TY  - JOUR
A1  - Zhang, Di
A1  - Cao, Kai
A1  - Yuan, Xiaoping
A1  - Wang, Guocan
A1  - van der Beek, Peter
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  - 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  - 
TY  - JOUR
A1  - Wischnewski, Juliane
A1  - Kramer, Annette
A1  - Kong, Zhaochen
A1  - Mackay, Anson W.
A1  - Simpson, Gavin L.
A1  - Mischke, Steffen
A1  - Herzschuh, Ulrike
T1  - Terrestrial and aquatic responses to climate change and human impact on the southeastern Tibetan Plateau during the past two centuries
JF  - Global change biology
N2  - Rapid population growth and economic development have led to increased anthropogenic pressures on the Tibetan Plateau, causing significant land cover changes with potentially severe ecological consequences. To assess whether or not these pressures are also affecting the remote montane-boreal lakes on the SE Tibetan Plateau, fossil pollen and diatom data from two lakes were synthesized. The interplay of aquatic and terrestrial ecosystem response was explored in respect to climate variability and human activity over the past 200 years. Nonmetric multidimensional scaling and Procrustes rotation analysis were undertaken to determine whether pollen and diatom responses in each lake were similar and synchronous. Detrended canonical correspondence analysis was used to develop quantitative estimates of compositional species turnover. Despite instrumental evidence of significant climatic warming on the southeastern Plateau, the pollen and diatom records indicate very stable species composition throughout their profiles and show only very subtle responses to environmental changes over the past 200 years. The compositional species turnover (0.36-0.94 SD) is relatively low in comparison to the species reorganizations known from the periods during the mid-and early-Holocene (0.64-1.61 SD) on the SE Plateau, and also in comparison to turnover rates of sediment records from climate-sensitive regions in the circum arctic. Our results indicate that climatically induced ecological thresholds are not yet crossed, but that human activity has an increasing influence, particularly on the terrestrial ecosystem in our study area. Synergistic processes of post-Little Ice Age warming, 20th century climate warming and extensive reforestations since the 19th century have initiated a change from natural oak-pine forests to seminatural, likely less resilient pine-oak forests. Further warming and anthropogenic disturbances would possibly exceed the ecological threshold of these ecosystems and lead to severe ecological consequences.
KW  - climate change
KW  - compositional species turnover
KW  - diatoms
KW  - human impact
KW  - pollen
KW  - Procrustes rotation
KW  - Tibetan Plateau
Y1  - 2011
U6  - https://doi.org/10.1111/j.1365-2486.2011.02474.x
SN  - 1354-1013
VL  - 17
IS  - 11
SP  - 3376
EP  - 3391
PB  - Wiley-Blackwell
CY  - Malden
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  - Wang, Yongbo
A1  - Liu, Xingqi
A1  - Mischke, Steffen
A1  - Herzschuh, Ulrike
T1  - Environmental constraints on lake sediment mineral compositions from the Tibetan Plateau and implications for paleoenvironment reconstruction
JF  - Journal of paleolimnolog
N2  - Inorganic minerals form a major component of lacustrine sediments and have the potential to reveal detailed information on previous climatic and hydrological conditions. The ability to extract such information however, has been restricted by a limited understanding of the relationships between minerals and the environment. In an attempt to fill in this gap in our knowledge, 146 surface sediment samples have been investigated from 146 lakes on the Tibetan Plateau. The mineral compositions derived from these samples by X-Ray Diffraction (XRD) were used to examine the relationships between mineral compositions and the environmental variables determined for each site. Statistical techniques including Multivariate regression trees (MRT) and Redundancy Analysis (RDA), based on the mineral spectra and environmental variables, reveal that the electrical conductivity (EC) and Mg/Ca ratios of lake water are the most important controls on the composition of endogenic minerals. No endogenic minerals precipitate under hyper-fresh water conditions (EC lower than 0.13 mS/cm), with calcite commonly forming in water with EC values above 0.13 mS/cm. Between EC values of 0.13 and 26 mS/cm the mineral composition of lake sediments can be explained in terms of variations in the Mg/Ca ratio: calcite dominates at Mg/Ca ratios of less than 33, whereas aragonite commonly forms when the ratio is greater than 33. Where EC values are between 26 and 39 mS/cm, monohydrocalcite precipitates together with calcite and aragonite; above 39 mS/cm, gypsum and halite commonly form. Information on the local geological strata indicates that allogenic (detrital) mineral compositions are primarily influenced by the bedrock compositions within the catchment area. By applying these relationships to the late glacial and Holocene mineral record from Chaka Salt Lake, five lake stages have been identified and their associated EC conditions inferred. The lake evolved from a freshwater lake during the late glacial (before 11.4 cal. ka BP) represented by the lowest EC values (< 0.13 mS/cm), to a saline lake with EC values slightly higher than 39 mS/cm during the early and mid Holocene (ca. 11.4-5.3 cal. ka BP), and finally to a salt lake (after 5.3 cal. ka BP). These results illustrate the utility of our mineral-environmental model for the quantitative reconstruction of past environmental conditions from lake sediment records.
