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科学美国人60秒 SSS How Herbivore Herds Might Help Permafrost

时间:2020-05-06 08:52:07

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(单词翻译)

Introducing herds1 of large herbivores in the Arctic would disturb surface snow, allowing cold air to reach the ground and keep the permafrost frosty.

Full Transcript2 

The Arctic’s permafrost is melting—and fast. That’s bad news, because these frozen soils store billions of tons of carbon, just waiting to be unleashed3. So is there a way to save the permafrost? One team of researchers thinks it may have found a possible solution: big animals, herbivores—animals that eat only plants.

Back in 1996 researchers started an experiment called Pleistocene Park. They fenced in about eight square miles of land in northeast Siberia. And then they introduced different types of herbivores: reindeer4, horses, moose, bison, sheep and other large critters.

Since then, scientists have studied these animals’ effects on the ecosystem5. One outcome is that these large herbivores help keep the ground very cold—cooler than it would otherwise be.

“The snow in winter is important for soil temperature, because it acts as an insulating layer. So the air in winter, at the high latitudes6, is much colder than the soil.”

Philipp Porada, a vegetation ecologist at the University of Hamburg.

“So the idea of this experiment was to introduce large herbivores—and to quantify their effects on soil temperature to see if they can actually protect permafrost soils against thawing7. And this works because the animals increase snow density8 in winter by trampling9. And this leads to less insulation10 of the soil against cold air temperatures and results in a cooling effect.”

Freezing air reaches the soil more easily. Porada and his colleagues realized the significance of this effect, so they pulled data from Pleistocene Park, as well as from Sweden, to model what effect herbivores could have on permafrost if they lived in large numbers in the Arctic. The researchers found that even in a worst-case scenario11, some four degrees Celsius12 of global warming.

“These herbivores in the model reduce soil temperature substantially, by 1.7 degrees on average. And this leads to a preservation13 of around 80 percent of the original—today’s permafrost area. And without the herbivore effect in the model—so in the control run—we found that only 50 percent of the permafrost area would remain by the year 2100. So we can say that the effect of the herbivores in the model leads to a substantial preservation of permafrost soil.”

The study is in the journal Scientific Reports. [Christian Beer et al., Protection of permafrost soils from thawing by increasing herbivore density]

It may seem strange to have herds of horses and cold-adapted sheep grazing the Arctic tundra14. But then again, we’re living in strange times.

—Annie Sneed

[The above text is a transcript of this podcast.]


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1 herds 0a162615f6eafc3312659a54a8cdac0f     
兽群( herd的名词复数 ); 牧群; 人群; 群众
参考例句:
  • Regularly at daybreak they drive their herds to the pasture. 每天天一亮他们就把牲畜赶到草场上去。
  • There we saw herds of cows grazing on the pasture. 我们在那里看到一群群的牛在草地上吃草。
2 transcript JgpzUp     
n.抄本,誊本,副本,肄业证书
参考例句:
  • A transcript of the tapes was presented as evidence in court.一份录音带的文字本作为证据被呈交法庭。
  • They wouldn't let me have a transcript of the interview.他们拒绝给我一份采访的文字整理稿。
3 unleashed unleashed     
v.把(感情、力量等)释放出来,发泄( unleash的过去式和过去分词 )
参考例句:
  • The government's proposals unleashed a storm of protest in the press. 政府的提案引发了新闻界的抗议浪潮。
  • The full force of his rage was unleashed against me. 他把所有的怒气都发泄在我身上。 来自《简明英汉词典》
4 reindeer WBfzw     
n.驯鹿
参考例句:
  • The herd of reindeer was being trailed by a pack of wolves.那群驯鹿被一只狼群寻踪追赶上来。
  • The life of the Reindeer men was a frontier life.驯鹿时代人的生活是一种边区生活。
5 ecosystem Wq4xz     
n.生态系统
参考例句:
  • This destroyed the ecosystem of the island.这样破坏了岛上的生态系统。
  • We all have an interest in maintaining the integrity of the ecosystem.维持生态系统的完整是我们共同的利益。
6 latitudes 90df39afd31b3508eb257043703bc0f3     
纬度
参考例句:
  • Latitudes are the lines that go from east to west. 纬线是从东到西的线。
  • It was the brief Indian Summer of the high latitudes. 这是高纬度地方的那种短暂的晚秋。
7 thawing 604d0753ea9b93ae6b1e926b72f6eda8     
n.熔化,融化v.(气候)解冻( thaw的现在分词 );(态度、感情等)缓和;(冰、雪及冷冻食物)溶化;软化
参考例句:
  • The ice is thawing. 冰在融化。 来自《现代英汉综合大词典》
  • It had been snowing and thawing and the streets were sloppy. 天一直在下雪,雪又一直在融化,街上泥泞不堪。 来自英汉文学 - 嘉莉妹妹
8 density rOdzZ     
n.密集,密度,浓度
参考例句:
  • The population density of that country is 685 per square mile.那个国家的人口密度为每平方英里685人。
  • The region has a very high population density.该地区的人口密度很高。
9 trampling 7aa68e356548d4d30fa83dc97298265a     
踩( trample的现在分词 ); 践踏; 无视; 侵犯
参考例句:
  • Diplomats denounced the leaders for trampling their citizens' civil rights. 外交官谴责这些领导人践踏其公民的公民权。
  • They don't want people trampling the grass, pitching tents or building fires. 他们不希望人们踩踏草坪、支帐篷或生火。
10 insulation Q5Jxt     
n.隔离;绝缘;隔热
参考例句:
  • Please examine the insulation of the electric wires in my house.请检查一下我屋子里电线的绝缘情况。
  • It is always difficult to assure good insulation between the electric leads.要保证两个电触头之间有良好的绝缘总是很困难的。
11 scenario lZoxm     
n.剧本,脚本;概要
参考例句:
  • But the birth scenario is not completely accurate.然而分娩脚本并非完全准确的。
  • This is a totally different scenario.这是完全不同的剧本。
12 Celsius AXRzl     
adj.摄氏温度计的,摄氏的
参考例句:
  • The temperature tonight will fall to seven degrees Celsius.今晚气温将下降到七摄氏度。
  • The maximum temperature in July may be 36 degrees Celsius.七月份最高温度可能达到36摄氏度。
13 preservation glnzYU     
n.保护,维护,保存,保留,保持
参考例句:
  • The police are responsible for the preservation of law and order.警察负责维持法律与秩序。
  • The picture is in an excellent state of preservation.这幅画保存得极为完好。
14 tundra dmtwW     
n.苔原,冻土地带
参考例句:
  • The arctic tundra is at the top of the world around the North Pole.北极冻原是指北极点周边的地区,是世界最高的地方。
  • There is a large amount of methane gas under the Siberian tundra.西伯利亚的冻土地带之下有大量的甲烷气体。

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