Drivers of ecosystem and climate change in tropical West Africa over the past ~540 000 years
Drivers of ecosystem and climate change in tropical West Africa over the past ~540 000 years
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过去约 54 万年热带西非生态系统和气候变化的驱动因素
DOI：
10.1002/jqs.2893
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发表时间：
2016
影响因子：
2.3
通讯作者：
Miller C
中科院分区：
文献类型：
--
作者：
Miller C
缺乏经验的非海洋数据意味着，气候变化对上一次冰期以后热带地区陆地生态系统的影响存在不确定性。博苏姆特维撞击坑(加纳)的沉积填充物提供了西非最长的连续第四纪陆地环境变化档案，跨越了最后的∼108万年。在这里，我们利用花粉分析和博苏姆特维湖沉积物中保存的大量有机质的氮同位素组成，探索过去∼54万年来热带西非生态系统和气候变化的驱动因素。草花粉丰度的变化(0−99%)表明草地和森林之间的过渡。有机质氮同位素组成的同时代变化表明，草地扩张的间隔期与最低湖泊水位和低区域水分有效性相吻合。观测到的变化响应了全球气候在冰期-间冰期和较短时间尺度上的轨道速度变化。重要的是，我们的数据揭示的生态系统变化的幅度超过了以前根据海洋记录确定的变化幅度，首次表明热带低地生态系统对第四纪气候变化高度敏感。
A paucity of empirical non‐marine data means that uncertainty surrounds the impact of climate change on terrestrial ecosystems in tropical regions beyond the last glacial period. The sedimentary fill of the Bosumtwi impact crater (Ghana) provides the longest continuous Quaternary terrestrial archive of environmental change in West Africa, spanning the last ∼1.08 million years. Here we explore the drivers of change in ecosystem and climate in tropical West Africa for the past ∼540 000 years using pollen analysis and the nitrogen isotope composition of bulk organic matter preserved in sediments from Lake Bosumtwi. Variations in grass pollen abundance (0−99%) indicate transitions between grassland and forest. Coeval variations in the nitrogen isotopic composition of organic matter indicate that intervals of grassland expansion coincided with minimum lake levels and low regional moisture availability. The observed changes responded to orbitally paced global climate variations on both glacial–interglacial and shorter timescales. Importantly, the magnitude of ecosystem change revealed by our data exceeds that previously determined from marine records, demonstrating for the first time the high sensitivity of tropical lowland ecosystems to Quaternary climate change.