Late Glacial and Holocene changes in vegetation cover and climate in southern Siberia derived from a 15 kyr long pollen record from Lake Kotokel

Abstract

Abstract. In this study a radiocarbon-dated pollen record from Lake Kotokel (52 • 47 N, 108 • 07 E, 458 m a.s.l.) located in southern Siberia east of Lake Baikal was used to derive quantitative characteristics of regional vegetation and climate from about 15 kyr BP (1 kyr=1000 cal. yr) until today. Quantitative reconstruction of the late glacial vegetation and climate dynamics suggests that open steppe and tundra communities predominated in the study area prior to ca. 13.5 kyr BP and again during the Younger Dryas interval, between 12.8 and 11.6 kyr BP. The pollen-based climate reconstruction suggests lower-than-present mean January (∼−38 • C) and July (∼12 • C) temperatures and annual precipitation (∼270-300 mm) values during these time intervals. Boreal woodland replaced the primarily open landscape around Kotokel three times at about 14.8-14.7 kyr BP, during the Allerød Interstadial between 13.3-12.8 kyr BP and with the onset of the Holocene interglacial between 11.5 and 10.5 kyr BP, presumably in response to a noticeable increase in precipitation, and in July and January temperatures. The maximal spread of the boreal forest (taiga) communities in the region is associated with a warmer and wetter-than-present climate (T w ∼17-18 • C, T c ∼−19 • C, P ann ∼500-550 mm) that occurred ca. 10.8-7.3 kyr BP. During this time interval woody vegetation covered more than 50% of the area within a 21×21 km window around the lake. The pollen-based best modern analogue reconstruction suggests a decrease in woody cover percentages and in all cliCorrespondence to: P. E. Tarasov (ptarasov@zedat.fu-berlin.de) matic variables about 7-6.5 kyr BP. Our results demonstrate a gradual decrease in precipitation and mean January temperature towards their present-day values in the region around Lake Kotokel since that time.

Holocene climate conditions in central Yakutia (Eastern Siberia) inferred from sediment composition and fossil chironomids of Lake Temje

“…the transfer functions) are established. There are few examples of quantitative palaeoclimate reconstructions in Siberia, and those are mainly from pollen studies Müller et al, 2009;Andreev et al, 2011;Tarasov et al, 1999Tarasov et al, , 2009). To date, there is only one quantitative temperature reconstruction inferred from aquatic diatoms in central Siberia (Kumke et al, 2004).…”

Extensive glaciation in Transbaikalia, Siberia, at the Last Glacial Maximum

“…If the large spread in 10Be concentrations resulted from widespread and varied nuclide inheritance (despite this being rather uncommon; Heyman et al, 2011), then the youngest age for each deposit would be the more reliable as it would contain the lowest proportion of inheritance and therefore a minimum age model would be most appropriate. However, in that case, half of the sampled moraines would be of mid-Holocene age, which is highly implausible considering the available information on past climate and glacial chronologies from the wider region (Mackay, 2007;Shichi et al, 2009;Tarasov et al, 2009;Arzhannikov et al, 2012). 15 Alternatively, we infer that processes causing age underestimation have affected some of our samples.…”

“…This period was not only colder but also drier than the preceding OIS-3 (Prokopenko et al, 2001;Mackay, 2007). Cold conditions remained until at least 14.5 ka (Shichi et al, 2009), followed by warmer and possibly wetter than present-day conditions at 14-13 ka (Shichi et al, 2009;Tarasov et al, 2009). Cooling then returned between 12.8 and 11.6 ka, during the Younger Dryas Chronozone (Mackay, 2007;Shichi et al, 2009;Tarasov et al, 2009).…”

“…Notwithstanding Mackay's (2007, p. 198) view that "the transition from the end of the last glacial into the Holocene (Termination 1) was rapid in Lake Baikal (only c. 4 ka)", climate reconstructions elsewhere indicate that conditions remained cold until ~14.5 ka, then cooled again after warming briefly at 14.5-13 ka, coincident with the B0lling-Aller0d interstadial (Shichi et al, 2009;Tarasov et al, 2009). Unfortunately, the large spread in our moraine boulder exposure ages makes it difficult to provide a reliable conclusion on the presence of a Late Glacial ice re-advance in the study area.…”

“…First, the study area lies within zones of continuous and discontinuous permafrost (Maurer, 2007); hence, permafrost dynamics have quite possibly contributed to post-depositional disturbance throughout the Late Glacial and Holocene. Moreover, the moraines might have been ice-cored (and possibly still are) and the buried ice may have experienced melting during the warmer-than-present climate of the early Holocene (Tarasov et al, 2009) resulting in alteration of the moraine morphology. Second, the existence of a temporary glacial lake has been documented in the Chara Depression (Enikeev, 2008(Enikeev, , 2009.…”