Wed, Sep 25, 2013 - Page 10 News List

Big animals crucial for fertility of soils: study
研究︰大型動物對土壤肥力至關重要

Photo:AFP 法新社

The mass extinction of large animals in the Pleistocene epoch caused today’s dearth of soil nutrients, scientists said, and warned of further damage if modern giants like the elephant disappear.

The Pleistocene epoch, which dated from about 2.6 million to 11,700 years ago, saw large animals dubbed megafauna take over domination of the planet from extinct dinosaurs, only to die out en masse themselves.

During their peak, much of the world resembled a modern-day African savannah.

South America, for example, was teeming with 5-tonne ground sloths, armadillo-like glyptodons the size of a small car, and herds of elephant-like cuvieronius and stegomastodons.

These megafauna, animals weighing more than 44kg, played a key role in fertilizing soil far away from the areas near rivers where they fed — plowing the nutrients they consumed back into circulation through their dung or their decomposing bodies when they died.

Large animals ate much more and traveled further than small ones, and were mainly responsible for long-distance fertilization, said a study published in the journal Nature Geoscience.

“Big animals are like the nutrient arteries of the planet and if they go extinct it is like severing these arteries,” co-author Chris Doughty of the University of Oxford’s Environment Change Institute said.(AFP)

科學家指出,更新世時期大型動物的大滅絕導致現今土壤養分不足,並警告一旦大象之類的現代巨大動物消失,將進一步損及地力。

距今兩百六十萬至一萬一千七百年前的更新世時期,經歷了稱為「巨型動物」的大型動物在恐龍滅絕後接管地球,卻集體絕跡的現象。

在牠們最活躍的時期,世界許多地區類似現代的非洲大草原。

例如,五公噸重的巨爪地懶,約一輛小車大、類似犰狳的雕齒獸,以及類似大象的成群居維象與劍乳齒象等,在南美各地四處橫行。

這些重逾四十四公斤的巨型動物,在使遠離其覓食的濱河地區土壤肥沃上扮演重要角色─經由牠們的糞便與其死後分解的屍體,將牠們消耗的養分進入地力的循環中。

大型動物遠比小型動物吃得多、移動較遠,主要負責遠距施肥,這篇發表在《自然地球科學》期刊的研究指出。

報告共同作者、牛津大學環境變遷研究所的克里斯.道提說:「大型動物如同地球的養分要道,如果牠們滅絕,就如同砍斷這些幹道。」(法新社/翻譯:魏國金)

TODAY’S WORDS 今日單字

1. dearth n.

缺乏;不足 (que1 fa2; bu4 zu2)

例: They suffer from a dearth of resources.

(他們飽受資源不足之苦。)

2. en masse adv. Phr.

全體地;一同地 (quan2 ti3 de5; yi1 tong2 de5)

例: The people rioted en masse.

(人們同聲歡呼。)

3. teem with v. phr.

充滿 (chong1 man3)

例: This river is teeming with fish.

(這條河魚很多。)


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