TY - JOUR A1 - Tian, Fang A1 - Qin, Wen A1 - Zhang, Ran A1 - Herzschuh, Ulrike A1 - Ni, Jian A1 - Zhang, Chengjun A1 - Mischke, Steffen A1 - Cao, Xianyong T1 - Palynological evidence for the temporal stability of the plant community in the Yellow River Source Area over the last 7,400 years JF - Vegetation history and archaeobotany N2 - The terrestrial ecosystem in the Yellow River Source Area (YRSA) is sensitive to climate change and human impacts, although past vegetation change and the degree of human disturbance are still largely unknown. A 170-cm-long sediment core covering the last 7,400 years was collected from Lake Xingxinghai (XXH) in the YRSA. Pollen, together with a series of other environmental proxies (including grain size, total organic carbon (TOC) and carbonate content), were analysed to explore past vegetation and environmental changes for the YRSA. Dominant and common pollen components-Cyperaceae, Poaceae, Artemisia, Chenopodiaceae and Asteraceae-are stable throughout the last 7,400 years. Slight vegetation change is inferred from an increasing trend of Cyperaceae and decreasing trend of Poaceae, suggesting that alpine steppe was replaced by alpine meadow at ca. 3.5 ka cal bp. The vegetation transformation indicates a generally wetter climate during the middle and late Holocene, which is supported by increased amounts of TOC and Pediastrum (representing high water-level) and is consistent with previous past climate records from the north-eastern Tibetan Plateau. Our results find no evidence of human impact on the regional vegetation surrounding XXH, hence we conclude the vegetation change likely reflects the regional climate signal. KW - Pollen KW - Lake Xingxinghai KW - Tibetan Plateau KW - Holocene KW - Vegetation change KW - Regional climate Y1 - 2022 U6 - https://doi.org/10.1007/s00334-022-00870-5 SN - 0939-6314 SN - 1617-6278 VL - 31 IS - 6 SP - 549 EP - 558 PB - Springer CY - New York ER - TY - JOUR A1 - Yuan, Xiaoping P. A1 - Jiao, Ruohong A1 - Dupont-Nivet, Guillaume A1 - Shen, Xiaoming T1 - Southeastern Tibetan Plateau growth revealed by inverse analysis of landscape evolution model JF - Geophysical research letters N2 - The Cenozoic history of the Tibetan Plateau topography is critical for understanding the evolution of the Indian-Eurasian collision, climate, and biodiversity. However, the long-term growth and landscape evolution of the Tibetan Plateau remain ambiguous, it remains unclear if plateau uplift occurred soon after the India-Asia collision in the Paleogene (similar to 50-25 Ma) or later in the Neogene (similar to 20-5 Ma). Here, we reproduce the uplift history of the southeastern Tibetan Plateau using a 2D landscape evolution model, which simultaneously solves fluvial erosion and sediment transport processes in the drainage basins of the Three Rivers region (Yangtze, Mekong, and Salween Rivers). Our model was optimized through a formal inverse analysis with 20,000 forward simulations, which aims to reconcile the transient states of the present-day river profiles. The results, compared to existing paleoelevation and thermochronologic data, suggest initially low elevations (similar to 300-500 m) during the Paleogene, followed by a gradual southeastward propagation of topographic uplift of the plateau margin. KW - Tibetan Plateau KW - landscape evolution KW - fluvial erosion KW - inverse analysis KW - mountain growth KW - propagating uplift Y1 - 2022 U6 - https://doi.org/10.1029/2021GL097623 SN - 0094-8276 SN - 1944-8007 VL - 49 IS - 10 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Jia, Weihan A1 - Anslan, Sten A1 - Chen, Fahu A1 - Cao, Xianyong A1 - Dong, Hailiang A1 - Dulias, Katharina A1 - Gu, Zhengquan A1 - Heinecke, Liv A1 - Jiang, Hongchen A1 - Kruse, Stefan A1 - Kang, Wengang A1 - Li, Kai A1 - Liu, Sisi A1 - Liu, Xingqi A1 - Liu, Ying A1 - Ni, Jian A1 - Schwalb, Antje A1 - Stoof-Leichsenring, Kathleen R. A1 - Shen, Wei A1 - Tian, Fang A1 - Wang, Jing A1 - Wang, Yongbo A1 - Wang, Yucheng A1 - Xu, Hai A1 - Yang, Xiaoyan A1 - Zhang, Dongju A1 - Herzschuh, Ulrike T1 - Sedimentary ancient DNA reveals past ecosystem and biodiversity changes on the Tibetan Plateau: overview and prospects JF - Quaternary science reviews : the international multidisciplinary research and review journal N2 - Alpine ecosystems on the Tibetan Plateau are being threatened by ongoing climate warming and intensified human activities. Ecological time-series obtained from sedimentary ancient DNA (sedaDNA) are essential for understanding past ecosystem and biodiversity dynamics on the Tibetan Plateau and their responses to climate change at a high taxonomic resolution. Hitherto only few but promising studies have been published on this topic. The potential and limitations of using sedaDNA on the Tibetan Plateau are not fully understood. Here, we (i) provide updated knowledge of and a brief introduction to the suitable archives, region-specific taphonomy, state-of-the-art methodologies, and research questions of sedaDNA on the Tibetan Plateau; (ii) review published and ongoing sedaDNA studies from the Tibetan Plateau; and (iii) give some recommendations for future sedaDNA study designs. Based on the current knowledge of taphonomy, we infer that deep glacial lakes with freshwater and high clay sediment input, such as those from the southern and southeastern Tibetan Plateau, may have a high potential for sedaDNA studies. Metabarcoding (for microorganisms and plants), metagenomics (for ecosystems), and hybridization capture (for prehistoric humans) are three primary sedaDNA approaches which have been successfully applied on the