Postglacial flooding and vegetation history on the Ob River terrace, central Western Siberia based on the palaeoecological record from Lake Svetlenkoye

Abstract

The hemispheric-scale climatic fluctuations during the Holocene have probably influenced the large Siberian rivers. However, detailed studies of the West Siberian Plain postglacial environmental change are scarce and the records of millennial-scale palaeohydrology are nearly absent. This paper presents the Holocene palaeoecological reconstruction based on the sedimentary record of Lake Svetlenkoye, located near the confluence of major Siberian rivers Ob and Irtysh. Postglacial history of flooding, dynamics of regional and local vegetation, sedimentation regime, geochemical changes and lake water pH were reconstructed based on multi-proxy studies. We used palaeobotanical (plant macrofossils, pollen, diatoms), geochemical (organic matter, total organic carbon and nitrogen content, carbon/nitrogen ratio) and chronological (14C dates, spheroidal fly-ash particle counts) methods. The studied sediment section started to accumulate ~11,400 cal. yr BP. The initial shallow water body was flooded by Ob River waters ~8100–8000 cal. yr BP as confirmed by a remarkable increase in the sedimentation rate and the accumulation rate of the aquatic vegetation proxies. The period of flooding coincides with the high humidity periods reconstructed from regional palaeobotanical records. About 6800–6700 cal. yr BP, the study site became isolated from the Ob River floodplain and remained a small lake until present. The diatom-based lake water pH estimates suggest fluctuations in the pH values during the Holocene, the recent decrease since 1960s being the most notable. The vegetation record revealed constant postglacial presence of tree taxa – Betula, Pinus and Picea – although in different pollen ratios and accumulation rates through time. The paludification of the surroundings occurred since ca. 8500 cal. yr BP.

Multi‐proxy climate and environmental records from a Holocene eutrophic mire, southern taiga subzone, West Siberia

“…The record of mire development in S-2 has strong similarities in mire development to other records in the taiga and arctic zones of West Siberia that cover the Middle and Late Holocene (Velichko et al 1997;Andreev et al 2003;Blyakharchuk 2009;Amon et al 2020;Fig. 6), indicating that the record has been influenced predominantly by (regional) climatic fluctuations, and that local, autogenous processes play a minor role.…”

“…2011); 9 = lake (Amon et al . 2020); 10 = lake (Biskaborn et al . 2016); 11 = two tributaries of the Yenisei River (Sidorchuk et al .…”

“…a BP (Borisova et al 2011), in the middle taiga of West Siberia at 8100 to 6800 cal. a BP (Amon et al 2020), in the south of East Siberia at 6800 to 6600 cal. a BP (Sidorchuk et al 2003 andVorobyeva et al 1992 therein) and in the north of East Siberia at 9000 to 4000 cal.…”

“…We tentatively interpret progressive drying of the mire surface as a consequence of a decrease in precipitation continuing after the Holocene thermal optimum. Dry climate conditions in the Late Holocene have been recorded more widely in peatlands and lake sediments of the taiga and arctic zones in West Siberia (Velichko et al 1997;Andreev et al 2003;Blyakharchuk 2009;Amon et al 2020;Fig. 6).…”

The main physical and geographical characteristics of the Mukhrino field station area and its surroundings

“…При изучении физико-химических свойств болотного комплекса были освещены гео-и биохимические [Степанова, Покровский, 2011;Латыш, 2017;Szajdak et al 2019], гидрологические [Bleuten et al, 2020] и метеорологические [Dyukarev et al, 2021] характеристики торфяной толщи. Исследования биологических свойств были связаны с изучением потоков парниковых газов [Alekseychik et al 2017;Glagolev et al 2018;Dyukarev et al, 2018], палеоэкологии болот [Amon et al, 2020], микробиологии, включая микологию [Белова и др., 2013;Filippova, 2019], инвентаризации флоры лишайников [Лапшина и Конева, 2010], мхов и сосудистых растений [Лапшина, Писаренко, 2013], а также орнитофауны [Архипов и др., 2018].…”