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2020.12.17 How the Wolves Change the Forest
Gray wolves in Minnesota. Credit: Getty Images
This is 60-second science, I'm Jason Goldman.
這是60秒的科學節目 我是傑森-戈德曼
GABLE: "We literally get down on our hands and knees and start slowly sifting through the leaf litter, looking through bits of hair or a little chunk of bone…
"我們從字面上看，我們的手和膝蓋，開始慢慢地篩選樹葉垃圾，通過頭髮的碎片或一小塊骨頭來尋找... ...
Tom Gable is tracking a predator. In fact, he’s tracking a whole pack of them.
湯姆・蓋博正在追蹤一隻掠食者 事實上，他正在追蹤一整群的掠食者。
GABLE: It's very much like a crime scene investigation….
這其實更像是一個犯罪現場調查。
[Sounds of Voyageurs wolves]
Since 2015, the University of Minnesota conservation biologist has used GPS collars to track 30 wolves inside Voyageurs National Park.
自2015年以來，明尼蘇達大學的保護生物學家使用GPS項圈追蹤了沃伊格國家公園內的30隻狼。
Those collars led Gable and his team to kill sites.
這些項圈將Gable和他的團隊引向了殺戮地點。
And there, amid the leaf litter, were bloodied bits of fur and bone … clues about how wolves alter the ecosystems they live, and hunt, and kill in.
在那裡，在樹葉堆中，有帶血的毛皮和骨頭... ...關於狼是如何改變它們生活、狩獵和殺戮的生態系統的線索。
The long-term study is, in a way, a quest to broaden a science story that goes back 25 years.
這項長期研究在某種程度上是為了擴大25年前的科學故事的範圍。
For wildlife ecologists, the story of the reintroduction of wolves to the Greater Yellowstone Ecosystem on January 12, 1995, has become canonical.
對於野生動物生態學家來說，1995年1月12日狼群重新引入大黃石生態系統的故事已經成為典範。
The story goes something like this: as the elk grew to fear the wolves, they changed where and how they foraged.
故事是這樣的：隨著麋鹿越來越害怕狼，它們改變了覓食的地點和方式。
That gave willows, cottonwoods, and aspens a better chance to grow near streams.
這給了柳樹、木棉樹和白楊樹一個更好的機會在溪流附近生長。
It also meant more river-side berries for foraging grizzly bears.
這也意味著有更多的河邊漿果供灰熊覓食。
And it led to alterations in the flow of those streams, sending water in new directions.
這也導致了溪流的流向發生了變化 把水送向新的方向
Wolves outcompete coyotes for access to prey, so coyotes populations plummeted.
狼比土狼更容易獲得獵物 所以土狼的數量急劇下降。
Which led to a rise in fox, rabbit, and ground-nesting bird numbers.
這導致了狐狸，兔子，和地面巢鳥數量的上升。
And so on.
以此類推。
Ecologists call this row of biological dominoes a trophic cascade.
生態學家稱這一排生物多米諾骨牌為營養級聯。
GABLE: "Regardless of your inclination, it's hard not to be like, wow this is amazing. If that is true, it's really incredible."
GABLE："不管你的傾向如何，你很難不喜歡，哇，這太神奇了。"如果這是真的，那真是太不可思議了"
New findings cast some doubt on the idea that wolves primarily regulate the Greater Yellowstone Ecosystem through fear and intimidation.
新的發現對狼群主要通過恐懼和恐嚇來調節大黃石公園生態系統的觀點產生了一些懷疑。
And regardless of the situation there, very little research has been conducted on this question in ecosystems that don't resemble the mountains and grasslands of Yellowstone.
而不管那裡的情況如何，在與黃石公園的山地和草原不相類似的生態系統中，對這個問題的研究很少。
Which brings us back to the boreal forests of northern Minnesota, and the ground that Tom Gable and his team have been crawling over the last few years.
這就把我們帶回了明尼蘇達州北部的北方森林，也是湯姆-蓋博和他的團隊在過去幾年裡一直在爬行的地方。
During the winter, wolves work together to kill large prey like deer.
在冬季，狼群一起合作，殺死像鹿這樣的大型獵物。
But Gable found that in warmer, ice-free months, wolves focus on smaller prey, like newborn deer fawns – and especially beavers.
但蓋博發現，在溫暖無冰的月份裡，狼群會把注意力放在較小的獵物上，比如剛出生的鹿崽--尤其是海狸。
And that’s where things get really interesting for the ecosystem.
這就是生態系統的有趣之處。
GABLE: "Wolves, by preying on dispersing beavers, alter where wetlands are created.
"狼通過捕食分散的海狸 改變了溼地的形成地點
If a young beaver gets killed after leaving home, it will never have a chance to build a new dam.
如果一隻年輕的海狸在離家後被殺 它將永遠沒有機會建造新的水壩。
Even if it had started construction before becoming a wolf's lunch, the dam will remain unfinished and fall into disrepair.
即使它在成為狼的午餐之前就開始建造，大壩也會因未完成而失修。
Beavers are ecosystem engineers. When a wolf kills one, it can have a big impact.
河狸是生態系統的工程師。當狼殺死一隻河狸時，會產生很大的影響。
GABLE: "Because they prevent beavers from converting a forest into a wetland. In that regard, wolves are connected to all the ecological processes that are associated with wetlands and beaver ponds."
"因為它們能阻止海狸將森林變成溼地。在這方面，狼與所有與溼地和海狸池塘相關的生態過程都有聯繫。"
Ecologists have long assumed the predators can influence their ecosystems in two main ways.
生態學家長期以來一直認為，掠食者可以通過兩種主要方式影響其生態系統。
One is through fear and intimidation, like in the Yellowstone story. The second is through direct killing.
一種是通過恐懼和恐嚇，就像黃石公園的故事。二是通過直接殺戮。
The Voyageurs wolves offer up a third possibility.
旅行者狼群提供了第三種可能。
The park and the forests surrounding it have more than 7000 beaver ponds. Gable estimates that wolves have a direct impact each year on around 88 of them.
公園和周圍的森林裡有超過7000個海狸池塘。蓋博估計，狼每年對其中的88個左右產生直接影響。
That’s a mere one and a quarter percent affected.
這僅僅是受影響的百分之一和四分之一。
So it's hard to argue that wolves are responsible for re-shaping the ecosystem in the broadest sense.
所以，很難說狼要為重塑最廣義的生態系統負責。
But it's equally hard to deny that they help to maintain a diversity of habitats across the landscape.
但同樣也很難否認，它們有助於維持整個景觀中棲息地的多樣性。
GABLE: "But I don't really think that estimate is a key finding, so to speak. Because I think the real goal, the real point of our paper was simply to flesh out this mechanism of how wolves do this."
"但我真的不認為這個估計是一個關鍵的發現，可以這麼說。因為我認為，我們論文的真正目標、真正意義只是為了具體化狼群如何做到這一點的這個機制。"
The study was published in the November 13 issue of the journal Science Advances.
這項研究發表在11月13日的《科學進展》雜誌上。
GABLE: "This is something worth studying, and this is likely happening in a variety of ecosystems."
"這是值得研究的事情，這很可能發生在各種生態系統中。"
[Sounds of Voyageurs wolves]
—Jason G. Goldman
(The above text is a transcript of this podcast)
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