Papers by Steffen Mischke
Journal of Arid Environments
Journal of Crustacean Biology
Ostracods in Icelandic freshwaters have seldom been researched, with the most comprehensive recor... more Ostracods in Icelandic freshwaters have seldom been researched, with the most comprehensive record from the 1930s. There is a need to update our knowledge of the distribution of ostracods in Iceland as they are an important link in these ecosystems as well as good candidates for biomonitoring. We analysed 25,005 ostracods from 44 lakes, 14 springs, and 10 cave pools. A total of 16 taxa were found, of which seven are new to Iceland. Candona candida (Müller, 1776) is the most widespread species, whereas Cytherissa lacustris (Sars, 1863) and Cypria ophtalmica (Jurine, 1820) are the most abundant, showing great numbers in lakes. Potamocypris fulva (Brady, 1868) is the dominant species in springs. While the fauna of lakes and springs are relatively distinct from each other, cave pools host species that are common in both lakes and springs. Icelandic non-marine ostracods include mostly generalist species, as well as species adapted to cold climates and resemble those of other north Europe...
Acta Geologica Sinica - English Edition
Socio-Environmental Dynamics along the Historical Silk Road
This chapter introduces, by literature reviews, the issue of the links and processes behind clima... more This chapter introduces, by literature reviews, the issue of the links and processes behind climate change, environmental change, and socio-culture change in the past at the ancient Silk Road region. Analyses of the changes of the socioenvironment system in this area enhance our understanding on the regular patterns of coupled natural and social evolution, and is thus of important theoretical and practical significance. We argue that the cross-cutting theme has been to reach beyond simple explanations of environmental or human determinism, but social resilience under environmental impacts. Studies indicate both that climate conditions significantly influence human socio-cultural systems and that the socio-culture systems are certainly resilient to climate impacts. This chapter also summarizes the scope of all chapters in this book by illustrating the specific topics, research areas, focused periods and their inner relationships. The conclusion further summarizes the recent research states on past socio-environmental dynamics and the findings achieved in this book, as well as some outlooks.
Scientific Reports, 2017
Remnants of cities and farmlands in China's hyperarid Tarim Basin indicate that environmental con... more Remnants of cities and farmlands in China's hyperarid Tarim Basin indicate that environmental conditions were significantly wetter two millennia ago in a region which is barren desert today. Historical documents and age data of organic remains show that the Loulan Kingdom flourished during the Han Dynasty (206 BCE-220 CE) but was abandoned between its end and 645 CE. Previous archaeological, geomorphological and geological studies suggest that deteriorating climate conditions led to the abandonment of the ancient desert cities. Based on analyses of lake sediments from Lop Nur in the eastern Tarim Basin and a review of published records, we show that the Loulan Kingdom decline resulted from a man-made environmental disaster comparable to the recent Aral Sea crisis rather than from changing climate. Lop Nur and other lakes within the Han Dynasty realm experienced rapidly declining water levels or even desiccation whilst lakes in adjacent regions recorded rising levels and relatively wet conditions during the time of the Loulan Kingdom decline. Water withdrawal for irrigation farming in the middle reaches of rivers likely caused water shortage downstream and eventually the widespread deterioration of desert oases a long time before man initiated the Aral Sea disaster in the 1960s.
Chin Sci Bull, 2003
A mid to late Holocene exposure in a recently desiccated lake basin in western Inner Mongolia was... more A mid to late Holocene exposure in a recently desiccated lake basin in western Inner Mongolia was investigated with regard to palaeoenvironmental changes and the overall climatic conditions in NW China between 2.7 and 5.4 cal. ka BP. High lake levels of Lake Eastern Juyanze were recorded by ostracod assemblages, shell geochemistry and sedimentology between 5.1 and 4.1 cal. ka BP. Relatively humid conditions and a relatively strong influence of the Asian monsoon are indicated by palynological data for the corresponding period. Lake levels decreased afterwards and short-term regressive events occurred at about 4.1, 3.8 and 3.4 cal. ka BP. The overall trend towards lower lake levels culminated in repeated episodes of desiccation of Lake Eastern Juyanze between 3.2 and 2.9 cal. ka BP, in phase with very arid conditions inferred from the palynological record. Individual regressive events as well as the rapid environmental fluctuations of Lake Eastern Juyanze at about 3.0 cal. ka BP were regarded as driven by mid to late Holocene summer monsoon fluctuations, supported by the Dunde ice core record.