KW  - Mineral composition
KW  - XRD
KW  - Multivariate regression trees
KW  - Electrical conductivity
KW  - Paleolimnology
KW  - Tibetan Plateau
Y1  - 2012
U6  - https://doi.org/10.1007/s10933-011-9549-2
SN  - 0921-2728
VL  - 47
IS  - 1
SP  - 71
EP  - 85
PB  - Springer
CY  - Dordrecht
ER  - 
TY  - JOUR
A1  - Wang, Yongbo
A1  - Liu, Xingqi
A1  - Herzschuh, Ulrike
A1  - Yang, Xiangdong
A1  - Birks, H. John B.
A1  - Zhang, Enlou
A1  - Tong, Guobang
T1  - Temporally changing drivers for late-Holocene vegetation changes on the northern Tibetan Plateau
JF  - Palaeogeography, palaeoclimatology, palaeoecology : an international journal for the geo-sciences
N2  - Fossil pollen records have been widely used as indicators of past changes in vegetation and variations in climate. The driving mechanisms behind these vegetation changes have, however, remained unclear. In order to evaluate vegetation changes that have occurred in the northern part of the Tibetan Plateau and the possible drivers behind these changes, we have applied a moving-window Redundancy Analysis (RDA) to high resolution (10-15 years) pollen and sedimentary data from Lake Kusai covering the last 3770 years. Our analyses reveal frequent fluctuations in the relative abundances of alpine steppe and alpine desert components. The sedimentary proxies (including total organic carbon content, total inorganic carbon content, and "end-member" indices from grain-size analyses) that explain statistically some of the changes in the pollen assemblage vary significantly with time, most probably reflecting multiple underlying driving processes. Climate appears to have had an important influence on vegetation changes when conditions were relatively wet and stable. However, a gradual decrease in vegetation cover was identified after 1500 cal a BP, after which the vegetation appears to have been affected more by extreme events such as dust-storms or fluvial erosion than by general climatic trends. Furthermore, pollen spectra over the last 600 years are shown by Procrustes analysis to be statistically different from those recovered from older samples, which we attribute to increased human impact that resulted in unprecedented changes to the vegetation composition. Overall, changes in vegetation and climate on the northern part of the Tibetan Plateau appear to have roughly followed the evolution of the Asian Summer Monsoon. After taking into account the highly significant millennial (1512 years) periodicity revealed by time-series analysis, the regional vegetation and climate changes also show variations that appear to match variations in the mid-latitude westerlies.
