TY - JOUR A1 - Heinecke, Liv A1 - Epp, Laura Saskia A1 - Reschke, Maria A1 - Stoof-Leichsenring, Kathleen Rosemarie A1 - Mischke, Steffen A1 - Plessen, Birgit A1 - Herzschuh, Ulrike T1 - Aquatic macrophyte dynamics in Lake Karakul (Eastern Pamir) over the last 29 cal ka revealed by sedimentary ancient DNA and geochemical analyses of macrofossil remains JF - Journal of paleolimnolog KW - Potamogeton/Stuckenia KW - Arid central Asia KW - Paleo-productivity KW - Submerged vegetation composition KW - Metabarcoding KW - Chara/Characeae Y1 - 2017 U6 - https://doi.org/10.1007/s10933-017-9986-7 SN - 0921-2728 SN - 1573-0417 VL - 58 SP - 403 EP - 417 PB - Springer CY - Dordrecht ER - TY - JOUR A1 - Fohlmeister, Jens Bernd A1 - Plessen, Birgit A1 - Dudashvili, Alexey Sergeevich A1 - Tjallingii, Rik A1 - Wolff, Christian Michael A1 - Gafurov, Abror A1 - Cheng, Hai T1 - Winter precipitation changes during the Medieval Climate Anomaly and the Little Ice Age in arid Central Asia JF - Quaternary science reviews : the international multidisciplinary research and review journal N2 - The strength of the North Atlantic Oscillation (NAO) is considered to be the main driver of climate changes over the European and western Asian continents throughout the last millennium. For example, the predominantly warm Medieval Climate Anomaly (MCA) and the following cold period of the Little Ice Age (LIA) over Europe have been associated with long-lasting phases with a positive and negative NAO index. Its climatic imprint is especially pronounced in European winter seasons. However, little is known about the influence of NAO with respect to its eastern extent over the Eurasian continent. Here we present speleothem records (PC, 8180 and Sr/Ca) from the southern rim of Fergana Basin (Central Asia) revealing annually resolved past climate variations during the last millennium. The age control of the stalagmite relies on radiocarbon dating as large amounts of detrital material inhibit accurate 230Th dating. Present-day calcification of the stalagmite is most effective during spring when the cave atmosphere and elevated water supply by snow melting and high amount of spring precipitation provide optimal conditions. Seasonal precipitation variations cause changes of the stable isotope and Sr/ Ca compositions. The simultaneous changes in these geochemical proxies, however, give also evidence for fractionation processes in the cave. By disentangling both processes, we demonstrate that the amount of winter precipitation during the MCA was generally higher than during the LIA, which is in line with climatic changes linked to the NAO index but opposite to the higher mountain records of Central Asia. Several events of strongly reduced winter precipitation are observed during the LIA in Central Asia. These dry winter events can be related to phases of a strong negative NAO index and all results reveal that winter precipitation over the central Eurasian continent is tightly linked to atmospheric NAO modes by the westerly wind systems. (C) 2017 Elsevier Ltd. All rights reserved. Y1 - 2017 U6 - https://doi.org/10.1016/j.quascirev.2017.10.026 SN - 0277-3791 VL - 178 SP - 24 EP - 36 PB - Elsevier CY - Oxford ER - TY - GEN A1 - Lauterbach, Stefan A1 - Witt, Roman A1 - Plessen, Birgit A1 - Dulski, Peter A1 - Prasad, Sushma A1 - Mingram, Jens A1 - Gleixner, Gerd A1 - Hettler-Riedel, Sabine A1 - Stebich, Martina A1 - Schnetger, Bernhard A1 - Schwalb, Antje A1 - Schwarz, Anja T1 - Climatic imprint of the mid-latitude Westerlies in the Central Tian Shan of Kyrgyzstan and teleconnections to North Atlantic climate variability during the last 6000 years N2 - In general, a moderate drying trend is observed in mid-latitude arid Central Asia since the Mid-Holocene, attributed to the progressively weakening influence of the mid-latitude Westerlies on regional climate. However, as the spatio-temporal pattern of this development and the underlying climatic mechanisms are yet not fully understood, new high-resolution paleoclimate records from this region are needed. Within this study, a sediment core from Lake Son Kol (Central Kyrgyzstan) was investigated using sedimentological, (bio) geochemical, isotopic, and palynological analyses, aiming at reconstructing regional climate development during the last 6000 years. Biogeochemical data, mainly reflecting summer moisture conditions, indicate predominantly wet conditions until 4950 cal. yr BP, succeeded by a pronounced dry interval between 4950 and 3900 cal. yr BP. In the following, a return to wet conditions and a subsequent moderate drying trend until present times are observed. This is consistent with other regional paleoclimate records and likely reflects the gradual Late Holocene diminishment of the amount of summer moisture provided by the mid-latitude Westerlies. However, climate impact of the Westerlies was apparently not only restricted to the summer season but also significant during winter as indicated by recurrent episodes of enhanced allochthonous input through snowmelt, occurring before 6000 cal. yr BP and at 5100-4350, 3450-2850, and 1900-1500 cal. yr BP. The distinct similar to 1500year periodicity of these episodes of increased winter precipitation in Central Kyrgyzstan resembles similar cyclicities observed in paleoclimate records around the North Atlantic, likely indicating a hemispheric-scale climatic teleconnection and an impact of North Atlantic Oscillation (NAO) variability in Central Asia. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 408 KW - Central Asia KW - climate KW - Holocene KW - lake sediments KW - mid-latitude Westerlies KW - NAO Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-404085 ER - TY - JOUR A1 - Heinecke, Liv A1 - Mischke, Steffen A1 - Adler, Karsten A1 - Barth, Anja A1 - Biskaborn, Boris A1 - Plessen, Birgit A1 - Nitze, Ingmar A1 - Kuhn, Gerhard A1 - Rajabov, Ilhomjon A1 - Herzschuh, Ulrike T1 - Climatic and limnological changes at Lake Karakul (Tajikistan) during the last similar to 29 cal ka JF - Journal of paleolimnolog N2 - We present results of analyses on a sediment core from Lake Karakul, located in the eastern Pamir Mountains, Tajikistan. The core spans the last similar to 29 cal ka. We investigated and assessed processes internal and external to the lake to infer changes in past moisture availability. Among the variables used to infer lake-external processes, high values of grain-size end-member (EM) 3 (wide grain-size distribution that reflects fluvial input) and high Sr/Rb and Zr/Rb ratios (coinciding with coarse grain sizes), are indicative of moister conditions. High values in EM1, EM2 (peaks of small grain sizes that reflect long-distance dust transport or fine, glacially derived clastic input) and TiO2 (terrigenous input) are thought to reflect greater influence of dry air masses, most likely of Westerly origin. High input of dust from distant sources, beginning before the Last Glacial Maximum (LGM) and continuing to the late glacial, reflects the influence of dry Westerlies, whereas peaks in fluvial input suggest increased moisture availability. The early to early-middle Holocene is characterised by coarse mean grain sizes, indicating constant, high fluvial input and moister conditions in the region. A steady increase in terrigenous dust and a decrease in fluvial input from 6.6 cal ka BP onwards points to the Westerlies as the predominant atmospheric circulation through to present, and marks a return to drier and even arid conditions in the area. Proxies for productivity (TOC, TOC/TN, TOCBr), redox potential (Fe/Mn) and changes in the endogenic carbonate precipitation (TIC, delta(18) OCarb) indicate changes within the lake. Low productivity characterised the lake from the late Pleistocene until 6.6 cal ka BP, and increased rapidly afterwards. Lake level remained low until the LGM, but water depth increased to a maximum during the late glacial and remained high into the early Holocene. Subsequently, the water level decreased to its present stage. Today the lake system is mainly climatically controlled, but the depositional regime is also driven by internal limnogeological processes. KW - Arid Central Asia KW - Pamir Mountains KW - Lake sediments KW - XRF data KW - Grain-size end-member modelling KW - Geochemistry Y1 - 2017 U6 - https://doi.org/10.1007/s10933-017-9980-0 SN - 0921-2728 SN - 1573-0417 VL - 58 SP - 317 EP - 334 PB - Springer CY - Dordrecht ER - TY - GEN A1 - Zibulski, Romy A1 - Wesener, Felix A1 - Wilkes, Heinz A1 - Plessen, Birgit A1 - Pestryakova, Luidmila Agafyevna A1 - Herzschuh, Ulrike T1 - C / N ratio, stable isotope (δ 13 C, δ 15 N), and n-alkane patterns of brown mosses along hydrological gradients of low-centred polygons of the Siberian Arctic T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - Mosses are a major component of the arctic vegetation, particularly in wetlands. We present C / N atomic ratio, delta C-13 and delta N-15 data of 400 brown-moss samples belonging to 10 species that were collected along hydrological gradients within polygonal mires located on the southern Taymyr Peninsula and the Lena River delta in northern Siberia. Additionally, n-alkane patterns of six of these species (16 samples) were investigated. The aim of the study is to see whether the inter-and intraspecific differences in C / N, isotopic compositions and n-alkanes are indicative of habitat, particularly with respect to water level. Overall, we find high variability in all investigated parameters for two different moisture-related groups of moss species. The C / N ratios range between 11 and 53 (median: 32) and show large variations at the intraspecific level. However, species preferring a dry habitat (xero-mesophilic mosses) show higher C / N ratios than those preferring a wet habitat (meso-hygrophilic mosses). The delta C-13 values range between 37.0 and 22.5% (median D 27.8 %). The delta N-15 values range between 6.6 and C 1.7%(median D 2.2 %). We find differences in delta C-13 and delta N-15 compositions between both habitat types. For some species of the meso-hygrophilic group, we suggest that a relationship between the individ-ual habitat water level and isotopic composition can be inferred as a function of microbial symbiosis. The n-alkane distribution also shows differences primarily between xeromesophilic and meso-hygrophilic mosses, i. e. having a dominance of n-alkanes with long (n-C29, n-C31 /and intermediate (n-C25 /chain lengths, respectively. Overall, our results reveal that C / N ratios, isotopic signals and n-alkanes of studied brown-moss taxa from polygonal wetlands are characteristic of their habitat. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 672 KW - atmospheric nitrogen deposition KW - Lena River delta KW - free amino-acids KW - ombrotrophic peat KW - carbon isotopes KW - aquatic macrophytes KW - methane oxidation KW - organic matter KW - soil-nitrogen KW - plants Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-417104 SN - 1866-8372 IS - 672 ER - TY - JOUR A1 - Zibulski, Romy A1 - Wesener, Felix A1 - Wilkes, Heinz A1 - Plessen, Birgit A1 - Pestryakova, Luidmila Agafyevna A1 - Herzschuh, Ulrike T1 - C / N ratio, stable isotope (delta C-13, delta N-15), and n-alkane patterns of brown mosses along hydrological gradients of low-centred polygons of the Siberian Arctic JF - Biogeosciences N2 - Mosses are a major component of the arctic vegetation, particularly in wetlands. We present C / N atomic ratio, delta C-13 and delta N-15 data of 400 brown-moss samples belonging to 10 species that were collected along hydrological gradients within polygonal mires located on the southern Taymyr Peninsula and the Lena River delta in northern Siberia. Additionally, n-alkane patterns of six of these species (16 samples) were investigated. The aim of the study is to see whether the inter-and intraspecific differences in C / N, isotopic compositions and n-alkanes are indicative of habitat, particularly with respect to water level. Overall, we find high variability in all investigated parameters for two different moisture-related groups of moss species. The C / N ratios range between 11 and 53 (median: 32) and show large variations at the intraspecific level. However, species preferring a dry habitat (xero-mesophilic mosses) show higher C / N ratios than those preferring a wet habitat (meso-hygrophilic mosses). The delta C-13 values range between 37.0 and 22.5% (median D 27.8 %). The delta N-15 values range between 6.6 and C 1.7%(median D 2.2 %). We find differences in delta C-13 and delta N-15 compositions between both habitat types. For some species of the meso-hygrophilic group, we suggest that a relationship between the individ-ual habitat water level and isotopic composition can be inferred as a function of microbial symbiosis. The n-alkane distribution also shows differences primarily between xeromesophilic and meso-hygrophilic mosses, i. e. having a dominance of n-alkanes with long (n-C29, n-C31 /and intermediate (n-C25 /chain lengths, respectively. Overall, our results reveal that C / N ratios, isotopic signals and n-alkanes of studied brown-moss taxa from polygonal wetlands are characteristic of their habitat. Y1 - 2017 U6 - https://doi.org/10.5194/bg-14-1617-2017 SN - 1726-4170 SN - 1726-4189 VL - 14 SP - 1617 EP - 1630 PB - Copernicus CY - Göttingen ER - TY - JOUR A1 - Lechleitner, Franziska A. A1 - Breitenbach, Sebastian Franz Martin A1 - Cheng, Hai A1 - Plessen, Birgit A1 - Rehfeld, Kira A1 - Goswami, Bedartha A1 - Marwan, Norbert A1 - Eroglu, Deniz A1 - Adkins, Jess F. A1 - Haug, Gerald T1 - Climatic and in-cave influences on delta O-18 and delta C-13 in a stalagmite from northeastern India through the last deglaciation JF - Quaternary research : an interdisciplinary journal N2 - Northeastern (NE) India experiences extraordinarily pronounced seasonal climate, governed by the Indian summer monsoon (ISM). The vulnerability of this region to floods and droughts calls for detailed and highly resolved paleoclimate reconstructions to assess the recurrence rate and driving factors of ISM changes. We use stable oxygen and carbon isotope ratios (delta O-18 and delta C-13) from stalagmite MAW-6 from Mawmluh Cave to infer climate and environmental conditions in NE India over the last deglaciation (16-6ka). We interpret stalagmite delta O-18 as reflecting ISM strength, whereas delta C-13 appears to be driven by local hydroclimate conditions. Pronounced shifts in ISM strength over the deglaciation are apparent from the delta O-18 record, similarly to other records from monsoonal Asia. The ISM is weaker during the late glacial (LG) period and the Younger Dryas, and stronger during the BOlling-Allerod and Holocene. Local conditions inferred from the delta C-13 record appear to have changed less substantially over time, possibly related to the masking effect of changing precipitation seasonality. Time series analysis of the delta O-18 record reveals more chaotic conditions during the late glacial and higher predictability during the Holocene, likely related to the strengthening of the seasonal recurrence of the ISM with the onset of the Holocene. KW - Indian Summer Monsoon KW - stalagmite KW - oxygen isotopes KW - carbon isotopes KW - deglaciation Y1 - 2017 U6 - https://doi.org/10.1017/qua.2017.72 SN - 0033-5894 SN - 1096-0287 VL - 88 SP - 458 EP - 471 PB - Cambridge Univ. Press CY - New York ER -