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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Fire cycles in North American interior grasslands and their relation to prairie drought
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Fire cycles in North American interior grasslands and their relation to prairie drought

机译：北美室内草原的火灾周期及其与草原干旱的关系

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High-resolution analyses of a late Holocene core from Kettle Lake in North Dakota reveal coeval fluctuations in loss-on-ignition carbonate content, percentage of grass pollen, and charcoal flux. These oscillations are indicative of climate-fuel-fire cycles that have prevailed on the Northern Great Plains (NGP) for most of the late Holocene. High charcoal flux occurred during past moist intervals when grass cover was extensive and fuel loads were high, whereas reduced charcoal flux characterized the intervening droughts when grass cover, and hence fuel loads, decreased, illustrating that fire is not a universal feature of the NGP through time but oscillates with climate. Spectral and wavelet analyses reveal that the cycles have a periodicity of approximate to 160 yr, although secular trends in the cycles are difficult to identify for the entire Holocene because the periodicity in the early Holocene ranged between 80 and 160 yr. Although the cycles are evident for most of the last 4,500 yr, their occasional muting adds further to the overall climatic complexity of the plains. These findings clearly show that the continental interior of North America has experienced short-term climatic cycles accompanied by a marked landscape response for several millennia, regularly alternating between dual landscape modes. The documentation of cycles of similar duration at other sites in the NGP, western North America and Greenland suggests some degree of regional coherence to climatic forcing. Accordingly, the effects of global warming from increasing greenhouse gases will be superimposed on this natural variability of drought.
机译：对北达科他州Kettle Lake晚新世岩心的高分辨率分析显示，燃烧后碳酸盐含量，草粉百分比和木炭通量的年代际波动。这些振荡表明，大部分新世晚期都在北部大平原（NGP）盛行。在过去的潮湿间隔中，草覆盖广泛且燃料负荷高时，发生了较高的木炭通量；而当草覆盖度降低，从而导致燃料负荷降低时，木炭通量的减少则说明了干旱的发生，这说明火灾不是NGP的普遍特征。时间，但随着气候而振荡。频谱和小波分析表明，这些周期的周期约为160年，尽管很难对整个全新世确定周期的长期趋势，因为早期全新世的周期介于80至160年之间。尽管在过去的4,500年的大部分时间里这些周期都是明显的，但偶尔的静音会进一步增加平原的整体气候复杂性。这些发现清楚地表明，北美大陆内部经历了短暂的气候周期，并伴随着明显的景观响应长达几千年，并且在两种景观模式之间定期交替。在NGP，北美西部和格陵兰岛其他站点，类似持续时间的周期记录表明，区域在一定程度上与气候强迫有关。因此，温室气体增加引起的全球变暖的影响将叠加在干旱的这种自然变化上。

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