KW  - Asian Summer Monsoon
KW  - Late-Holocene
KW  - Pollen
KW  - Procrustes analysis
KW  - Redundancy analysis
KW  - Tibetan Plateau
KW  - Vegetation
KW  - Westerlies
Y1  - 2012
U6  - https://doi.org/10.1016/j.palaeo.2012.06.022
SN  - 0031-0182
VL  - 353
IS  - 8
SP  - 10
EP  - 20
PB  - Elsevier
CY  - Amsterdam
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  - Wang, Yongbo
A1  - Herzschuh, Ulrike
T1  - Reassessment of Holocene vegetation change on the upper Tibetan Plateau using the pollen-based REVEALS model
JF  - Review of palaeobotany and palynology : an international journal
N2  - Previous studies based on fossil pollen data have reported significant changes in vegetation on the alpine Tibetan Plateau during the Holocene. However, since the relative proportions of fossil pollen taxa are largely influenced by individual pollen productivities and the dispersal characteristics, such inferences on vegetation have the potential to be considerably biased. We therefore examined the modern pollen-vegetation relationships for four common pollen species on the Tibetan Plateau, using Extended R-value (ERV) models. Assuming an average radius of 100 m for the sampled lakes, we estimated the relevant source area of pollen (RSAP) to be 2200 m (which represents the distance from the lake). Using Poaceae as the reference taxa (Pollen Productivity Estimate, PPE = 1), ERV Submodel 2 derived relative high PPEs for the steppe and desert taxa: 2.079 +/- 0.432 for Artemisia and 5.379 +/- 1.077 for Chenopodiaceae. Low PPEs were estimated for the Cyperaceae (1.036 +/- 0.012). whose plants are characteristic of the alpine Kobresia meadows. Applying these PPEs to four fossil pollen sequences since the Late Glacial, the plant abundances on the central and north-eastern Tibetan Plateau were quantified using the "Regional Estimates of Vegetation Abundance from Large Sites" (REVEALS) model. The proportions of Artemisia and Chenopodiaceae were greatly reduced compared to their original pollen percentages in the reconstructed vegetation, owing to their high productivities and their dispersal characteristics, while Cyperaceae showed a relative increase in the vegetation reconstruction. The reconstructed vegetation assemblages of the four pollen sequence sites always yielded smaller compositional species turnovers than suggested by the pollen spectra, as revealed by Detrended Canonical Correspondence Analyses (DCCA) of the Holocene sections. The strength of the previously reported vegetation changes may therefore have been overestimated, which indicates the importance of taking into account pollen-vegetation relationships when discussing the potential drivers (such as climate, land use, atmospheric CO(2) concentrations) and implications (such as for land surface-climate feedbacks, carbon storage, and biodiversity) of vegetation change.
KW  - pollen productivity
KW  - vegetation reconstruction
KW  - ERV model
KW  - REVEALS model
KW  - Holocene
KW  - Tibetan Plateau
Y1  - 2011
U6  - https://doi.org/10.1016/j.revpalbo.2011.09.004
SN  - 0034-6667
VL  - 168
IS  - 1
SP  - 31
EP  - 40
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Wang, Rong
A1  - Zhang, Yongzhan
A1  - Wünnemann, Bernd
A1  - Biskaborn, Boris K.
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  - 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  - 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  - 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  - 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  - 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  - Gao, Mingxing
A1  - Zeilinger, Gerold
A1  - Xu, Xiwei
A1  - Wang, Qingliang
A1  - Hao, Ming
T1  - DEM and GIS analysis of geomorphic indices for evaluating recent uplift of the northeastern margin of the Tibetan Plateau, China
JF  - Geomorphology : an international journal on pure and applied geomorphology
N2  - The northeastern margin of the Tibetan Plateau is a tectonically active region consisting of a series of faults with bounded intermountain basins and is located in the transition zone between the Tibetan Plateau and the Loess Plateau. Active deformation that may affect the topography in this region can be quantified using geomorphic indices. Therefore, we applied geomorphic indices such as the hypsometric integral and the stream length gradient index to infer neo-tectonics in the northeastern margin of the Tibetan Plateau. Different time-scaled geodetic leveling data and river incision rates were also integrated into the investigation. The results show that the hypsometric integrals are not significantly affected by lithology but spatially correspond to the hanging walls of thrust faults. The hypsometric integrals are also positively correlated with the leveling data. Although the stream length gradient index is influenced by lithology, its most pronounced anomalies of the stream length gradient are associated with the thrust faults. Consequently, the uplift in the northeast margin of the Tibetan Plateau appeared to be concentrated along the hanging walls of the thrust faults.
KW  - Tectonic geomorphology
KW  - Hypsometry analysis
KW  - Stream length gradient
KW  - Active tectonics
KW  - Leveling data
KW  - Tibetan Plateau
Y1  - 2013
U6  - https://doi.org/10.1016/j.geomorph.2013.02.008
SN  - 0169-555X
VL  - 190
IS  - 20
SP  - 61
EP  - 72
PB  - Elsevier
CY  - Amsterdam
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  -