Reconstrucción de la vegetación posglacial y su relación con el ascenso relativo del nivel del mar en el extremo este del canal Beagle, Tierra del Fuego, Argentina
Reconstrucción de la vegetación posglacial y su relación con el ascenso relativo del nivel del mar en el extremo este del canal Beagle, Tierra del Fuego, Argentina
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比格犬，火地岛，阿根廷
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发表时间：
2014
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通讯作者：
Masaaki Okuda
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作者：
A. M. Borromei;J. F. Ponce;A. Coronato;M. Candel;D. Olivera;Masaaki Okuda
本文利用数字地形模型、冰后海平面曲线和花粉分析，重建了位于比格尔海峡东部Punta护城河（Moat-2; 54°58′50”S, 66°44′10”W; 40 m s.n.m）的Donatia-Astelia缓冲沼泽从末次盛冰期（LGM，约25 ka cal AP）到全新世中期的海岸线演变和植被。比格尔海峡东口植物群落的演变与火地岛以南无冰地区的区域性冰期后植被格局基本一致。冰期后植被的区域格局为草原，其次为森林-草原，最后为闭林针叶林。早在17700 calyr BP之前，在蓬塔护河目前研究区域的比格尔海峡开始消冰，高山古冰川移至卢西奥洛佩兹山脉山谷和漩涡的源头，导致冲积平原的形成，河流垂直于现在的河道。在全新世早期（11,500-8,000 cal yr BP），植被与比格尔海峡西部和中部的植被相似。然而，海平面相对上升和海洋喷雾湿度的影响有利于蓬塔护城河Nothofagus林的早期发育。到公元前9500年，地貌呈现出封闭森林的面貌。泥炭沼泽则主要为泥炭沼-垫层植物混合类型，具有麦哲伦沼地的植物区系元素特征，这主要是由于与河道开放相吻合的海水喷淋矿物输入以及皮克顿和纽瓦岛的形成。大约在距今7000年左右，麦哲伦荒原和亚南极常绿森林在海岸线构造与今天相似的时候发展起来。
The coast-line evolution and vegetation from the Last Glacial Maximum (LGM, ca. 25 ka cal AP) until the middle Holocene are reconstructed from a digital terrain model and a postglacial sea level curve and pollen analysis of a Donatia-Astelia cushion bog located in Punta Moat (Moat-2; 54°58’50’’S, 66°44’10’’W; 40 m s.n.m.), east Beagle Channel. The evolution of plant communities at eastern mouth of the Beagle Channel is broadly in line with the regional postglacial vegetation pattern in areas devoid of ice south of Tierra del Fuego. The regional pattern of postglacial vegetation shows steppe followed by forest-steppe and closed Nothofagus forest. Prior 17,700 cal yr BP, the onset of deglaciation in the Beagle Channel in the current study area of Punta Moat and, the removal of alpine paleoglaciers to the headwaters of the valleys and cirques of Sierra Lucio Lopez, led the formation of an alluvial plain with streams flowing in a perpendicular direction to the current channel. During the early Holocene (11,500-8,000 cal yr BP), the vegetation was similar to that developed in the western and central sectors of the Beagle Channel. However, the influence of the relative rise of the sea-level and the marine spray-humidity favored the early development of Nothofagus forest in Punta Moat. By 9,500 cal yr BP the landscape showed the physiognomy of a closed forest. Meanwhile on the peat bog, the Sphagnum-cushion plant mixed type prevailed, including floristic elements characteristics of the Magellanic Moorland, due to mineral input from sea spray in coincidence with the opening of channels and the Picton and Nueva islands formation. Towards the ca. 7,000 cal yr BP, the Magellanic Moorland and the Subantarctic Evergreen Forest developed when the coast-line configuration was similar than today.