Drought And Heat Threaten Sequoias
乾旱與高溫威脅紅杉生存
By Jim Robbins

SEQUOIA NATIONAL PARK, California – High in the Sierras, biologists are struggling to find ways to protect some of the world’s oldest and most storied trees from drought, forest fires and climate change.
生物學家正在加州內華達山脈高處努力找出辦法，以保護一些舉世最古老、最傳奇的巨樹不受乾旱、森林火災與氣候變遷殘害。

The trees are the giant sequoias, some of them 2,000 to 3,000 years old, and they are just one of several ancient Western species, including redwoods and bristlecone pines, that face a daunting future.
這些樹木是巨型紅杉（giant sequoias），部分樹齡已達二、三千年，同樣面臨艱險未來的西方古老樹種還包括另一種紅杉（redwoods，編按：生長在海拔較低處）與芒松。

Although the sequoias are not at immediate risk, scientists say they were not built to withstand decades of dry and warming weather. Their seedlings and saplings are susceptible to fires, which are likely to increase, especially at higher elevations. And the lack of melting snow may keep the seedlings from developing a robust root system.
科學家表示，巨型紅杉雖未面臨立即威脅，卻無法承受數十年的乾旱與不斷暖化的氣候。它們的苗與幼樹易受森林火災影響，而森林火災很可能會增多，尤其是在海拔較高地區。缺少融雪可能使苗木根系難以茁壯。

“If there’s long-term drought, within 25 years, we could see seedlings in trouble,” said Nathan Stephenson, an ecologist with the United States Geological Survey. “In 50 years, the whole population could be in trouble.” Within a century, most of the big trees could be gone, he said.
美國地質調查所生態學家史迪文森說：「如果出現長期乾旱，25年內苗木可能就會面臨麻煩。50年內整個樹群可能大難臨頭。」他說，100年內多數巨樹可能消失。

Sequoias are found in only one place on earth: the Sierra Nevada Mountains in California. There are 65 to 70 groves, most in a narrow 100-kilometer band on the west side of the range at 1,500 to 2,500 meters. They include one tree here called the General Sherman, the world’s largest by volume. Preservation efforts are hampered by the fact that so little is known about big trees, from their root systems to how they die.
全球巨型紅杉只見於一處：加州的內華達山脈。它們約有65到70群，大多位於山脈西側100公里狹長帶狀範圍內，海拔1500到2500公尺的山區。其中的雪曼將軍樹是舉世體積最大的樹。保護工作受阻於對巨樹所知甚少，從根系以至如何死亡。

As the climate changes, so do conditions in which sequoias and other big trees grow. The coastal redwoods of California, for example, are fog drinkers, taking as much as 40 percent of their water in through their needles. In the past half-century, the number of days in which the trees are shrouded by fog has declined by 30 percent. In some places, that appears, to be contributing to growth: With less fog cover there is more light, said Todd E. Dawson, a biologist at the University of California, Berkeley.
隨著氣候不斷變遷，巨型紅杉與其他巨樹成長的條件也不斷改變。以加州沿海地區的紅杉為例，它們會吸收霧氣，透過針葉吸取所需水分的40%。過去半世紀，霧氣籠罩這些樹木的天數累計減少30%。在部分地區，這似乎有助於成長。柏克萊加州大學生物學家陶森表示，如果霧氣籠罩的時間減少，陽光照射相對增加。

“We might start irrigating the sequoias,” Dr. Stephenson said, “or we might build a giant fuel break around the giant sequoias, so if a fire came toward the grove, we could defend it. These things are getting hard discussion.”
史迪文森說：「我們可能開始灌溉紅杉，也可能在巨型紅杉的周圍建造巨大的燃料阻隔體，在火舌逼近時用來保護巨樹群。這些問題已經開始受到嚴肅討論。」

Sequoias are resilient. They have no disease or serious insect enemies, and their spongy bark, 20 centimeters thick, is highly resistant to fires. One can lose 95 percent of its crown in a fire and recover.
紅杉相當強韌。它們沒有疾病或嚴重的昆蟲敵人，厚達20公分的吸水性樹皮具有很好的抗火特性。一顆紅杉即使在一次森林火災中失去95%的樹冠，仍然可以恢復原狀。

A novel program by Sierra Pacific Industries, a lumber producer and the largest landowner in California, has gathered cones from old-growth sequoia groves. In 2012, foresters started to plant seeds in 16 locations with different soil types, elevations and precipitation levels. Some 130,000 seedlings, are now growing from the ancient seeds. The company program is aiming to grow 1.4 million, even though sequoias have little timber value.
生產木材的太平洋山脈產業公司是加州最大的地主，該公司在進行一項新奇的計畫，蒐集已達最後生長或穩定生長時期的巨型紅杉群的毬果。2012年，森林管理員開始在16個土質、海拔與降雨量各不相同的地點埋下種子，如今約有13萬株苗木長自古老的種子。雖然紅杉木料價值極低，這項計畫卻定下了目標，要種植140萬株苗木。

“The goal is to conserve the genetic diversity of the native groves” should the old trees die, the program’s coordinator, Glenn Lunak, said.
計畫協調人魯納克說：「目標是，一旦老樹死亡，還能保住原始樹群的基因多樣性。」

A 2012 study in the journal Science found that 100- to 300-year-old trees were dying at high rates around the world, in part because of hotter and drier weather.
根據一項2012年透過「科學」期刊發表的研究報告，全球各地樹齡100到300年的樹木死亡率偏高，氣候變得更熱更乾是原因之一。

“It’s a very, very disturbing trend,” said an author of the paper, Bill Laurance, an environmental scientist at James Cook University in Australia. “We are talking about the loss of the biggest living organisms on the planet, of organisms that play a key role in regulating and enriching our world.
報告作者之一，研究澳洲詹姆斯．庫克大學的環境科學家勞倫斯說：「這是令人非常、非常困擾的趨勢。這裡說的是全世界失去最大生物的事實。這些生物在調節並豐富這個世界上，扮演著關鍵角色。」

“A world where a child can’t stare up in wonder at a giant cathedral-like crown is a very real possibility.”
「孩子們不再能仰望大如教堂的巨大樹冠並嘆為觀止的未來，很可能會出現。」

原文參照：
http://www.nytimes.com/2014/08/12/science/tall-ancient-and-under-pressure.html

Video：David Milarch wants to stop global warming by climbing and cloning the world’s largest trees.
http://nyti.ms/1925dxp

2014-08-26聯合報/G5版/UNITEDDAILYNEWS 陳世欽譯 原文參見紐時週報十版左