Tibetan Plateau, but their power is still limited by several technical issues, such as PCR bias and incompleteness of taxonomic reference databases. Setting up high-quality and open-access regional taxonomic reference databases for the Tibetan Plateau should be given priority in the future. To conclude, the archival, taphonomic, and methodological conditions of the Tibetan Plateau are favorable for performing sedaDNA studies. More research should be encouraged to address questions about long-term ecological dynamics at ecosystem scale and to bring the paleoecology of the Tibetan Plateau into a new era. KW - Sedimentary ancient DNA (sedaDNA) KW - Tibetan Plateau KW - Environmental DNA KW - Taphonomy KW - Ecosystem KW - Biodiversity KW - Paleoecology KW - Paleogeography Y1 - 2022 U6 - https://doi.org/10.1016/j.quascirev.2022.107703 SN - 0277-3791 SN - 1873-457X VL - 293 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Zhang, Di A1 - Cao, Kai A1 - Yuan, Xiaoping A1 - Wang, Guocan A1 - van der Beek, Pieter A. T1 - Late Oligocene-early Miocene origin of the First Bend of the Yangtze River explained by thrusting-induced river reorganization JF - Geomorphology N2 - The origin of the First Bend of the Yangtze River is key to understanding the birth of the modern Yangtze River. Despite considerable efforts, the timing and mechanism of formation of the First Bend remain highly debated. Inverse river-profile modeling of three tributaries (Chongjiang, Lima, and Gudu) of the Jinsha River, integrated with regional tectonic and geomorphic interpretations, allows the onset of incision at the First Bend to be constrained to 28-20 Ma. The spatio-temporal coincidence of initial river incision and activity of Yulong Thrust Belt in southeastern Tibet highlights thrusting to be fundamental in reshaping the pre-existing stream network at the First Bend. These results enable us to reinterpret a change in sedimentary environment from a braided river to a swamp-like lake in the Jianchuan Basin south of the First Bend, recording the destruction of the hypothesized southwards-flowing paleo-Jinsha and Shuiluo Rivers at ~36-35 Ma by magmatism. During the late Oligoceneearly Miocene, the paleo-Shuiluo River was diverted to the north by focused rock uplift due to thrusting along the Yulong Thrust Belt, which also led to exhumation of the Jianchuan Basin. Diversion of the paleo-Shuiluo River can be explained by capture from a downstream river in the footwall of the Yulong Thrust Belt. Subsequent rapid headward erosion, that was caused by thrusting-induced drop of local base level, is recorded by upstream younging ages for the onset of incision and led to the formation of the First Bend. The combination of new ages for the onset of incision at 28-20 Ma at the First Bend and younger ages upstream indicates northwards expansion of the Jinsha River at a rate of 62 +/- 18 mm/yr. Our results suggest that the origin of the First Bend was likely triggered by thrusting at 28-20 Ma, after which the Yangtze River formed. KW - Tibetan Plateau KW - Yangtze River KW - river incision KW - inverse modeling Y1 - 2022 U6 - https://doi.org/10.1016/j.geomorph.2022.108303 SN - 0169-555X SN - 1872-695X VL - 411 PB - Elsevier Science CY - Amsterdam [u.a.] ER - TY - JOUR A1 - Cook, Kristen L. A1 - Hovius, Niels A1 - Wittmann-Oelze, Hella A1 - Heimsath, Arjun M. A1 - Lee, Yuan-Hsi T1 - Causes of rapid uplift and exceptional topography of Gongga Shan on the eastern margin of the Tibetan Plateau JF - Earth & planetary science letters N2 - Erosion and tectonic uplift are widely thought to be coupled through feedbacks involving orographic precipitation, relief development, and crustal weakening. In many orogenic systems, it can be difficult to distinguish whether true feedbacks exist, or whether observed features are a consequence of tectonic forcing. To help elucidate these interactions, we examine Gongga Shan, a 7556 m peak on the eastern margin of the Tibetan Plateau where cosmogenic Be-10 basin-wide erosion rates reach >5 mm/yr, defining a region of localized rapid erosion associated with a restraining bend in the left-lateral Xianshuihe Fault. Erosion rates are consistent with topography, thermochronometry, and geodetic data, suggesting a stable pattern of uplift and exhumation over at least the past 2-3 My. Transpression along the Xianshuihe Fault, orographically enhanced precipitation, thermally weakened crust, and substantial local relief all developed independently in the Gongga region and existed there prior to the uplift of Gongga Shan. However, only where all of these conditions are present do the observed topographic and erosional extremes exist, and their relative timing indicates that these conditions are not a consequence of rapid uplift. We conclude that their collocation at 3-4 Ma set into motion a series of feedbacks between erosion and uplift that has resulted in the exceptionally high topography and rapid erosion rates observed today. KW - cosmogenic erosion rates KW - Tibetan Plateau KW - climate-tectonic feedbacks Y1 - 2017 U6 - https://doi.org/10.1016/j.epsl.2017.10.043 SN - 0012-821X SN - 1385-013X VL - 481 SP - 328 EP - 337 PB - Elsevier CY - Amsterdam ER - TY - GEN A1 - Licht, Alexis A1 - Dupont-Nivet, Guillaume A1 - Pullen, Alex A1 - Kapp, Paul A1 - Abels, Hemmo A. A1 - Lai, Zulong A1 - Guo, ZhaoJie A1 - Abell, Jordan A1 - Giesler, Dominique T1 - Resilience of the Asian atmospheric circulation shown by paleogene dust provenance T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - The onset of modern central Asian atmospheric circulation is traditionally linked to the