A 1.8 million year history of Amazon vegetation
A 1.8 million year history of Amazon vegetation
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DOI：
10.1016/j.quascirev.2022.107867
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发表时间：
2023-01
影响因子：
4
通讯作者：
A. Kern;T. Akabane;Jaqueline Q. Ferreira;C. Chiessi;D. Willard;Fabricio Ferreira;Allan Oliveira Sanders;C. G. Silva;C. Rigsby;F. Cruz;G. Dwyer;S. Fritz;P. A. Baker
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文献类型：
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作者：
A. Kern;T. Akabane;Jaqueline Q. Ferreira;C. Chiessi;D. Willard;Fabricio Ferreira;Allan Oliveira Sanders;C. G. Silva;C. Rigsby;F. Cruz;G. Dwyer;S. Fritz;P. A. Baker
在更新世期间，全球气候的长期趋势受轨道周期的控制，导致了高幅度的冰川-间冰期变化。这一时期亚马逊河流域植被的历史在很大程度上是未知的，因为没有连续的记录从低地盆地延伸明显超过末次冰期。在这里，我们提出了一个古环境记录跨越过去的1800 kyr的基础上，孢粉学数据，生物群落重建，和生物多样性指标，从海洋沉积物的核心，保留了连续档案的沉积物从亚马逊河。热带雨林占主导地位的亚马逊低地在过去的1800 ka与周围的暖温带雨林和热带季节性森林的交换。在1800和1000 ka之间，雨林生物群系存在于亚马逊流域，沿着广泛的河岸湿地植被。热带雨林的扩张发生在相对温暖的海洋同位素阶段33和31（约1000年）。1110年至1060年），其次是收缩的森林和湿地，直到约。800 ka.在800和400万年之间，低花粉浓度和低多样性的孢粉组合，使亚马逊河流域植被的解释困难。400 ka左右，植被变化与冰期-间冰期全球气候循环之间存在较强的同步性。400 ka后，间冰期植被占主导地位的低地热带雨林与温暖的温度和较高的CO2。在较低的温度和较低的CO2的冰川阶段，热带季节性森林扩大，大概是向亚马逊河流域东部。虽然这项研究没有提供任何证据支持在冰川期亚马逊低地的稀树草原或草原植被的显着扩张，有变化的雨林组成中的一些部分的盆地朝向更高比例的落叶元素，指向不太潮湿的条件和/或更大的季节性降水。然而，雨林在冰期和间冰期都持续存在。这些研究结果证实了热带低地植被对CO2、温度和湿度变化的敏感性，以及在中更新世过渡期最温暖的阶段和过去400 kyr的间冰期阶段发生的最适合热带雨林的条件。
During the Pleistocene, long-term trends in global climate were controlled by orbital cycles leading to high amplitude glacial-interglacial variability. The history of Amazonian vegetation during this period is largely unknown since no continuous record from the lowland basin extends significantly beyond the last glacial stage. Here we present a paleoenvironmental record spanning the last 1800 kyr based on palynological data, biome reconstructions, and biodiversity metrics from a marine sediment core that preserves a continuous archive of sediments from the Amazon River.Tropical rainforests dominated the Amazonian lowlands during the last 1800 ka interchanging with surrounding warm-temperate rainforests and tropical seasonal forests. Between 1800 and 1000 ka, rainforest biomes were present in the Amazon drainage basin, along with extensive riparian wetland vegetation. Tropical rainforest expansion occurred during the relatively warm Marine Isotope Stages 33 and 31 (ca. 1110 to 1060 ka), followed by a contraction of both forests and wetlands until ca. 800 ka. Between 800 and 400 ka, low pollen concentration and low diversity of palynological assemblages renders difficult the interpretation of Amazonian vegetation. A strong synchronicity between vegetation changes and glacial-interglacial global climate cycles was established around 400 ka. After 400 ka, interglacial vegetation was dominated by lowland tropical rainforest in association with warmer temperatures and higher CO2. During cooler temperatures and lower CO2of glacial stages, tropical seasonal forests expanded, presumably towards eastern Amazonia. While this study provides no evidence supporting a significant expansion of savanna or steppe vegetation within the Amazonian lowlands during glacial periods, there were changes in the rainforest composition in some parts of the basin towards a higher proportion of deciduous elements, pointing to less humid conditions and/or greater seasonality of precipitation. Nevertheless, rainforest persisted during both glacial and interglacial periods. These findings confirm the sensitivity of tropical lowland vegetation to changes in CO2, temperature, and moisture availability and the most suitable conditions for tropical rainforests occurred during the warmest stages of the Mid Pleistocene Transition and during the interglacial stages of the past 400 kyr.