Geobios Lyon, 2002
An exposed section of nearly 13 m thick was investigated in the ancient depression of Lake Easter... more An exposed section of nearly 13 m thick was investigated in the ancient depression of Lake Eastern Juyanze, north-eastern China. The succession of lacustrine and aeolian deposits covers a period from about 5400 to 2700 cal. a BP as indicated by four radiocarbon ages of macro-plant ...
Quaternary Sci Rev, 2010
This paper aims to highlight the potential of using elemental and stable isotope analyses of aqua... more This paper aims to highlight the potential of using elemental and stable isotope analyses of aquatic macrophytes in palaeolimnological studies. Potamogeton pectinatus material was collected from modern plants ( n = 68) and from late glacial and Holocene-aged sediments from Koucha Lake (northeastern Tibetan Plateau; 34.0°N; 97.2°E; 4540 m a.s.l.). It was analyzed for δ 13C Potamogeton (modern: -23 to 0‰, fossil: -19 to -4‰) and δ 15N Potamogeton (modern: -11.0 to +13.8‰, fossil: -9.5 to +6.7‰) in addition to elemental carbon and nitrogen (modern C/N Potamogeton: 7 to 29; fossil: 13 to 68) and sulfur (fossil: 188-899 μmol/g dry weight). Fossil data were interpreted in terms of palaeo-nutrient availability and palaeo-productivity based on the modern relationships between various proxies and certain environmental data. Productivity of Potamogeton pectinatus mats at Koucha Lake as indicated by palaeo-ɛ Potamogeton-TIC (i.e. the enrichment of δ 13C Potamogeton relative to the δ 13C TIC) was reduced during periods of high conductivity, especially between 10.3 and 7.4 cal kyr BP. Potamogeton pectinatus material from these periods was also characterized by high S Potamogeton indicating high sulfide concentrations and anoxic conditions within the sediments. However, C/N Potamogeton ratios and δ 15N Potamogeton from the lower core section were found to have been altered by decompositional processes. A pronounced shift in the aquatic productivity of Lake Koucha occurred at ˜7.4 cal kyr BP when the hydrological conditions shifted towards an open lake system and water depth increased. At this time a strong increase in productivity led to a strong decrease in the water HCO 3- concentration as inferred from the application of a ɛ Potamogeton-TIC-lnHCO 3- transfer function. A comparison of reconstructed productivity changes from Koucha Lake with further environmental proxies suggests that primary productivity changes are probably a function of internal lake dynamics and were only indirectly triggered by climate change.
Marine Geology & Quaternary Geology, 2013
Microbios, Feb 1, 1996
Four chromogenic substrates were compared, and methods were developed for measuring protease acti... more Four chromogenic substrates were compared, and methods were developed for measuring protease activity from fungi. Digestion of azoalbumin, a water-soluble substrate, resulted in dye release most closely proportional to enzyme activity. Substrates insoluble in water were advantageous for time-course studies, and azocoll was more sensitive to digestion and easier to handle than hide powder azure. The optimal pH was 7 for measurement of extracellular protease activity from the Trichoderma strains. Addition of calcium or serine protease inhibitors did not affect crude protease activity. The optimized protocol was used to demonstrate that specific activity of proteases produced by the strains of Trichoderma tested did not correlate with their known biocontrol ability.