interplay of surface uplift of the Mongolian and Tibetan-Himalayan orogens, retreat of the Paratethys sea from central Asia and Cenozoic global cooling. Although the role of these players has not yet been unravelled, the vast dust deposits of central China support the presence of arid conditions and modern atmospheric pathways for the last 25 million years (Myr). Here, we present provenance data from older (42-33 Myr) dust deposits, at a time when the Tibetan Plateau was less developed, the Paratethys sea still present in central Asia and atmospheric pCO(2) much higher. Our results show that dust sources and near-surface atmospheric circulation have changed little since at least 42 Myr. Our findings indicate that the locus of central Asian high pressures and concurrent aridity is a resilient feature only modulated by mountain building, global cooling and sea retreat. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1114 KW - Chinese Loess Plateau KW - last glacial maximum KW - Tibetan Plateau KW - Yellow-River KW - climate KW - basin KW - evolution KW - ardification KW - monsoons KW - desert Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-436381 SN - 1866-8372 IS - 1114 ER - TY - GEN A1 - Korzeniowska, Karolina A1 - Korup, Oliver T1 - Object-based detection of lakes prone to seasonal ice cover on the Tibetan Plateau T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - The Tibetan Plateau, the world's largest orogenic plateau, hosts thousands of lakes that play prominent roles as water resources, environmental archives, and sources of natural hazards such as glacier lake outburst floods. Previous studies have reported that the size of lakes on the Tibetan Plateau has changed rapidly in recent years, possibly because of atmospheric warming. Tracking these changes systematically with remote sensing data is challenging given the different spectral signatures of water, the potential for confusing lakes with glaciers, and difficulties in classifying frozen or partly frozen lakes. Object-based image analysis (OBIA) offers new opportunities for automated classification in this context, and we have explored this method for mapping lakes from LANDSAT images and Shuttle Radar Topography Mission (SRTM) elevation data. We tested our algorithm for most of the Tibetan Plateau, where lakes in tectonic depressions or blocked by glaciers and sediments have different surface colours and seasonal ice cover in images obtained in 1995 and 2015. We combined a modified normalised difference water index (MNDWI) with OBIA and local topographic slope data in order to classify lakes with an area > 10 km(2). Our method derived 323 water bodies, with a total area of 31,258 km(2), or 2.6% of the study area (in 2015). The same number of lakes had covered only 24,892 km(2) in 1995; lake area has increased by -26% in the past two decades. The classification had estimated producer's and user's accuracies of 0.98, with a Cohen's kappa and F-score of 0.98, and may thus be a useful approximation for quantifying regional hydrological budgets. We have shown that our method is flexible and transferable to detecting lakes in diverse physical settings on several continents with similar success rates. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1037 KW - Tibetan Plateau KW - lakes KW - LANDSAT KW - SRTM KW - MNDWI KW - OBIA KW - change detection Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-475037 SN - 1866-8372 IS - 1037 ER - TY - JOUR A1 - Huang, Wentao A1 - Jackson, Michael J. A1 - Dekkers, Mark J. A1 - Zhang, Yang A1 - Zhang, Bo A1 - Guo, Zhaojie A1 - Dupont-Nivet, Guillaume T1 - Challenges in isolating primary remanent magnetization from Tethyan carbonate rocks on the Tibetan Plateau: Insight from remagnetized Upper Triassic limestones in the eastern Qiangtang block JF - Earth & planetary science letters N2 - Carbonate rocks, widely used for paleomagnetically quantifying the drift history of the Gondwana derived continental blocks of the Tibetan Plateau and evolution of the Paleo/Meso/Neo-Tethys Oceans, are prone to pervasive remagnetization. Identifying remagnetization is difficult because it is commonly undetectable through the classic paleomagnetic field tests. Here we apply comprehensive paleomagnetic, rock magnetic, and petrographic studies to upper Triassic limestones in the eastern Qiangtang block. Our results reveal that detrital/biogenic magnetite, which may carry the primary natural remanent magnetization (NRM), is rarely preserved in these rocks. In contrast, authigenic magnetite and hematite pseudomorphs after pyrite, and monoclinic pyrrhotite record three episodes of remagnetization. The earliest remagnetization was induced by oxidation of early diagenetic pyrite to magnetite, probably related to the collision between the northeastern Tibetan Plateau and the Qiangtang block after closure of the Paleo-Tethys Ocean in the Late Triassic. The second remagnetization, residing in hematite and minor goethite, which is the further subsurface oxidation product of pyrite/magnetite, is possibly related to the development of the localized Cenozoic basins soon after India-Asia collision in the Paleocene. The youngest remagnetization is a combination of thermoviscous and chemical remanent magnetization carried by authigenic magnetite and pyrrhotite, respectively. Our analyses suggest that a high supply of organic carbon during carbonate deposition, prevailing sulfate reducing conditions during early diagenesis, and widespread orogenic fluid migration related to crustal shortening during later diagenesis, have altered the primary remanence of the shallow-water