To describe the composition of the penultimate glacial Brazilian Atlantic forest, we analyzed pollen, charcoal and diatoms deposited in the section from 871 to 1400 cm of core CO14 drilled in the Colônia basin in southeastern Brazil. The landscape was characterized by a cool grassland with three conifer genera: Araucaria, Podocarpus and Ephedra. Total arboreal pollen frequency did not change during the transition from glacial to interglacial conditions. Changes in Podocarpus frequency and concentration showed out-of-phase responses with austral summer insolation at an orbital scale while, at a millennial scale, both northern and southern hemisphere ice volume controlled the interplay between positions of the Inter-Tropical Convergence Zone and South Tropical Front (STF), which in turn defined the latitudinal distribution of rainfall. The disappearance of Podocarpus and the decrease of Araucaria observed between ~167 and 160 ka were related to a dry interval which was not observed elsewhere. During Termination II a progressive decrease in conifer pollen taxa was in phase with a southward shift in the STF and increase in Atlantic sea surface temperatures. Our results show that southern hemisphere conifer distribution is strongly linked to austral summer insolation and winter precipitation and will be threatened by the southward expansion of the summer rainfall boundary.

中文翻译：

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倒数第二次更新世冰川期及其结束期间的巴西南部热带森林

为了描述巴西大西洋倒数第二个冰川森林的组成，我们分析了在巴西东南部科洛尼亚盆地钻取的 CO14 核心 871 至 1400 厘米部分沉积的花粉、木炭和硅藻。该地貌的特点是凉爽的草原，生长着三种针叶树属：南洋杉、罗汉松和麻黄。从冰期到间冰期的过渡期间，总树栖花粉频率没有变化。罗汉松频率和浓度的变化在轨道尺度上表现出与南方夏季日照的异相响应，而在千年尺度上，北半球和南半球的冰量控制了热带辐合带和南热带辐合带位置之间的相互作用。锋面 (STF)，它又定义了降雨的纬度分布。在大约 167 至 160 ka 之间观察到的罗汉松的消失和南洋杉的减少与其他地方没有观察到的干旱期有关。在第二次终止期间，针叶树花粉类群的逐渐减少与STF南移和大西洋海面温度的上升同步。我们的研究结果表明，南半球针叶树分布与南方夏季日照和冬季降水密切相关，并将受到夏季降雨边界南扩的威胁。