樹(shù)木死亡和氣候
【時(shí)事聚焦】 近一個(gè)世紀(jì)，世界上森林覆蓋面積大幅度銳減，除了人為因素的大量砍伐，也有相當(dāng)數(shù)量的樹(shù)木由于自然氣候死亡。自然氣候的改變帶來(lái)的炎熱和干旱導(dǎo)致了世界上越來(lái)越多的樹(shù)木奄奄一息。下面我們就來(lái)看一則建立在幾十篇科學(xué)文獻(xiàn)基礎(chǔ)上，有關(guān)此話題的最新報(bào)道。
TreeDeaths Linked To Climate Change
Hot and dry conditions triggeredby climate change are killing the world's trees, according to a new reportwhich examines dozens of scientific articles on the subject.
Stanford Universitygraduate student William Anderegg has seen this forest die-off firsthand.
His doctoral thesisdocuments the impact of drought on trembling aspen, the most common tree inNorth America.
“These are completehillsides of trembling aspens that are dying off," Anderegg says."And when the main tree in a forest goes, you tend to see a lot of theother species, especially the grasses and the wild flowers, tend to disappearas well. But you lose a lot of those species from those forests.”
Changing ecology
With colleagues fromStanford and North Arizona State University, Anderegg co-authored the newreport which presents a picture of accelerating worldwide tree deaths thatappear to be linked to changes in the global climate.
Anderegg says thesechanges, triggered by rising levels of heat-trapping gases in the atmosphere,are stressing the world’s forests.
“One of the ways thatwe expect climate change to increasingly play out in forests is through thesewidespread tree mortality events where you stress the trees enough that youessentially push a whole region of them off the edge and in fact what happensafterwards, after a forest dies from drought is every bit as important and insome sense matters more to humans who rely on forests.”
Trees provide a rangeof ecological services. They hold soil in place, help purify water and shelterspecies. They are valued for timber and tourism. When trees die, the ecologyand hydrology of a forest change, which in turn promotes insect infestation andfire.
This can result inlong-term shifts in the area’s dominant species and may even trigger atransition to a different ecosystem, such as grass land.
Devastating consequence
Anderegg says themost devastating consequence may be that the changing forests, in turn, willstart affecting the global climate.
“Because forests do alot to stabilize the climate and to store carbon and when they start to dieoff, you can actually have forest die-off accelerate climate change," hesays. "You get into a vicious cycle.”
This is especiallytroubling for Anderegg because trees, which cover 30 percent of the earth’ssurface, absorb 25 percent of the climate-changing gases emitted into theatmosphere from cars, buildings and factories.
Forest monitoring
While scientists aregetting better at tracking the effects of climate change on forests, data isstill sparse. Anderegg says his study urges governments and specialists frommany disciplines to support wide-scale forest monitoring.
“It is not justecologists, but we also need people working with satellites. We need people ingovernment agencies. We need people on the ground to do this as well. It’sunfortunately not something that just the scientific research community canpull off on their own.”
Anderegg, whoseresearch is published in Nature Climate Change, says a better understanding ofhow climate change is killing off the world’s forests can help shape betterforest management, business decisions and policies.【熱點(diǎn)話題】 根據(jù)以上的這則研究報(bào)道，我們發(fā)現(xiàn)樹(shù)木死亡的話題和雅思閱讀考試有十分緊密的聯(lián)系，雅思閱讀話題中有很多都涉及到環(huán)保，生態(tài)，這在2012年1月-9月的考試中可見(jiàn)一斑。平時(shí)對(duì)這類話題的背景知識(shí)累積有助于考生更好地理解新文章。因?yàn)槲鼰釟怏w在大氣層中的不斷增加，所以不僅是森林里的樹(shù)木，野花和草類也逐漸消失。這樣的后果會(huì)造成該地區(qū)生態(tài)系統(tǒng)的改變，轉(zhuǎn)而再次影響全球氣候。
【難句詞匯】 雅思考生的閱讀難點(diǎn)之一就是對(duì)詞匯量和句型的掌握程度不同，如果學(xué)生的詞匯量不足，那么文章將看不懂，我們從上文中就可以學(xué)到很多的句型和詞匯。
› Hot and dry conditions triggered by climate changeare killing the world's trees, according to a new report which examines dozensof scientific articles on the subject.
定語(yǔ)后置修飾(過(guò)去分詞短語(yǔ)作后置定語(yǔ))
l trigger v. 導(dǎo)致，引發(fā)
l dozens of 幾十個(gè)
› These are complete hillsides of trembling aspensthat are dying off, the most common tree in North America.
定語(yǔ)從句和同位語(yǔ)
l trembling adj. 顫抖的
l aspen n. 白楊
l die off 死亡，消失
› And when the main tree in a forest goes, you tendto see a lot of the other species, especially the grasses and the wild flowers,tend to disappear as well.
條件狀語(yǔ)從句，插入語(yǔ)
l species n. 種類
l wild adj. 野生的
› One of the ways that we expect climate change toincreasingly play out in forests is through these widespread tree mortalityevents where you stress the trees enough that you essentially push a wholeregion of them off the edge and in fact what happens afterwards, after a forestdies from drought is every bit as important and in some sense matters more tohumans who rely on forests.
定語(yǔ)從句，地點(diǎn)狀語(yǔ)從句，主語(yǔ)從句
l mortality n. 死亡
l drought n. 干旱
l in some sense 在某種意義上
l edge n. 邊緣
› When trees die, the ecology and hydrology of aforest change, which in turn promotes insect infestation and fire.
時(shí)間狀語(yǔ)從句、非限制型定語(yǔ)從句
l ecology n. 生態(tài)
l hydrology n. 水文學(xué)
l infestation n. (害蟲)出沒(méi)，橫行
› Because forests do a lot to stabilize the climateand to store carbon and when they start to die off, you can actually haveforest die-off accelerate climate change," he says. "You get into avicious cycle.
原因狀語(yǔ)從句，時(shí)間狀語(yǔ)從句
l stabilize v. 使…穩(wěn)定
l accelerate v. 增加，加速
l vicious adj. 兇猛的，惡劣的
從以上這些內(nèi)容中我們學(xué)到了很多的表達(dá)方式和句型，這樣一來(lái)對(duì)于雅思閱讀的理解力和速度的提高有很大的幫助。從文章結(jié)構(gòu)上來(lái)看，本文是很明顯的現(xiàn)象—解釋原因—后果—預(yù)測(cè)——建議的行文模式。這和很多劍橋系列里的文章相似。文章中同時(shí)也涉及了許多生態(tài)，環(huán)保類的雅思高頻詞，比如 stabilize,infest, mortality等等。
分析發(fā)現(xiàn)，在劍橋雅思真題中也有相關(guān)類型的文章供考生閱讀理解和訓(xùn)練：劍四Rainforest; 劍七Deforestation; 劍七The Little Ice Age, 以上三篇文章都是當(dāng)下熱點(diǎn)的環(huán)保類文章，考生可以精讀加考題訓(xùn)練。
【真題預(yù)測(cè)】 根據(jù)剛才關(guān)于樹(shù)木死亡和氣候的原版文章，我們來(lái)練習(xí)一下雅思閱讀的?？碱}型之——是非無(wú)判斷題：
Do the following statements agree with the views of the writer in thispassage?
TRUE / FALSE / NOT GIVEN
1. If a kind of speciesdie off, the ecology of this region is likely changed also.
2. Forests only serveas the role of storing carbon.
3. The government isnow carrying out specific programs to address this deteriorating phenomenon.