作者：BRODIE FARQUHAR   翻译：小婧 

狼正在引起一系列生态变化，包括增加河狸的数量，提高白杨等植被的覆盖率。

Wolves are causing a trophic cascade of ecological change, including helping to increase beaver populations and bring back aspen, and vegetation.

在一个带有春天气息的幽静早晨，一响亮的拍打声在黄石湖的遥远溪流上方的空气中回荡。在过去一个世纪中的大部分时间里，黄石公园的音景中很少出现这样的声音，但是如今，这种声音越来越普遍了—（这种声音就是）河狸把自己的尾巴拍打在水面上，以警告其他河狸。（应该是相当于发出警示信号..）

On a quiet spring morning, a resounding "Slap!" reverberates through the air above a remote stream leading to Lake Yellowstone. Over much of the past century, it has been a rarely heard noise in the soundscape that is Yellowstone National Park, but today is growing more common-the sound of a beaver slapping its tail on the water as a warning to other beavers.

负责黄石狼项目的野生生物生物学家道格·史密斯说：“当灰狼在1995年被重新引入黄石生态系统时，公园里只有一个河狸种群的栖息地。

When the grey wolf wasreintroduced into the Greater Yellowstone Ecosystem in 1995, there was only one beaver colony in the park, said Doug Smith, a wildlife biologist in charge of the Yellowstone Wolf Project.

如今，该公园已经是九个河狸种群的家园，此外还会出现更多河狸栖息地。随着狼的再引入，其继续让生物学家感到惊讶——（狼的重新引入）在整个生态系统中直接或间接地产生了连锁反应。

Today, the park is home to nine beaver colonies, with the promise of more to come, as the reintroduction of wolves continues to astonish biologists with a ripple of direct and indirect consequences throughout the ecosystem. A flourishing beaver population is just one of those consequences, said Smith.

重新引进黄石公园的狼 图/Doug Smith

黄石公园中的河狸与麋鹿的故事

A Yellowstone Beaver's Tale of Elk

Smith说：“发生的事情是，狼的存在引发了动植物之间仍在不断发展的级联效应，这需要数十年的研究才能理解。”

What happened, said Smith, is that the presence of wolves triggered a still-unfolding cascade effect among animals and plants-one that will take decades of research to understand.

“这就像把一颗卵石从山坡上踢下去，在条件正好的地方，一颗落下的卵石可能会引发雪崩般的变化。”Smith 沉思。

"It is like kicking a pebble down a mountain slope where conditions were just right that a falling pebble could trigger an avalanche of change," Smith mused.

那么，这种雪崩式的变化是如何对河狸产生影响的呢

So how did this avalanche of change work out for the beaver?

为了回答这个问题，你得回到20世纪30年代，那正是在黄石公园里的狼被杀光的时间。尽管黄石麋鹿仍然被黑熊、灰熊，美洲狮和小土狼所捕食，但狼的消失减轻了麋鹿巨大的不是压力。所带来的结果是：麋鹿的数量剧增。从而发生了两件事：麋鹿把黄石公园的承载能力推到了极限。它们在冬季里很少走动，主要以柳树、白杨和杨木为食。（使得许多柳树、杨树都被啃光了）。这便使河狸陷入困境，因为河狸需要柳树来过冬。

To answer that, you have to go back to the 1930s, when the wolf was killed off in Yellowstone. Even though Yellowstone elkwere still preyed upon by black and grizzly bears, cougars and, to a lesser extent, coyotes, the absence of wolves took a huge amount of predatory pressure off the elk, said Smith. As a result, elk populations did very well-perhaps too well. Two things happened: the elk pushed the limits of Yellowstone's carrying capacity, and they didn't move around much in the winter-browsing heavily on young willow, aspen and cottonwood plants. That was tough for beaver, who need willows to survive in winter.