Tethyan carbonate rocks of the Tibetan Plateau. We emphasize that all paleomagnetic results from these rocks must be carefully examined for remagnetization before being used for paleogeographic reconstructions. Future paleomagnetic investigations of the carbonate rocks in orogenic belts should be accompanied by thorough rock magnetic and petrographic studies to determine the origin of the NRM. (C) 2019 Elsevier B.V. All rights reserved. KW - Triassic limestone KW - remagnetization KW - Tibetan Plateau Y1 - 2019 U6 - https://doi.org/10.1016/j.epsl.2019.06.035 SN - 0012-821X SN - 1385-013X VL - 523 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Korzeniowska, Karolina A1 - Korup, Oliver T1 - Object-Based Detection of Lakes Prone to Seasonal Ice Cover on the Tibetan Plateau JF - Remote sensing KW - Tibetan Plateau KW - lakes KW - LANDSAT KW - SRTM KW - MNDWI KW - OBIA KW - change detection Y1 - 2017 U6 - https://doi.org/10.3390/rs9040339 SN - 2072-4292 VL - 9 PB - MDPI CY - Basel ER - TY - JOUR A1 - Li, Kai A1 - Liu, Xingqi A1 - Wang, Yongbo A1 - Herzschuh, Ulrike A1 - Ni, Jian A1 - Liao, Mengna A1 - Xiao, Xiayun T1 - Late Holocene vegetation and climate change on the southeastern Tibetan Plateau: Implications for the Indian Summer Monsoon and links to the Indian Ocean Dipole JF - Quaternary science reviews : the international multidisciplinary research and review journal N2 - The Indian Summer Monsoon (ISM) is one of the most important climate systems, whose variability and driving mechanisms are of broad interest for academic and societal communities. Here, we present a well-dated high-resolution pollen analysis from a 4.82-m long sediment core taken from Basomtso, in the southeastern Tibetan Plateau (TP), which depicts the regional climate changes of the past millennium. Our results show that subalpine coniferous forest was dominant around Basomtso from ca. 867 to ca. 750 cal. yr BP, indicating a warm and semi-humid climate. The timberline in the study area significantly decreased from ca. 750 to ca.100 cal. yr BP, and a cold climate, corresponding to the Little Ice Age (LIA) prevailed. Since ca. 100 cal. yr BP, the vegetation type changed to forest-meadow with rising temperatures and moisture. Ordination analysis reveals that the migration of vegetation was dominated by regional temperatures and then by moisture. Further comparisons between the Basomtso pollen record and the regional temperature reconstructions underscore the relevance of the Basomtso record from the southeastern TP for regional and global climatologies. Our pollen based moisture reconstruction demonstrates the strong multicentennial-scale link to ISM variability, providing solid evidence for the increase of monsoonal strengths over the past four centuries. Spectral analysis indicates the potential influence of solar forcing. However, a closer relationship has been observed between multicentennial ISM variations and Indian Ocean sea surface temperature anomalies (SSTs), suggesting that the variations in monsoonal precipitation over the southeastern TP are probably driven by the Indian Ocean Dipole on the multicentennial scale. (C) 2017 Elsevier Ltd. All rights reserved. KW - Indian Summer Monsoon KW - Late Holocene KW - Pollen record KW - Basomtso KW - Tibetan Plateau KW - Indian ocean dipole Y1 - 2017 U6 - https://doi.org/10.1016/j.quascirev.2017.10.020 SN - 0277-3791 VL - 177 SP - 235 EP - 245 PB - Elsevier CY - Oxford ER - TY - GEN A1 - Dallmeyer, Anne A1 - Claussen, Martin A1 - Ni, Jian A1 - Cao, Xianyong A1 - Wang, Yongbo A1 - Fischer, Nils A1 - Pfeiffer, Madlene A1 - Jin, Liya A1 - Khon, Vyacheslav A1 - Wagner, Sebastian A1 - Haberkorn, Kerstin A1 - Herzschuh, Ulrike T1 - Biome changes in Asia since the mid-Holocene BT - An analysis of different transient Earth system model simulations T2 - Postprints der Universität Potsdam : Mathematisch Naturwissenschaftliche Reihe N2 - The large variety of atmospheric circulation systems affecting the eastern Asian climate is reflected by the complex Asian vegetation distribution. Particularly in the transition zones of these circulation systems, vegetation is supposed to be very sensitive to climate change. Since proxy records are scarce, hitherto a mechanistic understanding of the past spatio-temporal climate-vegetation relationship is lacking. To assess the Holocene vegetation change and to obtain an ensemble of potential mid-Holocene biome distributions for eastern Asia, we forced the diagnostic biome model BIOME4 with climate anomalies of different transient Holocene climate simulations performed in coupled atmosphere-ocean(-vegetation) models. The simulated biome changes are compared with pollen-based biome records for different key regions. In all simulations, substantial biome shifts during the last 6000 years are confined to the high northern latitudes and the monsoon-westerly wind transition zone, but the temporal evolution and amplitude of change strongly depend on the climate forcing. Large parts of the southern tundra are replaced by taiga during the mid-Holocene due to a warmer growing season and the boreal treeline in northern Asia is shifted northward by approx. 4 degrees in the ensemble mean, ranging from 1.5 to 6 degrees in the individual simulations, respectively. This simulated treeline shift is in agreement with pollen-based reconstructions from northern Siberia. The desert fraction in the transition zone is reduced by 21% during the mid-Holocene compared to pre-industrial due to enhanced precipitation. The desert-steppe margin is shifted westward by 5 degrees (1-9 degrees in the individual simulations). The forest biomes are expanded north-westward by 2 degrees, ranging from 0 to 4 degrees in the single simulations. These results corroborate pollen-based reconstructions indicating an extended forest area in north-central China during the mid-Holocene. According to the model, the forest-to-non-forest and steppe-to-desert changes in the climate transition zones are spatially not uniform and not linear since the mid-Holocene. