A CONTINUOUS LATE-GLACIAL AND HOLOCENE RECORD OF VEGETATION CHANGES IN KAZAKSTAN

The Late Glacial and Holocene vegetation history of northern Kazakhsta n is reconstructed using a well dated continuous pollen record from Oz erki swamp (50 degrees 24'N, 80 degrees 28'E, altitude 210 m), near Se mipalatinsk. A montane steppe-taiga community (Chenopodiaceae, Artemis ia, Picea, Larix and Betula) dominated in this area between 13,000 and 10,100 yr B.P. At the beginning of the Holocene, Poaceae and Artemisi a dominated the steppe and Picea and Larix disappeared. From 7800 to 7 250 yr B.P. a sharp increase in Betula pollen percentages suggests aff orestation. After 5800 yr B.P., Pinus sylvestris spread through the st eppe zone of Kazakhstan. These changes in vegetation distribution are interpreted in terms of changing absolute winter temperatures due to o rbitally induced insolation changes. The absence of boreal conifers du ring the early Holocene can be explained by absolute minimum temperatu res below -60 degrees C, or 8 degrees C colder than today. (C) 1997 El sevier Science B.V.