Thu, Dec 15, 2011 - Page 15 News List

Naughty lemmings skew climate calculus
淘氣旅鼠影響氣候計算結果

This NASA image released Nov. 15 shows massive cloudbank sprawled over central Europe in early November, with clouds extending from the North Sea to the foothills of the Alps.
這張美國國家航空暨太空總署十一月十五日發布的照片,是十一月上旬在中歐上空從北海到阿爾卑斯山山麓飄散的雲層。

Photo: AFP
照片:法新社

Really, it is enough to drive a climate scientist over the edge.

In past years, satellite images have shown a perceptible growth in grasses and shrubs in parts of the Arctic, a phenomenon pinned on global warming. But part of the greening could come from lemmings, surprised researchers have found.

University of Texas scientists counted plant cover and biomass in a huge area in coastal Alaska where brown lemmings (Lemmus trimucronatus) have been monitored for more than 50 years in a project to understand their boom-and-bust population cycles.

On small plots that had been fenced off to exclude the lemmings, certain plant types called lichens and bryophytes had increased, the researchers found.

But where the lemmings scampered unhampered, there was an increase in grass and sedge — curiously, the very same plants that the hamster-like herbivores feed on.

The reason for this is unclear. Urine and feces from the lemmings could be acting as a fertilizer, helping the plants to grow, the researchers suggest.

Alternatively, the rodents could be chomping on the dead grass and sedge litter, which encourages new growth.

Either way, the findings pose a tundra conundrum. “We really need to be careful attributing the greening of the Arctic to global warming alone,” said the lead investigator, David Johnson.

(AFP)

說真的,這種事足以讓氣候科學家為之抓狂。

過去數年來,衛星影像一直顯示北極某些地區的草地與灌木出現明顯成長,這種現象被歸咎於是全球暖化的結果。但驚訝的研究人員卻發現,北極綠化的部分原因可能跟旅鼠有關。

德州大學科學家計算阿拉斯加沿岸一塊廣大地區的植被與生物質,科學家在此處監測褐旅鼠的活動已經逾五十年,目的是要了解旅鼠數量的起落循環。

研究人員發現,在用籬笆圍起來把旅鼠排除在外的小塊土地上,某些被稱為地衣與苔蘚的植物數量有所增加。

但在旅鼠可以自由蹦跳奔跑的地區,草地與莎草的數量反而增加;奇怪的是,這些植物正是這種類似倉鼠的食草動物的主食。

造成這種現象的原因不明。研究人員表示,旅鼠的糞尿可能變成了肥料,促進這些植物生長。

此外,這種囓齒動物也可能大口嚼食枯死的青草與莎草枯枝,鼓勵植物長出新芽。

TODAY’S WORDS 今日單字

1. pin on v. phr.

歸因於;怪罪於 (gui1 yin1 yu2; guai4 zui4 yu2)

例: You can’t pin the blame on her. She wasn’t even there when the accident happened.

(你不能把罪過怪到她頭上,意外發生時她根本不在場。)

2. boom-and-bust adj.

起落的;榮枯循環的 (qi3 luo4 de5; rong2 ku1 xun2 huan2 de5)

例: In the gold industry, boom-and-bust cycles last an average of 10 years.

(黃金產業的榮枯循環平均維持在十年左右。)

3. conundrum n.

難題 (nan2 ti2)

例: Arranging childcare over the school holidays can be quite a conundrum for working parents.

(要在學校放假日安排安親照顧,對必須工作的家長而言是一大難題。)


不論如何,這些研究結果都形成了一個凍原難題。「我們在把北極綠化現象歸咎於全球暖化這個單一原因時,真的必須非常謹慎,」研究主持人強森表示。

(翻譯/法新社:俞智敏)

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