A continuous Late Glacial and Holocene record of vegetation changes in Kazakhstan
The Late Glacial and Holocene vegetation history of northern Kazakhstan is reconstructed using a well dated continuous pollen record from Ozerki swamp (50 degrees 24'N, 80 degrees 28'E, altitude 210 m), near Semipalatinsk. A montane steppe-taiga community (Chenopodiaceae, Artemisia, 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 Artemisia dominated the steppe and Picea and Larix disappeared. From 7800 to 7250 yr B.P. a sharp increase in Betula pollen percentages suggests afforestation. After 5800 yr B.P., Pinus sylvestris spread through the steppe zone of Kazakhstan. These changes in vegetation distribution are interpreted in terms of changing absolute winter temperatures due to orbitally induced insolation changes. The absence of boreal conifers during the early Holocene can be explained by absolute minimum temperatures below -60 degrees C, or 8 degrees C colder than today. (C) 1997 Elsevier Science B.V.