Abstract Paleoenvironmental reconstructions based on Amazonian fluvial and marine pollen data are often hindered due to the scarcity of modern calibration data. In Amazonia, rivers are the main pathways for pollen from upland and flooded forests to continental and marine sediment sinks. Linking pollen assemblages transported by rivers to watershed vegetation is crucial to interpret palynological archives. In order to constrain the interpretation of palynological archives, we analysed the pollen content of 36 riverbed sediment samples distributed from the mouth of the Ica River (ca. 68oW) to the Amazon estuary (ca. 49oW) with support of grain size and major element analyses of the inorganic sedimentary content. The palynological analysis shows a strong imprint of the lowland floodplain vegetation as the main source of the riverborne pollen. The upper reaches of the Amazon River present abundant Cecropia, reflecting early-successional stages induced by intense floodplain disturbance. The middle and lower reaches of the Amazon River exhibit a progressive increase in herbs mainly represented by Poaceae and Cyperaceae, related to wider floodplains covered by seasonally inundated vegetation. Floodplain forests of whitewater rivers (varzeas) are palynologically characterized by Iriartea, Mauritia, Ilex, Pseudobombax, Acalypha, and Luehea/Laetia, with high frequency of Cecropia or herbs, and montane taxa. At the black- and clearwater rivers, the igapo floodplain forests provide high percentages of Symmeria, Myrtaceae, and Alchornea, and can be distinguished by Sapium/Sebastiana, Piranhea, Amanoa, Pouteria, Ferdinandusa/Genipa, Attalea/Astrocaryum, and Eschweilera which suggest conditions of higher stability and mature forests. Contribution from the non-flooded uplands, Andean Mountains, and savannas/Cerrado occur, but their signals are blurred by the high pollen production of the lowland floodplains. Our data provide a calibration set for environmental reconstructions of river-influenced deposits across the Amazon including offshore areas of the most iconic riverine dominated landscape in the world.

中文翻译：

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亚马逊河流的现代花粉特征和环境重建的新见解

摘要 由于现代校准数据的稀缺，基于亚马逊河流和海洋花粉数据的古环境重建经常受到阻碍。在亚马逊河流域，河流是花粉从高地和淹没森林到大陆和海洋沉积物汇的主要途径。将河流运输的花粉组合与流域植被联系起来对于解释孢粉学档案至关重要。为了限制孢粉档案的解释，我们分析了分布于伊卡河口（约 68oW）到亚马逊河口（约 49oW）的 36 个河床沉积物样品的花粉含量，并支持粒度和主要元素无机沉积物含量分析。孢粉学分析表明，低地漫滩植被是河流花粉的主要来源。亚马逊河上游有丰富的天蚕，反映了强烈的洪泛区扰动引起的早期连续阶段。亚马逊河中下游的草本植物逐渐增加，主要以禾本科和莎草科为代表，这与被季节性淹没植被覆盖的更广阔的漫滩有关。白水河（varzeas）的漫滩森林在孢粉学上以 Iriartea、Mauritia、Ilex、Pseudobombax、Acalypha 和 Luehea/Laetia 为特征，以高频率的 Cecropia 或草本植物以及山地分类群为特征。在黑水河和清水河，伊加波漫滩森林提供高比例的 Symmeria、桃金娘科和 Alchornea，可以通过 Sapium/Sebastiana、Piranhea、Amanoa、Pouteria、Ferdinandusa/Genipa、Attalea/Astrocaryum 区分 和 Eschweilera 表明更高的稳定性和成熟森林的条件。来自未淹没高地、安第斯山脉和热带草原/塞拉多的贡献发生了，但它们的信号被低地洪泛平原的高花粉产量所模糊。我们的数据为整个亚马逊地区受河流影响的沉积物的环境重建提供了校准集，包括世界上最具标志性的河流主导景观的近海地区。