由于二氧化碳消除了温暖的半干旱草原的干燥,C4草繁荣
Jack A Morgan1, Daniel R LeCain, Elise Pendall
1USDA-ARS, Rangeland Resources Research Unit and Northern Plains Area, Fort Collins, Colorado 80526, USA. jack.morgan@ars.usda.gov
Nature
|August 5, 2011
概括
二氧化碳 (CO2) 水平的上升可以抵消全球变暖对半干旱草原的影响. 增加的二氧化碳提高了植物的用水量和生产力,抵消了由变暖引起的干燥,并有利于特定的草类型.
科学领域:
- 生态生态学 生态生态学
- 气候变化生物学 气候变化生物学
- 植物生理学 植物生理学
背景情况:
- 全球变暖增加了蒸发需求,可能导致广泛的干旱.
- 大气中二氧化碳 (CO2) 的增加可能会提高植物的用水效率,但由于生物质的增加和植物群落组成的改变,其净效果是不确定的.
- 预计变暖将有利于C4草,而高CO2预计将有利于C3植物.
研究的目的:
- 研究二氧化碳增加和温和变暖对土壤水含量 (SWC) 和半干旱草原中的植物群体动态的相互作用影响.
- 为了确定二氧化碳增强的用水效率是否可以减轻气候变暖引起的干燥.
- 评估二氧化碳增加和气候变暖如何影响C3和C4草的竞争.
主要方法:
- 在半干旱的草原中,对二氧化碳水平进行实验操纵,达到600ppm,日夜变暖1.5°C/3.0°C.
- 对土壤含水量 (SWC) 的监测.
- 评估植物群体组成 (C3和C4草) 和地表生产力.
主要成果:
- 仅仅二氧化碳的增加就增加了SWC,而仅仅升温就导致了干燥.
- 结合二氧化碳增加和变暖,与对照地块相比,SWC没有显著变化.
- 增加的二氧化碳有利于C3草和提高整体生产率,而变暖有利于C4草.
- 随着气候变暖和二氧化碳的丰富,在土壤水分有限的年份刺激了C4草的生长.
结论:
- 升高的二氧化碳可以抵消半干旱草原中温和变暖的干燥效应.
- 尽管生物质可能增加,但在未来的气候情景下,二氧化碳的增加可以提高水的可用性和生产力.
- 半干旱的草原可能表现出比之前预期的更高的土壤含水量和生产力,在一个富含二氧化碳,更温暖的世界.
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