227 tree species dominate Amazon landscape 兩百二十七種樹種主控亞馬遜地景

A student and professor cover dry leaf samples with bags as they study climate change in the Amazon rainforest at Tambopata National Reserve in Madre de Dios, Peru on Dec. 3 last year.
一位學生與一位教授去年十二月三日在祕魯馬德雷德迪奧斯區坦波巴塔國家保護區研究亞馬遜雨林的氣候變化時用袋子蓋住乾樹葉樣本。

Photo: Reuters
照片：路透

Despite being home to about 16,000 tree species, just 227 “hyperdominant” species account for half of Amazonia’s total trees, a study suggests.

An international team of researchers found that the region was, in total, home to an estimated 390 billion trees. Writing in Science, they added that the rarest 11,000 species made up only 0.12% of the tree cover.

The results were based on a survey of 1,170 plots and half a million trees across the six million square kilometer area, often described as the lungs of the world.

The authors said that the underlying cause of the hyper dominance of the 227 species, which accounted for 1.4% of the estimated number of species in the region, remained unknown.

The lead author Hans ter Steege said, “We don’t really know why these species are so incredibly dominant because they do not have any particular ecological feature that stands out.”

The most dominant species was identified as Euterpe precatoria, a palm tree native to central and southern America, with a mean estimate population of more than five billion individuals within Amazonia.

Conversely, the researchers noted that the rarest 5,800 species had communities with fewer than 1,000 individuals.

(Liberty Times)

TODAY’S WORDS
今日單字

1. dominate v.

佔主要地位；支配；控制

(zhan4 zhu3 yao4 di4 wei4; zhi1 pei4; kong4 zhi4)

例: Taipei 101 dominates the Taipei skyline.

(台北１０１是台北天際的首要標的。)

2. account for adj.

佔；做出說明 (zhan4; zuo4 chu1 shuo1 ming2)

例: Police said that the identities of 46 people are still not accounted for.

(警方表示仍有四十六人身分不明。)

3. stand out v. phr.

醒目；突出；傑出 (xing3 mu4; tu2 chu1; jie2 chu1)

例: She stood out among the students by her self-discipline.

(在學生群中，她的自律使她與眾不同.)

儘管孕育約一萬六千種樹種，但僅只兩百二十七種「超優勢」樹種就佔了亞馬遜雨林所有林木的半數，研究推測。

一支國際研究團隊發現，該區域估計共有約三千九百億棵樹。在這篇發表於「科學」期刊的研究中，他們補充說，最罕見的一萬一千種樹種僅佔植被的百分之零點一二。

相關結果奠基於對這塊佔地廣達六百萬平方公里區域內的一千一百七十處林區、五十萬棵樹的調查，該區常被稱為世界之肺。

作者群指出，這兩百二十七種樹種的超優勢根本原因仍然不明。這些樹種佔該區推估的樹種量的百分之一點四。

研究主要撰文者漢斯．德．史提吉說︰「我們真的不知道為何這些樹種如此不可思議地佔優勢，因為它們並無任何突出的特定生態特性。」

最優勢的樹種被鑑別出為「串珠埃塔棕」，這種原產於中美與南美的棕櫚樹，在亞馬遜雨林內平均估計超過五十億棵。

相反的，研究人員指出，最罕見的五千八百種樹種，其樹群不到一千棵。

（自由時報／翻譯：魏國金）