Last glacial maximum biomes reconstructed from pollen and plant macrofossil data from northern Eurasia
Résumé
Pollen and plant macrofossil data from northern Eurasia were used to reconstruct the vegetation of the last glacial maximum (LGM: 18,000 +/- 2000 C-14 yr BP) using an objective quantitative method for interpreting pollen data in terms of the biomes they represent (Prentice Et al., 1996). The results confirm previous qualitative vegetation reconstructions at the LGM but provide a more comprehensive analysis of the data. Tundra dominated a large area of northern Eurasia (north of 57 degreesN) to the west, south and east of the Scandinavian ice sheet at the LGM. Steppe-like vegetation was reconstructed in the latitudinal band from western Ukraine, where temperate deciduous forests grow today, to western Siberia, where taiga and cold deciduous forests grow today. The reconstruction shows that steppe graded into tundra in Siberia, which is not the case today. Taiga grew on the northern coast of the Sea of Azov, about 1500 km south of its present limit in European Russia. In contrast, taiga was reconstructed only slightly south of its southern limit today in south-western Siberia. Broadleaved trees were confined to small refuges, e.g. on the eastern coast of the Black Sea, where cool mixed forest was reconstructed from the LGM data. Cool conifer forests in western Georgia were reconstructed as growing more than 1000 m lower than they grow today. The few scattered sites with LGM data from the Tien-Shan Mountains and from northern Mongolia yielded biome reconstructions of steppe and taiga, which are the biomes growing there today.