有更多更健康的柳树矗立在黄石公园

Healthier Willow Stands in Yellowstone

这就造成了一种违反直觉的情况，早在1968年，当时的麋鹿数量只有现在的三分之一，小溪边的柳树也岌岌可危。如今，麋鹿的数量是以前的三倍，柳树也很茂盛。为什么会这样呢?因为来自狼的掠食压力使麋鹿不停地迁移移动，所以它们没有时间再仔细地（强烈地）吃（啃）柳树。

This created a counterintuitive situation. Back in 1968, said Smith, when the elk population was about a third what it is today, the willow stands along streams were in bad shape. Today, with three times as many elk, willow stands are robust. Why? Because the predatory pressure from wolves keeps elk on the move, so they don't have time to intensely browse the willow.

黄石公园的麋鹿 图/Holtzter

事实上，由美国柯林斯堡地质调查局(U.S. Geological Survey)领导的一个研究项目发现，麋鹿密集地啃食柳树，河狸的模拟扦插，会导致柳树生长发育不良。相反，在没有麋鹿啃食的情况下进行模拟河狸切割，会产生翠绿的，健康的柳树。在为期三年的实验中，未被啃食过的植物的柳茎生物量是被啃食过的植物的10倍。仅在两个生长季节后，未被啃食的植物就恢复了84％的预切生物量，而被啃食过的植物仅恢复了6％。PS：生物量：是指某一时刻单位面积内实存生活的有机物质（包括生物体内所存食物的重量）总量

Indeed, a research project headed by the U.S. Geological Survey in Fort Collins found that the combination of intense elk browsing on willows and simulated beaver cuttings produced stunted willow stands. Conversely, simulated beaver cutting without elk browsing produced verdant, healthy stands of willow. In the three-year experiment, willow stem biomass was 10 times greater on unbrowsed plants than on browsed plants. Unbrowsed plants recovered 84 percent of their pre-cut biomass after only two growing seasons, whereas browsed plants recovered only 6 percent.

随着麋鹿在冬天的迁徙，柳树也从激烈的被啃食中恢复了元气，河狸也重新发现了前所未有的丰富的食物来源。

With elk on the move during the winter,willow stands recovered from intense browsing, and beaver rediscovered an abundant food source that hadn't been there earlier.

随着河狸建水坝和池塘蓄水，级联效应（PS：级联效应：是由一个动作影晌系统而导致一系列意外事件发生的效应。例如:在生态系统内,某一种重要物种的死亡,可能触发其它物种的灭绝）仍然存在。河狸修建的水坝对溪流地段的水文有多重影响，它们平衡了径流的季节性流动; 蓄水则用于补充地下水位，为鱼儿提供了阴凉的冷水，而如今健壮的柳林为歌唱的鸟儿们提供了栖息地。

As the beavers spread and built new dams and ponds, the cascade effect continued, said Smith. Beaver dams have multiple effects on stream hydrology. They even out the seasonal pulses of runoff; store water for recharging the water table; and provide cold, shaded water for fish, while the now robust willow stands provide habitat for songbirds.

我们所发现的是生态系统是非常复杂的。除了狼改变了麋鹿的进食习惯外， 黄石公园河狸数量的回升也可能受到1988年黄石公园大火、持续的干旱、温暖干燥的冬天以及其他尚未被发现的因素的影响。

"What we're finding is that ecosystems are incredibly complex," he said. In addition to wolves changing the feeding habits of elk, the rebound of the beaver in Yellowstone may also have been affected by the 1988 Yellowstone fires, the ongoing drought, warmer and drier winters and other factors yet to be discovered, Smith said.

黄石公园中的狼的级联效应

Yellowstone Wolf Trophic Cascade

生物学家们经常面临着一项严峻的任务，即记录当一个物种因局部灭绝甚至灭绝而从生态系统中消失时所发生的连锁反应。在黄石国家公园，生物学家们拥有罕见的，几乎独一无二的机会去记录当一个生态系统再次变得完整时会发生什么 ，当一个关键物种被重新加入生态系统的平衡（生态系统方程）时会发生什么。

Biologists are often faced with the grim task of documenting the cascade effects of what happens when a species is removed from an ecosystem, by local extirpation or even extinction. In Yellowstone, biologists have the rare, almost unique, opportunity to document what happens when an ecosystem becomes whole again, what happens when a key species is added back into the ecosystem equation.

Smith说：“在整个科学文献中，只有五到六个可比较的状况。我们现在所能看到的是一项狂热的科学研究。”

"In the entire scientific literature, there are only five or six comparable circumstances," Smith said. "What we're seeing now is a feeding frenzy of scientific research."

