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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 | |
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2 affected | |
adj.不自然的,假装的 | |
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3 foliage | |
n.叶子,树叶,簇叶 | |
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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 | |
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5 seedlings | |
n.刚出芽的幼苗( seedling的名词复数 ) | |
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6 investigators | |
n.调查者,审查者( investigator的名词复数 ) | |
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7 denser | |
adj. 不易看透的, 密集的, 浓厚的, 愚钝的 | |
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8 nutrients | |
n.(食品或化学品)营养物,营养品( nutrient的名词复数 ) | |
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9 resistant | |
adj.(to)抵抗的,有抵抗力的 | |
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10 infestations | |
n.(害虫、盗贼等)群袭,出没,横行( infestation的名词复数 ) | |
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11 canopy | |
n.天篷,遮篷 | |
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