時差N小時:二氧化碳增加食欲
二氧化碳是一種強力的溫室氣體。
Levels of carbon dioxide, or CO2, in the atmosphereare increasing at an unprecedented rate.
大氣中的二氧化碳的濃度正在以前所未有的速度增長。
But what impact do higher CO2 levels have onplants?
但是空發(fā)中高濃度的二氧化碳對植物有什么樣的影響呢?
Plants use CO2 from the air along with sunlight andwater to produce carbohydrates they use for energy.
植物運用空氣中的二氧化碳，與陽光、水一起產(chǎn)生能量所需的碳水化合物。
This process is called photosynthesis.
這個過程叫做光合作用。
Higher atmospheric CO2 increases the rate of photosynthesis, and thus the amount ofcarbohydrates in plant leaves.
二氧化碳濃度較高的大氣增加了光合作用的速率，因此植物中碳水化合物的數(shù)量就會過剩。
Sounds beneficial, right?
聽起來很有利，對吧?
However, scientists have found that asCO2 levels go up, plant defenses might go down.
然而科學(xué)家們發(fā)現(xiàn)隨著二氧化碳濃度的升高，植物的防御將會降低。
Researchers at the University of Illinois used a special open-air research facility that allowedthem togrow soybean plants in different concentrations of CO2—without changing other factorssuch assunlight, insects or rainfall.
伊利諾伊大學(xué)的研究人員采用了特殊的露天研究設(shè)施，這些設(shè)施可以使他們在不同濃度的二氧化碳中種植大豆植物-不用改變其他的因素，如陽光，昆蟲，或者雨水。
They discovered that soybeans grown in fields with higher CO2 levels had much moreinsectdamage and attracted more adult insect pests than those in plots with less CO2 in the air.
他們發(fā)現(xiàn)在較高濃度二氧化碳中種植的大豆會遭受更嚴重的蟲害，與在空氣中二氧化碳濃度較低的地方相比，它們會吸引更多的成年害蟲。
The insects might have been attracted by the higher carbohydrate levels in the leaves ofplantsgrown in high CO2.
這些昆蟲被植物葉子中由高濃度的二氧化碳產(chǎn)生的高含量的碳水化合物所吸引。
But a higher carb diet wasn't the only thing that encouraged infestation.
但是高碳水化合物的飲食并不是引起蟲害的唯一原因。
Normally, soybean plants under attack by insects will produce jasmonic acid.
一般來說，被昆蟲攻擊的大豆植物都會產(chǎn)生抑制昆蟲消化葉子能力的茉莉酸，
This inhibits theinsects'ability to digest leaves, which protects the plant from further attack.
以保護植物免受進一步的損害。
In high CO2 atmospheres, the plants were unable to produce this defensive chemical.
在高二氧化碳環(huán)境中，植物無法產(chǎn)生這種防御性化學(xué)物質(zhì)。
So, the dangers of rapidly increasing CO2 in our atmosphere might extend beyond climatechange.
所以二氧化碳急速增長所帶來的危害可能遠遠不止氣候變化。
Since soybeans grown at higher CO2 would lose a crucial defense pathway and attractmorehungry beetles, other food crops might also be more vulnerable if CO2 levels continue torise.
既然在高二氧化碳環(huán)境中種植的大豆會失去防御的關(guān)鍵通道并引來更多饑餓的甲蟲，如果二氧化碳濃度繼續(xù)升高的話，其它糧食作物可能也會變得更加脆弱。