Montana State University生态学教授斯科特·克里尔(Scott Creel)对这项研究十分狂热 。（ps：这里不太会翻译哇..）

Scott Creel, an ecology professor at Montana State University, is hip-deep in that feeding frenzy.

“我一直在加勒廷峡谷做研究”Creel说道“这里有四个流域是麋鹿栖息的地方。”狼来了又走，这使他能够研究麋鹿在狼存在和不存在时的行为。

"My research has been in the Gallatin Canyon," said Creel, where elk inhabit four drainages. Wolves come and go, he said, enabling him to study what elk do in the presence and absence of wolves.

“麋鹿已经被证明具有很强的适应性”Creel说道“当狼群在（麋鹿）身边时，麋鹿会更警觉，会更少觅食（这里的觅食是啃食杨树柳树等植被）

"Elk have proven to be pretty adaptable," Creel said. "When wolves are around, they're more vigilant and do less foraging."

克里尔补充说，当狼在附近的时候，麋鹿会走到茂密的森林里，但是当狼离开的时候，麋鹿会回到草地上。克里尔和其他研究人员仍在研究这对麋鹿的饮食习惯意味着什么，以及这种行为是否会带来相应的代价。

Elk move into heavy timber when wolves are around, Creel added, but return to the grassy, open meadows when wolves go away. Creel and other researchers are still working out what that means in terms of the elk's diet and whether there are costs associated with this behavior.

黄石公园的灰狼在追捕麋鹿 图/Doug Smith

相当令人感到惊讶的是，当狼靠近时麋鹿群的大小会分裂成更小的单位，克里尔原本所期望的，是麋鹿群的大小变得更大是作为一种防御机制。“我认为它们是在试图避免与狼的相遇，”他说，“它们（指麋鹿）变得更加警惕，进入森林，聚集成较小的群体。”

Rather surprisingly, elk herd size breaks up into smaller units when wolves are around, said Creel, who had expected herd size to get bigger as a defense mechanism. "I think they're trying to avoid encounters with wolves," he said, by being more vigilant, moving into the timber and gathering in smaller herd units.

黄石公园的狼是食物的分配者

Yellowstone Wolves are Food Distributors

研究人员还确定（立论）在最近没有严冬的情况下，狼是造成麋鹿死亡的原因。在狼还没被重新引进（黄石公园）之前，深深的积雪是麋鹿是否会死亡的主要决定因素。

Researchers have also determined that wolves, in the recent absence of hard winters, are now the primary reason for elk mortality. Before wolf reintroduction, deep snows were the main determinant of whether an elk was going to die.

加州大学伯克利分校的研究人员还确定（立论），雪的减少和狼的增多使大大小小的食腐动物受益——从乌鸦到灰熊。

Researchers from the University of California at Berkeley determined that the combination of less snow and more wolves has benefited scavengers both big and small, from ravens to grizzly bears.

克里斯·威尔默斯(Chris Wilmers)在《科学公共图书馆生物学》(Public Library of Science Biology)在线期刊上说：“在还未重新引入狼前，麋鹿腐肉的供应处于一时过多，一时过少的状态，这样便使得严冬下的生存条件变困难。而引入狼后平衡了麋鹿腐肉的供应，使得在严冬到早春这段时间，更有利于以腐肉为食物的动物们的生存（或者可以理解为：之前有狼和严冬的时候，分布有繁荣和衰败的周期性，而现在冬天和早春的时候分布的更均匀）”他补充说，曾经以被冬天杀死的麋鹿为食的食腐动物，现在则以被狼杀死的麋鹿为食。这对乌鸦、老鹰、喜鹊、郊狼和熊(灰熊和黑熊)，特别是当熊从冬眠中的饥饿中醒来的时候都有好处，

Instead of a boom and bust cycle of elk carrion availability-as existed before wolves and when winters were harder-there's now a more equitable distribution of carrion throughout winter and early spring, said Chris Wilmers in the on-line journal Public Library of Science Biology. He added that scavengers that once relied on winter-killed elk for food now depend on wolf-killed elk. That benefits ravens, eagles, magpies, coyotes and bears (grizzly and black), especially as the bears emerge hungry from hibernation.