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 643 KW - Last Glacial Maximum KW - Eastern Continental Asia KW - summer monsoon precipitation KW - PMIP2 coupled simulations KW - Global Vegetation Model KW - northern high‐latitudes KW - Holocene climate change KW - Tibetan Plateau KW - environmental changes KW - Inner Mongolia Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-418755 SN - 1866-8372 IS - 643 SP - 107 EP - 134 ER - TY - GEN A1 - Aichner, Bernhard A1 - Feakins, Sarah J. A1 - Lee, J. E. A1 - Herzschuh, Ulrike A1 - Liu, X. T1 - High-resolution leaf wax carbon and hydrogen isotopic record of the late Holocene paleoclimate in arid Central Asia T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - Central Asia is located at the confluence of large-scale atmospheric circulation systems. It is thus likely to be highly susceptible to changes in the dynamics of those systems; however, little is still known about the regional paleoclimate history. Here we present carbon and hydrogen isotopic compositions of n-alkanoic acids from a late Holocene sediment core from Lake Karakuli (eastern Pamir, Xinjiang Province, China). Instrumental evidence and isotopeenabled climate model experiments with the Laboratoire de Meteorologie Dynamique Zoom model version 4 (LMDZ4) demonstrate that delta D values of precipitation in the region are influenced by both temperature and precipitation amount. We find that these parameters are inversely correlated on an annual scale, i.e., the climate has varied between relatively cool and wet and more warm and dry over the last 50 years. Since the isotopic signals of these changes are in the same direction and therefore additive, isotopes in precipitation are sensitive recorders of climatic changes in the region. Additionally, we infer that plants use year-round precipitation (including snowmelt), and thus leaf wax delta D values must also respond to shifts in the proportion of moisture derived from westerly storms during late winter and early spring. Downcore results give evidence for a gradual shift to cooler and wetter climates between 3.5 and 2.5 cal kyr BP, interrupted by a warm and dry episode between 3.0 and 2.7 kyr BP. Further cool and wet episodes occur between 1.9 and 1.5 and between 0.6 and 0.1 kyr BP, the latter coeval with the Little Ice Age. Warm and dry episodes from 2.5 to 1.9 and 1.5 to 0.6 kyr BP coincide with the Roman Warm Period and Medieval Climate Anomaly, respectively. Finally, we find a drying tend in recent decades. Regional comparisons lead us to infer that the strength and position of the westerlies, and wider northern hemispheric climate dynamics, control climatic shifts in arid Central Asia, leading to complex local responses. Our new archive from Lake Karakuli provides a detailed record of the local signatures of these climate transitions in the eastern Pamir. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 506 KW - North-Atlantic climate KW - Aral Sea basin KW - delta-D values KW - last 15 kyr KW - athmospheric circulation KW - ice core KW - moisture evolution KW - lipid biomarkers KW - Tibetan Plateau KW - Eastern pamirs Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-408442 SN - 1866-8372 IS - 506 ER - TY - GEN A1 - Mischke, Steffen A1 - Zhang, Chengjun A1 - Fan, Rong T1 - Early to mid-Holocene lake high-stand sediments at Lake Donggi Cona, northeastern Tibetan Plateau, China - T2 - Quaternary research : an interdisciplinary journal KW - Microfossils KW - Ostracoda KW - Lake level KW - Wetlands KW - Depositional setting KW - Tibetan Plateau KW - Holocene Y1 - 2015 U6 - https://doi.org/10.1016/j.yqres.2014.06.005 SN - 0033-5894 SN - 1096-0287 VL - 83 IS - 1 SP - 256 EP - 258 PB - Elsevier CY - San Diego ER - TY - JOUR A1 - Wang, Rong A1 - Zhang, Yongzhan A1 - Wünnemann, Bernd A1 - Biskaborn, Boris A1 - Yin, He A1 - Xia, Fei A1 - Zhou, Lianfu A1 - Diekmann, Bernhard T1 - Linkages between Quaternary climate change and sedimentary processes in Hala Lake, northern Tibetan Plateau, China JF - Journal of Asian earth sciences N2 - Profundal lake sediment cores are often interpreted in line with diverse and detailed sedimentological processes to infer paleoenvironmental conditions. The effects of frozen lake surfaces on terrigenous sediment deposition and how climate changes on the Tibetan Plateau are reflected in these lakes, however, is seldom discussed. A lake sediment core from Hala Lake (590 km(2)), northeastern Tibetan Plateau spanning the time interval from the Last Glacial Maximum to the present was investigated using high-resolution grain-size composition of lacustrine deposits. Seismic analysis along a north-south profile across the lake was used to infer the sedimentary setting within the lake basin. Periods of freezing and melting processes on the lake surface were identified by MODIS (MOD10A1) satellite data. End-member modeling of the grain size distribution allowed the discrimination between lacustrine, eolian and fluvial sediments. The dominant clay sedimentation (slack water type) during the global Last Glacial Maximum (LGM) reflects ice interceptions in long cold periods, in contrast to abundant eolian input during abrupt cold