Late Glacial to Holocene environments in the present-day coldest region of the Northern Hemisphere inferred from a pollen record of Lake Billyakh, Verkhoyansk Mts, NE Siberia
Late Glacial to Holocene environments in the present-day coldest region of the Northern Hemisphere inferred from a pollen record of Lake Billyakh, Verkhoyansk Mts, NE Siberia
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根据西伯利亚东北部韦尔霍扬斯克山比利亚赫湖的花粉记录推断出当今北半球最冷地区的晚冰期至全新世环境
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发表时间：
2008
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通讯作者：
B. Diekmann
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作者：
S. Müller;P. Tarasov;Andrei A. Andreev;B. Diekmann
摘要。本研究利用Verkhoyansk山脉Billyakh湖（65°17′N, 126°47′E, 340 m a.s.l）的放射性碳定年花粉记录，重建了大约15 kyr BP以来的植被和气候变化。花粉记录和基于花粉的生物群系重建表明，在15 ~ 13.5 kyr BP期间，该地区以禾本科、莎草科、蒿科、藜科、石竹科和卷柏属为主的开放式冷草原（STEP）和草莎草苔原（TUND）为主。另一方面，落叶松花粉的持续存在与今天的值相当，表明晚冰期区域植被中持续存在北方落叶针叶树（CLDE）。包括桦树（桦节）、桤木（Duschekia fruticosa）和柳树（Salix）在内的灌丛苔原群落的主要分布年代为13.5-12.7 kyr BP，表明末次冰期末期降水显著增加，特别是在Bolling-Allerod间冰期。在12.7 ~ 11.4 kyr BP之间，草本类群的花粉百分比迅速增加，而灌木类群的花粉百分比下降，表明与相对寒冷和干燥的新仙女木期相关的草原群落加强。然而，已有的花粉资料表明，新仙女木期的气候比早前15 ~ 13.5 kyr BP的气候要温和。在花粉记录中，全新世的开始表现为灌木类群的最高值和草本类群的最低值，表明在11.4 kyr BP之后恢复了温暖和湿润的环境。树木类群百分比逐渐增加，在7 kyr BP后达到最大值，反映了该地区北方寒带落叶林和针叶林的扩散。值得注意的是，苏格兰松（Pinus亚属）的最高百分比在7至2千英呎之间。云杉（Picea）和冷杉（Abies）花粉，表明全新世中期北方森林群落的扩展是对气候改善和多年冻土层退化的响应。
Abstract. In this study, a radiocarbon-dated pollen record from Lake Billyakh (65°17' N, 126°47' E; 340 m a.s.l.) in the Verkhoyansk Mountains was used to reconstruct vegetation and climate change since about 15 kyr BP. The pollen record and pollen-based biome reconstruction suggest that open cool steppe (STEP) and grass and sedge tundra (TUND) communities with Poaceae, Cyperaceae, Artemisia, Chenopodiaceae, Caryophyllaceae and Selaginella rupestris dominated the area from 15 to 13.5 kyr BP. On the other hand, the constant presence of Larix pollen in quantities comparable to today's values points to the constant presence of boreal deciduous conifer (CLDE) trees in the regional vegetation during the Late Glacial. A major spread of shrub tundra communities, including birch (Betula sect. Nanae), alder (Duschekia fruticosa) and willow (Salix) species, is dated to 13.5–12.7 kyr BP, indicating a noticeable increase in precipitation toward the end of the Last Glaciation, particularly during the Bolling-Allerod Interstadial. Between 12.7 and 11.4 kyr BP pollen percentages of herbaceous taxa rapidly increased, whereas shrub taxa percentages decreased, suggesting strengthening of the steppe communities associated with the relatively cold and dry Younger Dryas Stadial. However, the pollen data in hand indicate that Younger Dryas climate was less severe than the climate during the earlier interval from 15 to 13.5 kyr BP. The onset of the Holocene is marked in the pollen record by the highest values of shrub and lowest values of herbaceous taxa, suggesting a return of warmer and wetter conditions after 11.4 kyr BP. Percentages of tree taxa increase gradually and reach maximum values after 7 kyr BP, reflecting the spread of boreal cold deciduous and taiga forests in the region. An interval between 7 and 2 kyr BP is noticeable for the highest percentages of Scots pine (Pinus subgen. Diploxylon), spruce (Picea) and fir (Abies) pollen, indicating mid-Holocene spread of boreal forest communities in response to climate amelioration and degradation of the permafrost layer.