cedars are still in decline.
那些島嶼上沒有熊，而黃杉的數(shù)量依然在減少。
Since the decline occurs with and without bears, the bears cannot be responsible.
因?yàn)椋〝?shù)量）減少有沒有熊都在發(fā)生，所以熊不會是其原因。
And finally, the theory about the roots suffering from frost damage.
最后，關(guān)于樹根遭受霜凍害的假說。
Well, the reading passage forgot to take one fact into account.
嗯，閱讀文章忘記了考慮一個(gè)事實(shí)。
Many more trees are dying at lower elevations where it is warm than at higher elevations where it is cold.
溫暖的低海拔處比寒冷的高海拔處正在死去的樹更多。
If freezing damage were responsible for the decline, we would expect to see more trees dying in the cold weather of high elevations.
如果凍害是（數(shù)量）減少的原因，我們將會看到在寒冷的高海拔地區(qū)更多的樹死去。
Instead, more trees are dying in the relative warmth over the lower elevations.
反而，在相對溫暖的低海拔處更多的樹正在死去。
So, although the climate change may have made the cedar roots more sensitive than they used to be, this isn't what is killing them.
所以，盡管氣候的變化可能已經(jīng)使杉樹的樹根比以前更加敏感，但是這不是扼殺它們的事情。
