手機APP下載

您現在的位置: 首頁 > 在線廣播 > 科學美國人 > 科學美國人地球系列 > 正文

科學美國人60秒:食草動物有助于保護永久凍土

來源:可可英語 編輯:aimee ?  VIP免費外教試聽課 |  可可官方微信:ikekenet
  


掃描二維碼可進行跟讀訓練
  下載MP3到電腦  [F8鍵暫停/播放]   批量下載MP3到手機
E~S#ooS559Di4z~

vY@x)#,SWeD

This is Scientific American's 60-second Science, I'm Annie Sneed.
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 unleashed. 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: reindeer, horses, moose, bison, sheep and other large critters.
Since then, scientists have studied these animals' effects on the ecosystem. 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 latitudes, is much colder than the soil."
Philipp Porada, a vegetation ecologist at the University of Hamburg.

|0J~[IEJhaLSyFHu

馴鹿.jpg
"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 thawing. And this works because the animals' trampling, and this leads to less insulation 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 scenario, some four degrees Celsius of global warming:
"These herbivores in the model reduce soil temperature substantially, by 1.7 degrees on average. And this leads to a preservation 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.
It may seem strange to have herds of horses and cold-adapted sheep grazing the Arctic tundra. But then again, we're living in strange times.
Thanks for listening for Scientific American — 60-Second Science. I'm Annie Sneed.

IH*npkd9j^^ypAu

1bpIP(~Zzye=|I

_!P-%~,XSSQ3Bn+(||2E6j@vE=EY~pc7Z-&TXhdSV_y25F!

重點單詞   查看全部解釋    
plain [plein]

想一想再看

n. 平原,草原
adj. 清楚的,坦白的,簡

 
original [ə'ridʒənl]

想一想再看

adj. 最初的,原始的,有獨創性的,原版的

聯想記憶
preservation [.prezə'veiʃən]

想一想再看

n. 保存

 
grazing ['ɡreiziŋ]

想一想再看

n. 牧草;放牧 v. 擦過;抓傷(graze的現在分詞

 
layer ['leiə]

想一想再看

n. 層
vi. 分層
vt. 將某

聯想記憶
outcome ['autkʌm]

想一想再看

n. 結果,后果

 
solution [sə'lu:ʃən]

想一想再看

n. 解答,解決辦法,溶解,溶液

聯想記憶
cattle ['kætl]

想一想再看

n. 牛,家畜,畜牲

 
quantify ['kwɔntifai]

想一想再看

v. 定量,表示份量,稱量,量化

 
ecosystem ['ekəusistəm]

想一想再看

n. 生態系統

 
?
發布評論我來說2句

    最新文章

    可可英語官方微信(微信號:ikekenet)

    每天向大家推送短小精悍的英語學習資料.

    添加方式1.掃描上方可可官方微信二維碼。
    添加方式2.搜索微信號ikekenet添加即可。
    久久国产自偷自偷免费一区,久久久久久精品免费免费,久久综合色超碰人人