ABSTRACT In this paper, we present the sedimentary features and the optical luminescence chronolo... more ABSTRACT In this paper, we present the sedimentary features and the optical luminescence chronology for Nahal Mahanayeem Outlet (NMO), an archaeological open-air site at the southern margin of the Hula Basin (Northern Jordan Valley, Israel). The site is characterized by a lithic assemblage ascribed primarily to the Middle Paleolithic Mousterian tradition and an excellent preservation of floral and faunal remains. Five geological units were distinguished, forming the stratigraphic sequence of the site (occurence from south to north): (1) archaeological sterile, light-colored limnic carbonates; (2) conglomerates of rounded basalt boulders and cobbles forming a hill-like topography; (3) a sequence of dark silty sediments, attached to and overlying the conglomerates, containing the archaeological horizons of the site; (4) a number of channels that cut into the top of unit 3, filled with coarse sand and rounded basalt and limestone gravels of fluvial origin; and (5) a thin sand layer laid down by the present-day Jordan River which covers another unconformity as a result of heavy machinery drainage operations in 1999. The OSL-date for unit 1 yielded a minimum age of 459 ka. Sedimentary features and the embedded fossils suggest that unit 1 can be linked to the Early Pleistocene Gadot Formation. Unit 2 is suggested to be only a local geological feature and could be understand as an indicator for a period of increased erosion. The archaeological horizons form the lower parts of unit 3 and yielded OSL-ages between 65 and 55 ka, indicating an affiliation to the Ashmora Formation with an Upper Pleistocene age for the site. The channel fills of unit 4 can be dated by the recovered artifacts. These range in age from the Upper Paleolithic (Aurignacian) to historic times. Unit 5 is recent. The study of the complex NMO stratigraphy, combined with coherent OSL chronology, has enabled us to reconstruct parts of the geological history of the Hula Basin during the Late Pleistocene. It is this history that forms the background for the human migration and settlement in the Upper Jordan Rift Valley.
Journal of Paleolimnology, May 27, 2011
A general mean annual temperature increase accompanied with substantial glacial retreat has been ... more 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.
Episodes
Earth with mean annual precipitation not exceeding 25 mm in the western central part. Flat salt p... more Earth with mean annual precipitation not exceeding 25 mm in the western central part. Flat salt plains and wind-shaped hills characterise the bare ground over thousands of square kilometres. In contrast to presentday conditions, remnants of ancient shorelines in high positions identified by and about 20 years ago herald of a former large lake but were not investigated further till now.
Two sediment cores (length 13.94 and 12.93 m) have been drilled from the small alpine Lake Luanha... more Two sediment cores (length 13.94 and 12.93 m) have been drilled from the small alpine Lake Luanhaizi in the eastern central Qilian Mountains and correlated by means of magnetic susceptibility (MS). This paper focuses on the lithology and chronology of the longer core, on the results of loss on ignition (LOI), element concentration, thermomagnetic as well as magnetic hysteresis loop measurements, and on the ostracod record.
Quaternary International, 2013
Surface sediment samples were collected from the lakes Heihai, Kusai, Haiding Nuur and Yan Hu, an... more Surface sediment samples were collected from the lakes Heihai, Kusai, Haiding Nuur and Yan Hu, and from streams and ponds in the Kunlun Mountains at the northern margin of the Tibetan Plateau to investigate the sub-fossil ostracod (micro-crustacean) fauna of the region. Among 65 collected samples, 46 ostracod shell-rich samples were used to study the relationship between the ostracod distribution and specific conductivity (SC) of the water, which ranged from 0.6 to 53.0 mS cm À1 . A total of eleven ostracod species was identified from this region, with about half of the species restricted to the Tibetan Plateau and its adjacent mountain areas, and the other half representing Holarctic taxa. Tonnacypris cf. estonica and Tonnacypris tonnensis are reported from the Tibetan Plateau for the first time. Leucocythere sp. is the dominant species and Ilyocypris cf. bradyi is also relatively abundant. The other seven species were recorded with limited abundances apparently due to lower SC tolerances. Leucocythere sp. was recorded over the full SC range from 0.6 to 53 mS cm À1 . Eucypris mareotica is a typical brackish and saline water species, which was found at sample sites with high SC (2.8e53.0 mS cm À1 ). In contrast, Leucocythere dorsotuberosa, Candona candida and Eucypris afghanistanensis prefer freshwater to slightly oligohaline waters with SC < 1.8 mS cm À1 . The SC optimum and tolerance range for each species were determined and compared to earlier reported data from other regions of Central Asia. The results indicate that species assemblage data from fossil ostracod shells have a large potential to provide information on past SC levels and more general climate-determined moisture conditions.
