Changes in annual precipitation in the younger dryas and Holocene in Southwestern Siberia

The article presents the results of numerical reconstruction of annual precipitation (PANN, mm/yr) in the Holocene and Younger Dryas (YD) based on the pollen data from bottom sediments of two lakes (Maloye Yarovoe and Kuchuk) in the Kulunda Depression in Southwestern Siberia. Precipitation was reconstructed using the transfer function calibrated on the database of surface pollen spectra. The reconstruction of the YD annual precipitation reveals the mean amount of PANN at 285 mm/yr for Maloe Yarovoye and 322 mm/yr for Kuchuk. The average PANN values calculated for the Holocene were 340 and 364 mm/yr, respectively. The mean PANN of the YD from Maloe Yarovoe was 21 % less than the present-day precipitation level. The YD of the Kulunda Depression was distinguished by treeless steppe and semidesert environment with the decreased level of annual precipitation. The Holocene in Kulunda started with rapid increase of tree taxa (Betula, Pinus sylvesris) in pollen spectra. The maximum of Pinaceae (P. sylvestris, P. sibirica, Abies and Picea) with significant contribution of Ulmus occurred between 7500-2600 BP. The PANN values for this interval were 352 mm/ yr for Maloe Yarovoe and 378 mm/yr for Kuchuk. The decrease of the PANN began in the Late Holocene testifying to climate aridization, although not as strong as in the YD.