加拿大育空西南部冻土区一条孢粉剖面及其古环境意义

摘要/Abstract

摘要： 育空西南部多年冻土区一条泥炭剖面的花粉分析资料表明,泥炭花粉谱可以因地貌过程而发生较大变化。受花粉产量悬殊的两个土著群落生态性更替的影响,代表区域性植被面貌的云杉花粉百分含量在后期大幅度降低(但其花粉浓度并未发生明显变化)。这一特点与该区广泛发育的泥炭丘地的形成密切相关,而不代表区域性云杉森林—苔原植被面貌在过去的1230年中曾有明显的改变。因此,在古环境研究中,区分局部性与区域性花粉谱变化有着重要的意义。

关键词: 地层花粉分析, 花粉浓度, 数值分析, 泥炭丘地, 育空

Abstract: Pollen records from peat deposits in the Middle Mackintosh Creek, southwest Yukon Territory, Canada indicate that change of pollen spectra from peat deposits can be caused by the evolution of local environmental condition related to geomorphological process. A significant decrease of Picea pollen percentages in about 20% at the upper part of the pollen diagram has been interpreted as the result of a substitution of shrub birch community for the sedges, because the change of microtopography resulted from the development of a palsa field in the bottom of valley improved the drainage condition, therefore favoured the expansion of shrub birch community which is a heavy pollen producer. Consistent values of Picea pollen concentration support this interpreation. The regional spruce forest-tundra vegetation of the creek has had little change since the eruption of White River ash at 1230 yr B. P. Accordingly, it is important to distinguish the local and regional pollen spectra in terms of the reconstruction of environmental history.

Key words: palynostratigraphy, pollen concentration, numerical analysis, palsa field, Yukon

王夏成. 加拿大育空西南部冻土区一条孢粉剖面及其古环境意义[J]. 冰川冻土, 1989, 11(2): 99-112.

Wang Xiacheng. A Pollen Profile from the Permafrost Region in Southwest Yukon Territory and Its Paleoenvironmental Significance[J]. JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY, 1989, 11(2): 99-112.

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