Study： Just 227 tree species dominate Amazon landscape
研究︰僅只227種樹種主控亞馬遜地景
2013-10-23◎魏國金
Despite being home to about 16,000 tree species, just 227 "hyperdominant" species account for half of Amazonia’s total trees, a study suggests.
儘管孕育約1萬6000種樹種，但僅只227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。
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 tree cover.
一支國際研究團隊發現，該區域估計共有約3900億棵樹。在這篇發表於「科學」期刊的研究中，他們補充說，最罕見的1萬1000種樹種僅佔植被的0.12％。
The results were based on a survey of 1,170 plots and half-a-million trees across the six-million-square-kilometre area, often described as the lungs of the world.
相關結果奠基於對這塊佔地廣達600萬平方公里區域內的1170處林區、50萬棵樹的調查，該區常被稱為世界之肺。
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.
作者群指出，這227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1.4％。
The lead author Dr. 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."
研究主要撰文者漢斯．德．史提吉博士說︰「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。」
The most dominant species was indentified 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.
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50億棵。
Conversely, the researchers noted that the rarest 5,800 species had communities with fewer than 1,000 individuals.
相反的，研究人員指出，最罕見的5800種樹種，其樹群不到1000棵。
新聞辭典
hyper–︰有超出、高於、過度之意。例如︰hypercorrect（矯枉過正的）、hypercritical（吹毛求疵的）。
account for︰動詞片語，（數量、比例）佔，也有做出說明之意。例句︰Police said that 46 persons are still not accounted for.（警方表示仍有46人身分不明。）
stand out︰動詞片語，醒目、突出、傑出。例句︰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。）
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