In this paper, we present the sedimentary features and the optical luminescence chronology for Na... more In this paper, we present the sedimentary features and the optical luminescence chronology for Nahal Mahanayeem Outlet (NMO), an archaeological open-air site at the southern margin of the Hula Basin (Northern Jordan Valley, Israel). The site is characterized by a lithic assemblage ascribed primarily to the Middle Paleolithic Mousterian tradition and an excellent preservation of floral and faunal remains. Five geological units were distinguished, forming the stratigraphic sequence of the site (occurence from south to north): (1) archaeological sterile, light-colored limnic carbonates; (2) conglomerates of rounded basalt boulders and cobbles forming a hill-like topography; (3) a sequence of dark silty sediments, attached to and overlying the conglomerates, containing the archaeological horizons of the site; (4) a number of channels that cut into the top of unit 3, filled with coarse sand and rounded basalt and limestone gravels of fluvial origin; and (5) a thin sand layer laid down by...
Quaternary Science Reviews, 2013
A high resolution multieproxy (pollen, grain size, total organic carbon) record from a small moun... more A high resolution multieproxy (pollen, grain size, total organic carbon) record from a small mountain lake (Lake Khuisiin; 46.6 N, 101.8 E; 2270 m a.s.l.) in the southeeastern Khangai Mountains of central Mongolia has been used to explore changes in vegetation and climate over the last 1200 years. The pollen data indicates that the vegetation changed from dry steppe dominated by Poaceae and Artemisia (ca AD 760e950), to Larix forest steppe (ca AD 950e1170), LarixeBetula forest steppe (ca AD 1170e1380), meadow dominated by Cyperaceae and Poaceae (ca AD 1380e1830), and LarixeBetula forest steppe (after w AD 1830). The cold-wet period between AD 1380 and 1830 may relate to the Little Ice Age. Environmental changes were generally subtle and climate change seems to have been the major driver of variations in vegetation until at least the early part of the 20th century, suggesting that either the level of human activity was generally low, or the relationship between human activity and vegetation did not alter substantially between AD 760 and 1830. A review of centennialescale moisture records from China and Mongolia revealed that most areas experienced major changes at ca AD 1500 and AD 1900. However, the moisture availability since AD 1500 varied between sites, with no clear regional pattern or relationship to presenteday conditions. Both the reconstructions and the moisture levels simulation on a millennium scale performed in the MPI Earth System Model indicate that the monsoonewesterlies transition area shows a greater climate variability than those areas influenced by the westerlies, or by the summer monsoon only.
Quaternary Science Reviews, 2015
A multi-proxy Lateglacial environmental record is described from Lake Naleng (31.10 N; 99.75 E, 4... more A multi-proxy Lateglacial environmental record is described from Lake Naleng (31.10 N; 99.75 E, 4200 m above sea level), situated on south-eastern Tibetan Plateau to gain deeper insights into the hydrological and palaeoclimate development since 17.7 cal ka BP. Palynological reconstructions of variations in mean annual precipitation (MAP) and temperature (MAT), sedimentological data and sediment chemistry including weathering indicators provide a multi-faceted picture of local and regional environmental changes since the Lateglacial. Principal component analyses of all parameters provide information on interrelationships between each parameters, which help to evaluate their traceability to temperature and precipitation and to estimate their usability as proxy indicators for local and or regional variations.
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Papers by Steffen Mischke