长期干旱影响加州的红杉

AS IT IS 2015-10-04 Drought Affecting California’s Sequoias 长期干旱影响加州的红杉

California continues to suffer under a historic drought. The state has received very little rainfallover the past four years.

California is famous for its huge sequoia¹ trees. They are among the largest and oldest living thingson Earth. But scientists say the trees are suffering because of the lack of water.

Now the National Park Service is studying how the drought has affected² the sequoias and what canbe done to help them survive.

Anthony Ambrose is a tree biologist with the University of California, Berkeley. One recent day, heslowly climbed up a giant sequoia in California's Sierra Nevada Mountains. The Sierra Nevada rangeis the only place on earth where sequoias live.

"It's an amazing experience to be able to climb up into these things and know that it's beengrowing in this same spot for you know a thousand years or more."

Sequoias can grow to a height of over 90 meters tall. The bottom of the tree can be up to 15meters wide. Some trees are more than 3,000 years old.

The Sierra Nevada range once had plenty of water because of mountain streams. But less water isavailable now because of the drought. Each sequoia needs more than 3,000 liters of water a day. The trees are now getting much less. Some of them are showing signs of thirst, says AnthonyAmbrose.

"We've observed some unusual and abnormal levels of foliage³ die-back, which haven't beenobserved in the park before."

Researchers are using scientific equipment in tree canopies⁴ to help measure air temperature andhumidity levels. They also are studying sequoia seedlings⁵, information from individual trees andimages collected by aircraft to measure the seriousness of the danger.

One possible solution would be to cut down less important tree species because other plantscompete with the sequoias for water. Koren Nydick of the National Park Service is one of thescientific investigators⁶.

"They'll have more water than they would have in a denser⁷ forest, more nutrients⁸ and light andtherefore be more resistant⁹ and resilient to these hot droughts they're faced with in the future."

Scientists say that over thousands of years, sequoias have survived many droughts, forest fires,insect infestations¹⁰ and other disasters. Scientists say the sequoias will probably survive thisdrought, unlike many other California trees.

Words in This Story

drought – n. a long time during which there is very little or no rain

thirst – n. a very great need for something to drink

die-back - n. a condition in which a plat begins, owing to disease or an unfavorable environment

canopy¹¹ - n. something that hangs or spreads out over an area

humidity – n. wetness in the air

1 sequoia   

n.红杉

参考例句：

• The sequoia national forest is at the southern end of the sierra nevada range.红杉国家公园位于内华达山脉南端尽头处。
• The photo shows the enormous general Sherman tree in California's sequoia national park.照片显示的是加利福尼亚州红杉国家公园内巨大的谢尔曼将军树。

2 affected   

adj.不自然的，假装的

参考例句：

• She showed an affected interest in our subject.她假装对我们的课题感到兴趣。
• His manners are affected.他的态度不自然。

3 foliage   

n.叶子，树叶，簇叶

参考例句：

• The path was completely covered by the dense foliage.小路被树叶厚厚地盖了一层。
• Dark foliage clothes the hills.浓密的树叶覆盖着群山。

4 canopies   

（宝座或床等上面的）华盖( canopy的名词复数 )； （飞行器上的）座舱罩； 任何悬于上空的覆盖物； 森林中天棚似的树荫

参考例句：

• Golf carts with bright canvas canopies wandered the raingreen fairways. 一场雨后显得愈加葱绿的高尔夫球场草地上，散放着一些带有色彩缤纷的帆布华盖的高尔夫小车。
• Rock permitted seven canopies, cornices floors, decorative glass, Ambilight, momentum magnificent, magnificent. 七檐佛殿背倚山岩，楼层飞檐翘角，殿顶琉璃装饰，流光溢彩，气势恢宏，蔚为壮观。

5 seedlings   

n.刚出芽的幼苗( seedling的名词复数 )

参考例句：

• Ninety-five per cent of the new seedlings have survived. 新栽的树苗95%都已成活。 来自《现代汉英综合大词典》
• In such wet weather we must prevent the seedlings from rotting. 这样的阴雨天要防止烂秧。 来自《现代汉英综合大词典》

6 investigators   

n.调查者，审查者( investigator的名词复数 )

参考例句：

• This memo could be the smoking gun that investigators have been looking for. 这份备忘录可能是调查人员一直在寻找的证据。
• The team consisted of six investigators and two secretaries. 这个团队由六个调查人员和两个秘书组成。 来自《简明英汉词典》

7 denser   

adj. 不易看透的, 密集的, 浓厚的, 愚钝的

参考例句：

• The denser population necessitates closer consolidation both for internal and external action. 住得日益稠密的居民，对内和对外都不得不更紧密地团结起来。 来自英汉非文学 - 家庭、私有制和国家的起源
• As Tito entered the neighbourhood of San Martino, he found the throng rather denser. 蒂托走近圣马丁教堂附近一带时，发现人群相当密集。

8 nutrients   

n.（食品或化学品）营养物，营养品( nutrient的名词复数 )

参考例句：

• a lack of essential nutrients 基本营养的缺乏
• Nutrients are absorbed into the bloodstream. 营养素被吸收进血液。 来自《简明英汉词典》

9 resistant   

adj.(to)抵抗的，有抵抗力的

参考例句：

• Many pests are resistant to the insecticide.许多害虫对这种杀虫剂有抵抗力。
• They imposed their government by force on the resistant population.他们以武力把自己的统治强加在持反抗态度的人民头上。

10 infestations   

n.（害虫、盗贼等）群袭，出没，横行( infestation的名词复数 )

参考例句：

• The arrival of warm weather raises the specter of disease and increased rat infestations caused by rotting garbage. 天气转暖使人们担心垃圾腐烂会引起疾病传播和鼠群猖獗。 来自《简明英汉词典》
• Piperazine citrate is the drug of choice in the treatment of Ascaris infestations. 枸橼酸哌嗪治疗蛔虫感染是最好的药物。 来自辞典例句

11 canopy   

n.天篷，遮篷

参考例句：

• The trees formed a leafy canopy above their heads.树木在他们头顶上空形成了一个枝叶茂盛的遮篷。
• They lay down under a canopy of stars.他们躺在繁星点点的天幕下。