events. Therefore, fluvial and slack water sedimentation processes can indicate changes in the local paleoclimate during periods of the lake being frozen, when eolian input was minor. Inferred warm (i.e., similar to 22.7 and 19.5 cal. ka BP) and cold (i.e., similar to 11-9 and 3-1.5 cal. ka BP) spells have significant environmental impacts, not only in the regional realm, but they are also coherent with global-scale climate events. The eolian input generally follows the trend of the mid-latitude westerly wind dynamics in winter, contributing medium-sized sand to the lake center, deposited within the ice cover during icing and melting phases. Enhanced input was dominant during the Younger Dryas, Heinrich Event 1 and at around 8.2 ka, equivalent to the well-known events of the North Atlantic realm. (C) 2015 Elsevier Ltd. All rights reserved. KW - Tibetan Plateau KW - Lake deposits KW - End-member modeling KW - Grain size KW - Pleistocene and Holocene climate Y1 - 2015 U6 - https://doi.org/10.1016/j.jseaes.2015.04.008 SN - 1367-9120 SN - 1878-5786 VL - 107 SP - 140 EP - 150 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Wang, Yongbo A1 - Herzschuh, Ulrike A1 - Liu, Xingqi A1 - Korup, Oliver A1 - Diekmann, Bernhard T1 - A high-resolution sedimentary archive from landslide-dammed Lake Mengda, north-eastern Tibetan Plateau JF - Journal of paleolimnolog N2 - Lacustrine sediments have been widely used to investigate past climatic and environmental changes on millennial to seasonal time scales. Sedimentary archives of lakes in mountainous regions may also record non-climatic events such as earthquakes. We argue herein that a set of 64 annual laminae couplets reconciles a stratigraphically inconsistent accelerator mass spectrometry (AMS) C-14 chronology in a similar to 4-m-long sediment core from Lake Mengda, in the north-eastern Tibetan Plateau. The laminations suggest the lake was formed by a large landslide, triggered by the 1927 Gulang earthquake (M = 8.0). The lake sediment sequence can be separated into three units based on lithologic, sedimentary, and isotopic characteristics. Starting from the bottom of the sequence, these are: (1) unweathered, coarse, sandy valley-floor deposits or landslide debris that pre-date the lake, (2) landslide-induced, fine-grained soil or reworked landslide debris with a high organic content, and (3) lacustrine sediments with low organic content and laminations. These annual laminations provide a high-resolution record of anthropogenic and environmental changes during the twentieth century, recording enhanced sediment input associated with two phases of construction activities. The high mean sedimentation rates of up to 4.8 mm year(-1) underscore the potential for reconstructing such distinct sediment pulses in remote, forested, and seemingly undisturbed mountain catchments. KW - Earthquake KW - Landslide KW - Natural dam KW - Tibetan Plateau Y1 - 2014 U6 - https://doi.org/10.1007/s10933-012-9666-6 SN - 0921-2728 SN - 1573-0417 VL - 51 IS - 2 SP - 303 EP - 312 PB - Springer CY - Dordrecht ER - TY - JOUR A1 - Wischnewski, Juliane A1 - Herzschuh, Ulrike A1 - Ruehland, Kathleen M. A1 - Braeuning, Achim A1 - Mischke, Steffen A1 - Smol, John P. A1 - Wang, Lily T1 - Recent ecological responses to climate variability and human impacts in the Nianbaoyeze Mountains (eastern Tibetan Plateau) inferred from pollen, diatom and tree-ring data JF - Journal of paleolimnolog N2 - The Tibetan Plateau is a region that is highly sensitive to recent global warming, but the complexity and heterogeneity of its mountainous landscape can result in variable responses. In addition, the scarcity and brevity of regional instrumental and palaeoecological records still hamper our understanding of past and present patterns of environmental change. To investigate how the remote, high-alpine environments of the Nianbaoyeze Mountains, eastern Tibetan Plateau, are affected by climate change and human activity over the last similar to 600 years, we compared regional tree-ring studies with pollen and diatom remains archived in the dated sediments of Dongerwuka Lake (33.22A degrees N, 101.12A degrees E, 4,307 m a.s.l.). In agreement with previous studies from the eastern Tibetan Plateau, a strong coherence between our two juniper-based tree-ring chronologies from the Nianbaoyeze and the Anemaqin Mountains was observed, with pronounced cyclical variations in summer temperature reconstructions. A positive directional trend to warmer summer temperatures in the most recent decades, was, however, not observed in the tree-ring record. Likewise, our pollen and diatom spectra showed minimal change over the investigated time period. Although modest, the most notable change in the diatom relative abundances was a subtle decrease in the dominant planktonic Cyclotella ocellata and a concurrent increase in small, benthic fragilarioid taxa in the similar to 1820s, suggesting higher ecosystem variability. The pollen record subtly indicates three periods of increased cattle grazing activity (similar to 1400-1480 AD, similar to 1630-1760 AD, after 1850 AD), but shows generally no significant vegetation changes during past similar to 600 years. The minimal changes observed in the tree-ring, diatom and pollen records are consistent with the presence of localised cooling centres that are evident in instrumental and tree-ring data within the southeastern and eastern Tibetan Plateau. Given the minor changes in regional temperature records, our complacent palaeoecological profiles suggest that climatically induced ecological thresholds have not yet been crossed in the Nianbaoyeze