TY - JOUR A1 - Syrykh, Lydmila S. A1 - Nazarova, Larisa B. A1 - Herzschuh, Ulrike A1 - Subetto, D. A. A1 - Grekov, I. M. T1 - Reconstruction of palaeoecological and palaeoclimatic conditions of the Holocene in the south of the Taimyr according to an analysis of lake sediments JF - Contemporary Problems of Ecology N2 - A sediment core from Khatanga-12 Lake (Taimyr Peninsula, Krasnoyarsk krai) has been studied. The 131.5-cm-long core covers ca. 7100 years of sedimentation. Chironomid analysis, a qualitative reconstruction of the paleoenvironment in the region, and a quantitative reconstruction of variations of the mean July air temperature and in the water depth of the lake have been performed using Northern Russia chironomid-inferred mean July temperature models (Nazarova et al., 2008, 2011, 2015). Khatanga-12 Lake was formed during the Middle Holocene warming as a result of thermokarst processes. The development of the lake ecosystem at different stages of its development was influenced by climatic and cryolithogenic factors. The Middle Holocene warming, which occurred around 7100-6250 cal. years BP, activated thermokarst processes and resulted in the formation of the lake basin. Later, between 6250 and 4500 cal. years BP, a period of cooling took place, as is proved by chironomid analysis. The bottom sediments of the lake during this period were formed by erosion processes on the lake shores. The reconstructed conditions were close to the modern after 2500 cal. years BP. KW - Chironomidae KW - paleolimnology KW - Holocene KW - climate reconstructions KW - Russian Arctic region KW - Khatanga Y1 - 2017 U6 - https://doi.org/10.1134/S1995425517040114 SN - 1995-4255 SN - 1995-4263 VL - 10 SP - 363 EP - 369 PB - Pleiades Publ. CY - New York ER - TY - JOUR A1 - Palagushkina, Olga V. A1 - Wetterich, Sebastian A1 - Schirrmeister, Lutz A1 - Nazarova, Larisa B. T1 - Modern and fossil diatom assemblages from Bol’shoy Lyakhovsky Island (New Siberian Archipelago, Arctic Siberia) JF - Contemporary Problems of Ecology N2 - This article discusses the results of a taxonomic and ecological investigation of diatoms from polygonal ponds and Quaternary permafrost deposits of Bol’shoy Lyakhovsky Island (New Siberian Archipelago) and the reconstruction of climatic changes on the Island during late Pleistocene/Holocene transition using fossil diatom assemblages from the permafrost deposits. The taxonomic list of diatoms includes 159 diatom species. The main ecological factors that determine the distribution of diatoms in the investigated data set are mean July air temperature, рН, electrical conductivity, water depth, and concentrations of Si4+ and Al3+. An increase in water depth and stable lacustrine conditions in the Lateglacial–Holocene in the ancient thermokarst lake relate to Lateglacial warming before 11860 ± 160 years BP and during the early Holocene between 11210 ± 160 and 7095 ± 60 years BP. KW - Pleistocene KW - Holocene Y1 - 2017 U6 - https://doi.org/10.1134/S1995425517040060 SN - 1995-4255 SN - 1995-4263 VL - 10 SP - 380 EP - 394 PB - Pleiades Publ. CY - New York ER - TY - JOUR A1 - Nazarova, Larisa B. A1 - de Hoog, Verena A1 - Hoff, Ulrike A1 - Dirksen, Oleg A1 - Diekmann, Bernhard T1 - Late Holocene climate and environmental changes in Kamchatka inferred from the subfossil chironomid record JF - Quaternary science reviews : the international multidisciplinary research and review journal N2 - This study presents a reconstruction of the Late Holocene climate in Kamchatka based on chironomid remains from a 332 cm long composite sediment core recovered from Dvuyurtochnoe Lake (Two-Yurts Lake, TYL) in central Kamchatka. The oldest recovered sediments date to about 4500 cal years BP. Chironomid head capsules from TYL reflect a rich and diverse fauna. An unknown morphotype of Tanytarsini, Tanytarsus type klein, was found in the lake sediments. Our analysis reveals four chironomid assemblage zones reflecting four different climatic periods in the Late Holocene. Between 