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Ecosystems Still Feel the Pain of Ancient Extinctions
物種滅絕對生態(tài)系統(tǒng)仍然存在影響
It's not just humans that still feel the effects of a trauma many years later,ecosystems do too.
若干年后，不僅人類仍然會感覺到創(chuàng)傷所帶來的影響，生態(tài)系統(tǒng)同樣也會。
Thousands of years after human hunters wiped out big land animals like giant ground sloths,the ecosystems they lived in are still feeling the effects.
在人類捕獵者消滅了大型陸地動物如巨型地懶的數(shù)千年后，人們居住的生態(tài)系統(tǒng)仍然能感覺到這些影響。
Many ecosystems rely on big animals to supply them with nutrients, mostly from dung.
許多生態(tài)系統(tǒng)都依賴于大型動物來為它們提供營養(yǎng)物質(zhì)，這些物質(zhì)主要從糞便中獲得。
"If you remove the big animals from an ecosystem, you pretty much stop nutrients moving,"says Chris Doughty of the University of Oxford.
牛津大學的克里斯·道蒂說“如果你從生態(tài)系統(tǒng)里消除大型動物，那么你幾乎就停止了養(yǎng)分的運送。”
Doughty and colleagues simulated the distribution of phosphorus,a nutrient that plants need to grow in the Amazon basin in South America.
道蒂和他的同事在南美洲亞馬遜河流域仿造了磷的分布規(guī)律，磷是植物生長所需要的養(yǎng)分。
This area was once home to spectacularly large animals, including the elephant—like gomphotheres and giant ground sloths.
這一地區(qū)曾經(jīng)是很多大型動物的家園，包括與大象類似的嵌齒象科和巨型地懶。
But 12500 years ago, around the time humans moved into South America, these huge animals all died out, hit by a double whammy of being hunted and a changing climate.
但在12500年前，也就是大約在人類搬進南美的時候，這些巨型動物都滅絕了，主要是受到了獵殺和氣候變化雙重災難的影響。
Nowadays the Amazon is still home to a huge diversity of animals.
如今，亞馬遜仍然是很多不同種類動物的家園。
"But these extinctions cut out all the big animals, "says Doughty.
道蒂說“但這些滅絕已經(jīng)消滅了所有的大型動物。”
It seems the mass extiction had a profound effect on how phosphorus is spread around the Amazon basin.
似乎看來大量動物滅絕對亞馬遜河流域磷的分布有著深遠的影響。
Nutrients are released when rocks are eroded, and then get distribute onto floodplains by rivers.
當巖石被侵蝕時，營養(yǎng)物質(zhì)被釋放出來，然后隨著河流分布到?jīng)_積平原。
In South America, the most phosphorus rich soils are found near the Andes mountain chain in the west.
在南美洲，西部的安第斯山脈被發(fā)現(xiàn)擁有富含磷最多的土壤。
If Doughty is right, the Amazon is still changing in response to the extinction.
如果道蒂的觀點是正確的，為了回應這種滅絕，亞馬遜仍然在改變著。
He estimates the spread of nutrients will keep getting patchier for another 17 000 years,
他估計，再過17000年，營養(yǎng)的傳播將會變得更加不規(guī)則，
although the effect will likely be dwarfed by the impacts of deforestation and climate change in the short term.
雖然這種影響相對于短期內(nèi)的森林砍伐和氣候變化所帶來的后果會顯得相形見絀。