“我把它称为大众食物”美国鱼类和野生动物服务机构的狼恢复协调员Ed Bangs说道。他说他真的对与狼杀事件有关的庞大生命网络感到惊讶。“甲虫，金刚狼，猞猁还有更多的动物，原来印度乌鸦追狼的传说是真的——它们追狼是因为狼意味着食物。”他补充道。

"I call it food for the masses," said Ed Bangs, wolf recovery coordinator for the U.S. Fish and Wildlife Service. He said he was genuinely surprised by the vast web of life that is linked to wolf kills. "Beetles, wolverine, lynx and more," he said. "It turns out that the Indian legends of ravens following wolves are true-they do follow them because wolves mean food."

个人观点：生物世界多姿多彩，生态系统要比我们设想的复杂得多，即使黄石公园重新引入狼给当地生态系统带来了不少积极影响，但黄石公园还有一部分区域的生态并没有恢复，仍然和没有灰狼的时候一样河水急流、荒草丛生、生物多样性单调。在还未引入狼之前所带来但损失不是一时半会可以补救的了的，（更多详细的内容可观阅《科学世界》2018.10 方舟子的文章《黄石公园与狼的浪漫史》）生态系统一旦被破坏，恢复起来也要比我们设想的困难得多，甚至是不可完全恢复的了。我们需要做的，是尽量保护生态系统，而不是幻想着在破坏了之后再用简单的办法恢复它。

Plus：我之所以选择翻译这篇文章，是因为偶然间看到了斜前桌的新买的英语“5 3”中有一篇关于黄石公园重新引入狼的阅读理解，我碰巧看过官网的文章，因此心情澎湃之下翻译了此文⊙∀⊙！

附上那篇高考阅读理解，供各位参考～🔽

After years of heated debate, gray wolves were reintroduced to Yellowstone National Park. Fourteen wolves were caught in Canada and transported to the park. By last year, the Yellowstone wolf population had grown to more than 170 wolves.

Gray wolves once were seen here and there in the Yellowstone area and much of the continental United States, but they were gradually displaced by human development. By the 1920s, wolves had practically disappeared from the Yellowstone area. They went farther north into the deep forests of Canada, where there were fewer humans around.

The disappearance of the wolves had many unexpected results. Deer and elk populations — major food sources (来源) for the wolf – grew rapidly. These animals consumed large amounts of vegetation (植被), which reduced plant diversity in the park. In the absence of wolves, coyote populations also grew quickly. The coyotes killed a large percentage of the park’ s red foxes, and completely drove away the park’ s beavers.

As early as 1966,biologists asked the government to consider reintroducing wolves to Yellowstone Park.They hoped that wolves would be able to control the elk and coyote problems.Many farmers opposed the plan because they feared that wolves would kill their farm animals or pets.

    The government spent nearly 30 years coming up with a plan to reintroduce the wolvers. The U.S.Fish and Wildlife Service carefully monitors and manages the wolf packs in Yellowstone.Today,the debate continues over how well the gray wolf is fitting in at Yellowstone.Elk,deer,and coyote populations are down,while beavers and red fores have made a comeback.The Yellowstone wolf project has been a valuable experiment to help biologists decide whether to reintroduce wolves to other parts of the country as well.

1.What is the text mainly about?

A.Wildlife research in the United States.

B.Plant diversity in the Yellowstone area.

C.The conflict between farmers and gray wolves.

D.The reintroduction of wolves to Yellowstone Park.

2.What does the underlined word “displaced” in paragraph 2 mean?

A.Tested.  B.Separated.  C.Forced out.  D.Tracked down.

3.What did the disappearance of gray wolves bring about？

A.Damage to local ecology.     B.A decline in the park’s income.

C.Preservation of vegetation.    D.An increase in the variety of animals.

4.What is the author’s attitude towards the Yellowstone wolf project？

A.Doubtful.       B.Positive.      C.Disapproving.      D.Uncaring.

本文章翻译版权归翻译者小婧所有，转载请完整保留作者及翻译者的信息

原文出处：https://www.yellowstonepark.com/things-to-do/wolf-reintroduction-changes-ecosystem