Mountains region. KW - Tibetan Plateau KW - Nianbaoyeze Mountains KW - Pollen KW - Diatoms KW - Tree-ring KW - Climate change KW - Human impact Y1 - 2014 U6 - https://doi.org/10.1007/s10933-013-9747-1 SN - 0921-2728 SN - 1573-0417 VL - 51 IS - 2 SP - 287 EP - 302 PB - Springer CY - Dordrecht ER - TY - JOUR A1 - Mischke, Steffen A1 - Lai, Zhongping A1 - Zhang, Chengjun T1 - Re-assessment of the paleoclimate implications of the Shell Bar in the Qaidam Basin, China JF - Journal of paleolimnolog N2 - The Shell Bar in the Qaidam Basin, China, is a prominent geological feature composed of millions of densely packed Corbicula shells. Since the mid 1980s, it has been regarded as evidence for existence of a large lake during Marine Isotope Stage (MIS) 3 in the presently hyper-arid Qaidam Basin. Early studies suggested the bivalve shells accumulated at the shore of a large lake, whereas more recent work led to the conclusion that the Shell Bar was formed within a deeper water body. Based on our re-assessment of sediments and fossils from the Shell Bar, investigation of exposed fluvio-lacustrine sections upstream of the Shell Bar and study of nearby modern streams, we infer that the Shell Bar represents a stream deposit. Corbicula is a typical stream-dweller around the world. Preservation of Corbicula shells of different sizes, as well as occurrence of many articulated shells, provide evidence against post-mortem transport and accumulation along a lake shore. Additionally, the SE-NW alignment of the Shell Bar is similar to modern intermittent stream beds in its vicinity and corresponds to the present-day slope towards the basin centre further NW, and furthermore, the predominantly sandy sediments also indicate that the Shell Bar was formed in a stream. Abundant ostracod shells in the Shell Bar sediments originated from stream-dwelling species that are abundant in modern streams in the vicinity of the Shell Bar, or in part from fluvio-lacustrine sediments exposed upstream of the Shell Bar, as a result of erosion and re-deposition. Deflation of alluvial fine-grained sediments in the Shell Bar region and protection of the stream deposits by the large and thick-walled Corbicula shells reversed the former channel relief and yielded the modern exposure, which is a prominent morphological feature. Occurrence of Corbicula shells in the Qaidam Basin indicates climate was apparently warmer than present during the formation of the Shell Bar because Corbicula does not live at similar or higher altitudes in the region today. Because the Shell Bar is no longer considered a deposit formed within a lake, its presence does not indicate paleoclimate conditions wetter than today. KW - Qaidam Basin KW - Tibetan Plateau KW - Late Pleistocene KW - Corbicula KW - Ostracoda KW - Taphonomy Y1 - 2014 U6 - https://doi.org/10.1007/s10933-012-9674-6 SN - 0921-2728 SN - 1573-0417 VL - 51 IS - 2 SP - 179 EP - 195 PB - Springer CY - Dordrecht ER - TY - JOUR A1 - Herzschuh, Ulrike A1 - Borkowski, Janett A1 - Schewe, Jacob A1 - Mischke, Steffen A1 - Tian, Fang T1 - Moisture-advection feedback supports strong early-to-mid Holocene monsoon climate on the eastern Tibetan Plateau as inferred from a pollen-based reconstruction JF - Palaeogeography, palaeoclimatology, palaeoecology : an international journal for the geo-sciences N2 - (Paleo-)climatologists are challenged to identify mechanisms that cause the observed abrupt Holocene monsoon events despite the fact that monsoonal circulation is assumed to be driven by gradual insolation changes. Here we provide proxy and model evidence to show that moisture-advection feedback can lead to a non-linear relationship between sea-surface and continental temperatures and monsoonal precipitation. A pollen record from Lake Ximencuo (Nianbaoyeze Mountains) indicates that vegetation from the eastern margin of the Tibetan Plateau was characterized by alpine deserts and glacial flora after the Last Glacial Maximum (LGM) (21-15.5 cal kyr BP), by alpine meadows during the Late Glacial (15.5-10.4 cal kyr BP) and second half of the Holocene (5.0 cal kyr BP to present) and by mixed forests during the first half of the Holocene (10.4-5.0 cal kyr BP). The application of pollen-based transfer functions yields an abrupt temperature increase at 10.4 cal kyr BP and a decrease at 5.0 cal kyr BP of about 3 degrees C. By applying endmember modeling to grain-size data from the same sediment core we infer that frequent fluvial events (probably originating from high-magnitude precipitation events) were more common in the early and mid Holocene. We assign the inferred exceptional strong monsoonal circulation to the initiation of moisture-advection feedback, a result supported by a simple model that reproduces this feedback pattern over the same time period. (C) 2014 Published by Elsevier B.V. KW - Moisture-advection feedback KW - Monsoon KW - Tibetan Plateau KW - Holocene KW - Last Glacial Maximum KW - Pollen-climate calibration Y1 - 2014 U6 - https://doi.org/10.1016/j.palaeo.2014.02.022 SN - 0031-0182 SN - 1872-616X VL - 402 SP - 44 EP - 54 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Herzschuh, Ulrike A1 - Ni, Jian A1 - Birks, H. John B. A1 - Böhner, Jürgen T1 - Driving forces of mid-Holocene vegetation shifts on the upper Tibetan Plateau, with emphasis on changes in atmospheric CO2 concentrations JF - Quaternary science reviews : the international multidisciplinary research and review journal N2 - Numerous pollen records across the upper Tibetan Plateau indicate that in the early part of the mid-Holocene, Kobresia-rich high-alpine meadows invaded areas formerly