Last glacial vegetation reconstructions in the extreme-continental eastern Asia: Potentials of pollen and n-alkane biomarker analyses Pavel E. Tarasov a, * , Stefanie Müller a , Michael Zech b , Darima Andreeva c , Bernhard Diekmann d , Christian Leipe a a Institute of Geological Sciences, Palaeontology, Free University Berlin, Malteserstraße 74-100, Building D, 12249 Berlin, Germany b Chair of Geomorphology and Department of Soil Physics, University of Bayreuth, Universitätsstraße 30, 95440 Bayreuth, Germany c Institute of General and Experimental Biology, Siberian Branch of the Russian Academy of Sciences, Sakhyanova St. 6, 670047 Ulan-Ude, Russian Federation d Alfred Wegener Institute for Polar and Marine Research, Research Unit Potsdam, Telegrafenberg A43,14473 Potsdam, Germany article info Article history: Available online 13 April 2012 abstract The current study presents quantitative reconstructions of tree cover, annual precipitation and mean July temperature derived from the pollen record from Lake Billyakh (65  17 0 N, 126  47 0 E, 340 m above sea level) spanning the last ca. 50 ka (ca. 50,000 cal yrs). The reconstruction of tree cover suggests presence of woody plants through the entire analyzed time interval, although trees played only a minor role in the vegetation around Lake Billyakh prior to 14 ka BP (<5%). This result corroborates low percentages of tree pollen and low scores of the cold deciduous forest biome in the PG1755 record from Lake Billyakh. The reconstructed values of the mean temperature of the warmest month w8e10  C do not support larch forest or woodland around Lake Billyakh during the coldest phase of the last glacial between w32 and w15 ka BP. However, modern cases from northern Siberia, ca. 750 km north of Lake Billyakh, demon- strate that individual larch plants can grow within shrub and grass tundra landscape in very low mean July temperatures of about 8  C. This makes plausible the hypothesis that the western and southern foreland of the Verkhoyansk Mountains could provide enough moist and warm microhabitats and allow individual larch specimens to survive climatic extremes of the last glacial. Reconstructed mean values of annual precipitation are about 270 mm during the last glacial interval. This value is almost 100 mm higher than modern averages reported for the extreme-continental north-eastern Siberia east of Lake Billyakh, where larch-dominated cold deciduous forest grows at present. This suggests that last glacial environments around Lake Billyakh were never too dry for larch to grow and that the insufficient summer warmth was the main factor, which limited tree growth during the last glacial interval. The n- alkane analysis of the Siberian plants presented in this study demonstrates rather complex alkane distribution patterns, which challenge the interpretation of the fossil records. In particular, extremely low n-alkane concentrations in the leaves of local coniferous trees and shrubs suggest that their contribution to the litter and therefore to the fossil lake sediments might be not high enough for tracing the Quaternary history of the needleleaved taxa using the n-alkane biomarker method. Ó 2012 Elsevier Ltd and INQUA. All rights reserved. 1. Introduction Knowledge of past changes in vegetation serves for a better understanding of archaeological data (e.g. Dolukhanov et al., 2002; Tarasov et al., 2007a), the earth climate system and carbon cycle (e.g. Prentice et al., 1992; Kleinen et al., 2011) and genetic diversity (Semerikov et al., 1999; Petit et al., 2008), and can help to build up current predictions and conservation strategies. The need for accurate vegetation cover datasets is particularly acute for the last glacialeinterglacial interval, given the critical role of surface- atmosphere feedbacks on regional climate dynamics and global biogeochemical cycles (Williams et al., 2011). However, the current knowledge about last glacial vegetation in many regions of the world is limited due to the lack or scarcity of palaeobotanical records (e.g. Prentice et al., 2000). The poor spatial coverage and dating control of the available records may lead to contradicting interpretations of the composition and density of glacial vegetation cover, and of the last glacial climate and environments. All mentioned problems are well pronounced in continental Asia (including vast areas of Siberia), which was not covered with ice * Corresponding author. E-mail addresses: ptarasov@zedat.fu-berlin.de, paveltarasov@mail.ru (P.E. Tarasov). Contents lists available at SciVerse ScienceDirect Quaternary International journal homepage: www.elsevier.com/locate/quaint 1040-6182/$ e see front matter Ó 2012 Elsevier Ltd and INQUA. All rights reserved. doi:10.1016/j.quaint.2012.04.007 Quaternary International 290-291 (2013) 253e263