Stable vegetation and environmental conditions during the Last Glacial Maximum: New results from Lake Kotokel (Lake Baikal region, southern Siberia, Russia)
Stable vegetation and environmental conditions during the Last Glacial Maximum: New results from Lake Kotokel (Lake Baikal region, southern Siberia, Russia)
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DOI：
10.1016/j.quaint.2013.12.012
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发表时间：
2014-10-20
影响因子：
2.2
通讯作者：
Krivonogov, Sergey K.
中科院分区：
文献类型：
--
作者：
Mueller, Stefanie;Tarasov, Pavel E.;Krivonogov, Sergey K.
本文报道了科托凯尔湖（52 ° 47 ' N，108 ° 07 ' E，458 m a.s.l.）并提供了一个重建的末次盛冰期（LGM）植被和环境在研究区在这段时间内，全球恶劣的气候。科托凯尔湖位于贝加尔湖东海岸线附近，位于西伯利亚南部的北方森林区。分析的底部岩芯KTK 10（KTK 10/6）的190 cm长剖面6由致密、未受扰动、绿灰色至深灰色、轻微层状粉质粘土组成，表明在整个末次冰期期间约有连续的湖相沉积。26.8-19.1 cal. kaBP.年龄模型得到了11个校准的AMS日期的支持。花粉分析和基于花粉的生物群系重建结果表明，草原和冻原植被主要由禾本科和草本植物组成。26.8-19.1 cal. ka BP。整个记录中针叶树管胞和气孔的出现，以及少量的北方针叶树和阔叶树和灌木花粉，表明在湖泊附近，最有可能在河谷中存在单棵树或小森林。生物化方法的应用和由此产生的最具特色的生物群落（草原，苔原和寒冷的落叶林）的数值分数显示轻微的波动，标志着稳定的区域植被覆盖在分析的末次盛冰期间隔。与区域生物群落相比，当地环境指标表明湖泊系统对十年和百年尺度气候变率的敏感性更高。代表沿岸的/草甸植被群落的毛茛科花粉百分比最高，登记在ca。23.8-23.4 cal. ka BP。这一点和粗粒砂颗粒的增加以及KTK 10/6沉积物中代表方解石的总无机碳（TIC）值略有增加，证明取芯地点与海岸线之间的距离比目前短得多，湖泊面积减少，符合比目前更干燥的末次冰期气候。研究区草地植被总体稳定。26.8-19.1 cal. ka BP和相对恒定的总有机碳（TOC）值支持这一假设，即这种生产性植被可以稳定地作为大量食草动物的多年生食物资源，从而为当地狩猎采集者在贝加尔湖地区的LGM间隔期间居住的有利环境。(C)2013 Elsevier Ltd和INQUA。All rights reserved.
This paper presents a new decadal-resolution fossil pollen record from Lake Kotokel (52 degrees 47 ' N,108 degrees 07 ' E, 458 m a.s.l.) and provides a reconstruction of the Last Glacial Maximum (LGM) vegetation and environments in the study area during this interval of globally harsh climate. Lake Kotokel is situated close to the eastern shoreline of Lake Baikal, in the boreal forest zone of southern Siberia. The analysed 190 cm long section 6 of the bottom core KTK10 (KTK10/6) consists of compact, undisturbed, greenish-grey to dark-grey, slightly laminated silty clay indicating continuous lacustrine sedimentation throughout the LGM period ca. 26.8-19.1 cal. kaBP. The age model is supported by 11 calibrated AMS dates. The results of pollen analysis and pollen-based biome reconstruction show that steppe and tundra vegetation composed of grasses and various herbs dominated ca. 26.8-19.1 cal. ka BP. Occurrence of conifer tracheids and stomata throughout the record, together with small quantities of boreal conifer and broadleaf tree and shrub taxa pollen, suggests the presence of single trees or small forest stands in the lake vicinity, most likely in the river valleys. Application of the biomisation method and the resulting numerical scores of the most characteristic biomes (steppe, tundra and cold deciduous forest) show minor fluctuations, signifying stability of the regional vegetation cover during the analysed LGM interval. In contrast to the regional biomes, the local environmental indicators demonstrate greater sensitivity of the lake system to decadal- and century-scale climate variability. The highest pollen percentages of Ranunculaceae, representing littoral/meadow vegetation communities, are registered ca. 23.8-23.4 cal. ka BP. This and an increase in coarse-grained sand particles together with slightly increased total inorganic carbon (TIC) values representing calcite in the KTK10/6 sediment provide evidence of a much shorter than present distance between the coring site and the shoreline and a reduced lake area, in line with a drier-than-present LGM climate. A general stability of the grassland vegetation in the study region ca. 26.8-19.1 cal. ka BP and relatively constant total organic carbon (TOC) values support the hypothesis that this productive vegetation could stably serve as a perennial food resource for large populations of herbivores, thus providing favourable environments for the local huntere-gatherers inhabiting the Lake Baikal region during the LGM interval. (C) 2013 Elsevier Ltd and INQUA. All rights reserved.