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Fig. 5.22 A proposed division of the Holocene into three stages based on climatic data in relation to the dynamics of the polar treeline on the Yamal Peninsula in Siberia. The graph illustrates the relative distance of sampled tree remains from the present position of the most northerly open stands of larch in river valleys and the number of tree samples for each radiocarbon date. (Diagram based on data from Hantemirov & Shiatov, 1999, and reproduced with permission from Juday, 2005.)

Fig. 5.23 Tree survival along river courses at the tundra-taiga boundary in the western Siberian Lowlands. (Photo I. A. Brown, reproduced with permission from Callaghan et al., 2002.)

persistence of permafrost. The open cold water in summer in the coastal areas of northern Siberia creates over the region a cold air with high humidity that dominates the present lowland Siberian tundra, with its excessively wet and treeless terrain supporting only an impoverished flora and fauna (Sher, 1996). In such an environment any advance of tree vegetation is limited to better-drained sites along river banks (Fig. 5.23).

Distance (km) Number of trees

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