4500 and 4000 cal years BP, the chironomid composition indicates a high lake level, well-oxygenated lake water conditions and close to modern temperatures (similar to 13 degrees C). From 4000 to 1000 cal years BP, two consecutive warm intervals were recorded, with the highest reconstructed temperature reaching 16.8 degrees C between 3700 and 2800 cal years BP. Cooling trend, started around 1100 cal years BP led to low temperatures during the last stage of the Holocene. Comparison with other regional studies has shown that termination of cooling at the beginning of late Holocene is relatively synchronous in central Kamchatka, South Kurile, Bering and Japanese Islands and take place around 3700 cal years BP. From ca 3700 cal years BP to the last millennium, a newly strengthened climate continentality accompanied by general warming trend with minor cool excursions led to apparent spatial heterogeneity of climatic patterns in the region. Some timing differences in climatic changes reconstructed from chironomid record of TYL sediments and late Holocene events reconstructed from other sites and other proxies might be linked to differences in local forcing mechanisms or caused by the different degree of dating precision, the different temporal resolution, and the different sensitive responses of climate proxies to the climate variations. Further high-resolution stratigraphic studies in this region are needed to understand the spatially complex pattern of climate change in Holocene in Kamchatka and the surrounding region. KW - Kamchatka KW - Holocene KW - Chironomids KW - Palaeoclimate KW - Temperature Y1 - 2013 U6 - https://doi.org/10.1016/j.quascirev.2013.01.018 SN - 0277-3791 VL - 67 IS - 9 SP - 81 EP - 92 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Zhilich, Snezhana A1 - Rudaya, Natalia A1 - Krivonogov, Sergei A1 - Nazarova, Larisa B. A1 - Pozdnyakov, Dmitry T1 - Environmental dynamics of the Baraba forest-steppe (Siberia) over the last 8000 years and their impact on the types of economic life of the population JF - Quaternary science reviews : the international multidisciplinary research and review journal N2 - This article offers a reconstruction of the vegetation and climate of the south-western Siberian Baraba forest-steppe area during the last ca. 8000 years. The analysis of palynological data from the sediment core of Lake Bolshie Toroki using quantitative methods has made it possible to reconstruct changes of the dominant types of vegetation and mean July air temperatures. Coniferous forests grew in the vicinity of the lake, and mean July air temperatures were similar to present-day ones between 7.9 and 7.0 kyr BP. The warmest and driest climate occurred at 7.0-5.0 kyr BP. At that time, the region had open steppe landscapes; birch groves began to spread. A cooling trend is seen after 5.5 kyr BP, when forest-steppe began to emerge. Steppe communities started to dominate again after 1.5 kyr BP. Mean July air temperatures lower than now are reconstructed for the period of 1.9-1 kyr BP, and then the temperatures became similar to present-day ones. Comparing the archaeological data on the types of economy of the population which inhabited the Baraba forest-steppe with the data on changes in the natural environment revealed a connection between the gradual transition from hunting and fishing to livestock breeding and the development of forest-steppe landscapes with a decrease in the area covered by forests. The development of the forest-steppe as an ecotonic landscape starting around 5 kyr BP might have contributed to the coexistence of several archaeological cultures with different types of economy on the same territory. (C) 2017 Elsevier Ltd. All rights reserved. KW - Holocene KW - Climate dynamics KW - Russia KW - Vegetation dynamics KW - Baraba forest-steppe KW - Archaeology KW - Transfer function Y1 - 2017 U6 - https://doi.org/10.1016/j.quascirev.2017.03.022 SN - 0277-3791 VL - 163 SP - 152 EP - 161 PB - Elsevier CY - Oxford ER -