Global warming might seem like a botanical boon. After all, milder temperatures and more carbon dioxide and nitrogen should feed flora. But a ten-year study has found that any initial positive effect on plant growth from climate change may soon disappear. The report is in the journal Nature Climate Change.
全球变暖对植物而言似乎是个福音。毕竟，温和的气候和日渐增多的二氧化碳和氮可以给植物提供养料。但一项为期十年的研究发现，任何气候变化对植物生长产生的最初积极影响可能很快就会消失。该报告发布在《自然气候变化》杂志上。

Researchers transplanted vegetation from four grassland ecosystems to lower, warmer elevations. They also modified the precipitation at the transplant sites based on altered rainfall estimates. For the first year, the plants did great, producing more biomass and churning out more oxygen for us. But their productivity went down for the rest of the decade.
研究人员将四个草场生态系统的植被移植到海拔较低、较温暖的地域。根据预期的降雨量变化，他们还改变了移植地的降水量。第一年，植物长势确实很好，产量很高，也给我们制造了更多的氧气。但这些植物的生产能力在这十年的剩余时间里却降低了。

What happened? Warming did speed up the nitrogen cycle, which should have increased nitrogen’s availability as plant fertilizer. But a lot of the nitrogen left the soil through run-off or uptake into the atmosphere. In addition, productive native plants began to lose out to species that thrive at higher temperatures, but are less productive than the natives. Warmer temperatures may spur immediate growth, but in the long term, we can’to expect plants to like it hot.
这是怎么回事？原来，气候变暖也加快了氮循环，这可以使更多的氮气用作植物的肥料，但也有大量的氮从土壤中溢出或者流入大气层中。此外，多产的的原生植物在竞争中开始输给那些可以在较高温度下茁壮成长的植物物种，但仍然低于原生植物原本的产量。气温升高可以迅速刺激植物增长，但是从长远来看，温度上升可不是植物们所喜欢的。