Two Late Quaternary Pollen Records from South-Central Alaska
Two Late Quaternary Pollen Records from South-Central Alaska
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阿拉斯加中南部的两个晚第四纪花粉记录
DOI：
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发表时间：
2007
期刊：
影响因子：
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通讯作者：
P. Colinvaux
中科院分区：
文献类型：
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作者：
P. Anderson;A. Lozhkin;W. Eisner;M. Kozhevnikova;D. Hopkins;L. Brubaker;P. Colinvaux
来自Wonder湖和Ten Mile湖的花粉记录，分别位于阿拉斯加山脉北部和南部的垂直林木线上，记录了阿拉斯加南部北方森林的一部分植被历史。新的花粉图显示了桦树灌木冻土带，在奇迹湖之前是稀疏的草本冻土带，这是威斯康星州最近时期这两个地区的特征。大约10000年前，杨树在十里湖附近出现，但在Wonder湖显然不存在。青云杉在9100年前生长在十英里湖附近，而马里亚纳在7000年前变得重要。奇迹湖的第一批森林也以青花假单胞树为主，随后是马里亚纳假单胞树的数量增加。由于放射性碳测年的问题，Wonder湖森林形成的时间是不确定的。在大约7000年前，桤木似乎在这两个地区都很常见。这些记录表明，阿拉斯加南部的古植被重建比北部的北方森林更困难，因为地形多样性更大，一些花粉分类群的过度代表性困难，以及放射性碳定年的问题。尽管存在这些担忧，但来自阿拉斯加中南部的现有数据表明，南部和北部森林的植被历史不同。当这些差异与全新世的温度波动有关时，就意味着阿拉斯加北方森林可能不会对未来的全球变暖做出一致的反应。
Pollen records from Wonder and Ten Mile lakes, located at aititudinal treeline to the north and south of the Alaska Range respectively, document the vegetation history of a portion of the southern Alaskan boreal forest. The new pollen diagrams indicate a Betula shrub tundra, preceded at Wonder Lake by a sparse herb tundra, which characterized these two areas during latest Wisconsinan times. Populus was in the vicinity of Ten Mile Lake ca. 10,000 BP, but was apparently absent from Wonder Lake. Picea glauca grew at or near Ten Mile Lake by 9100 BP, with P. mariana becoming important ca. 7000 BP. The first forests at Wonder Lake were also dominated by P. glauca and followed by increased numbers of P. mariana. The timing of forest establishment at Wonder Lake is uncertain due to problematic radiocarbon dates. Alnus appears to be common in both regions by ca. 7000 BP. These records suggest that paleo-vegetational reconstructions are more difficult for the southern than northern boreal forests in Alaska because of greater topographic diversity, difficulties with over-representation of some pollen taxa, and problems with radiocarbon dating. Despite these concerns, available data from south-central Alaska suggest that southern and northern forests differ in their vegetational histories. Such differences, when related to temperature fluctuations that have been postulated for the Holocene, imply that the Alaskan boreal forest may not respond uniformly to future global warming.