dominated by alpine steppe vegetation rich in Artemisia. We examine climate, land-use, and CO2 concentration changes as potential drivers for this marked vegetation change. The climatic implications of these vegetational shifts are explored by applying a newly developed pollen-based moisture-balance transfer-function to fossil pollen spectra from Koucha Lake on the north-eastern Tibetan Plateau (34.0 degrees N; 97.2 degrees E; 4540 m a.s.l.) and Xuguo Lake on the central Tibetan Plateau (31.97 degrees N; 90.3 degrees E; 4595 m a.s.l.), both located in the meadow-steppe transition zone. Reconstructed moisture-balances were markedly reduced (by similar to 150-180 mm) during the early mid-Holocene compared to the late-Holocene. These findings contradict most other records from the Indian monsoonal realm and also most non-pollen records from the Tibetan Plateau that indicate a rather wet early- and mid-Holocene. The extent and timing of anthropogenic land-use involving grazing by large herbivores on the upper Tibetan Plateau and its possible impacts on high-alpine vegetation are still mostly unknown due to the lack of relevant archaeological evidence. Arguments against a mainly anthropogenic origin of Kobresia high-alpine meadows are the discovery of the widespread expansion of obviously 'natural' Kobresia meadows on the south-eastern Tibetan Plateau during the Lateglacial period indicating the natural origin of this vegetation type and the lack of any concurrence between modern human-driven vegetation shifts and the mid-Holocene compositional changes. Vegetation types are known to respond to atmospheric CO2 concentration changes, at least on glacial-interglacial scales. This assumption is confirmed by our sensitivity study where we model Tibetan vegetation at different CO2 concentrations of 375 (present-day), 260 (early Holocene), and 650 ppm (future scenario) using the BIOME4 global vegetation model. Previous experimental studies confirm that vegetation growing on dry and high sites is particularly sensitive to CO2 changes. Here we propose that the replacement of drought-resistant alpine steppes (that are well adapted to low CO2 concentrations) by mesic Kobresia meadows can, at least, be partly interpreted as a response to the increase of CO2 concentration since 7000 years ago due to fertilization and water-saving effects. Our hypothesis is corroborated by former CO2 fertilization experiments performed on various dry grasslands and by the strong recent expansion of high-alpine meadows documented by remote sensing studies in response to recent CO2 increases. KW - Tibetan Plateau KW - Pollen KW - Holocene KW - Transfer function KW - Kobresia meadow KW - Atmospheric CO2 concentration Y1 - 2011 U6 - https://doi.org/10.1016/j.quascirev.2011.03.007 SN - 0277-3791 VL - 30 IS - 15-16 SP - 1907 EP - 1917 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Wischnewski, Juliane A1 - Mackay, Anson W. A1 - Appleby, Peter G. A1 - Mischke, Steffen A1 - Herzschuh, Ulrike T1 - Modest diatom responses to regional warming on the southeast Tibetan Plateau during the last two centuries JF - Journal of paleolimnolog N2 - A general mean annual temperature increase accompanied with substantial glacial retreat has been noted on the Tibetan Plateau during the last two centuries but most significantly since the mid 1950s. These climate trends are particularly apparent on the southeastern Tibetan Plateau. However, the Tibetan Plateau (due to its heterogeneous mountain landscape) has very complex and spatially differing temperature and precipitations patterns. As a result, intensive palaeolimnological investigations are necessary to decipher these climatic patterns and to understand ecological responses to recent environmental change. Here we present palaeolimnological results from a (210)Pb/(137)Cs-dated sediment core spanning approximately the last 200 years from a remote high-mountain lake (LC6 Lake, working name) on the southeastern Tibetan Plateau. Sediment profiles of diatoms, organic variables (TOC, C:N) and grain size were investigated. The (210)Pb record suggests a period of rapid sedimentation, which might be linked to major tectonic events in the region ca. 1950. Furthermore, unusually high (210)Pb supply rates over the last 50 years suggest that the lake has possibly been subjected to increasing precipitation rates, sediment focussing and/or increased spring thaw. The majority of diatom taxa encountered in the core are typical of slightly acidic to circumneutral, oligotrophic, electrolyte-poor lakes. Diatom species assemblages were rich, and dominated by Cyclotella sp., Achnanthes sp., Aulacoseira sp. and fragilarioid taxa. Diatom compositional change was minimal over the 200-year period (DCCA = 0.85 SD, p = 0.59); only a slightly more diverse but unstable diatom assemblage was recorded during the past 50 years. The results indicate that large-scale environmental changes recorded in the twentieth century (i.e. increased precipitation and temperatures) are likely having an affect on the LC6 Lake, but so far these impacts are more apparent on the lake geochemistry than on the diatom flora. Local and/or regional peculiarities, such as increasing precipitation and cloud cover, or localized climatic phenomena, such as negative climate feedbacks, might have offset the effects of increasing mean surface temperatures. KW - Diatoms KW - Tibetan Plateau KW - Mountain lake KW - Climate change KW - Lake sediments KW - Palaeolimnology Y1 - 2011 U6 - https://doi.org/10.1007/s10933-011-9533-x SN - 0921-2728 VL - 46 IS - 2 SP - 215 EP - 227 PB - Springer CY - Dordrecht ER -