Author
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Year
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Title
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Abstract
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Publisher
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Affiliated organization
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Heiri, Oliver; Lotter, André F. |
2001 |
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The concentrations of chironomid remains in lake sediments are very variable and, therefore, chironomid stratigraphies often include samples with a low number of counts. Thus, the effect of low count sums on reconstructed temperatures is an important issue when applying chironomid-temperature inference models. Using an existing data set, we simulated low count sums by randomly picking subsets of... |
Journal of Paleolimnology |
Departement Umweltwissenschaften / Geoökologie (Heiri) |
Heiri, Oliver; Lotter, André F.; Lemcke, Gerry |
2001 |
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Five test runs were performed to assess possible bias when performing the loss on ignition (LOI) method to estimate organic matter and carbonate content of lake sediments. An accurate and stable weight loss was achieved after 2 h of burning pure CaCO3 at 950 degreesC, whereas LOI of pure graphite at 530 degreesC showed a direct relation to sample size and exposure time, with only 40-70% of the... |
Journal of Paleolimnology |
Departement Umweltwissenschaften / Geoökologie (Heiri) |
Heiri, Oliver; Lotter, André F. |
2003 |
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Subfossil chironomid analysis was applied to a sediment core from Sagistalsee, a small lake at present-day treeline elevation in the Swiss Alps. During the whole 9000-year stratigraphy the chironomid fauna was dominated by taxa typical of alpine lakes. Major faunistic trends were caused by changes in accumulation rates of three taxa, namely Procladius, Stictochironomus, and Tanytarsus lugens-type.... |
Journal of Paleolimnology |
Departement Umweltwissenschaften / Geoökologie (Heiri) |
Heiri, O.; Birks, H. J. B.; Brooks, S. J.; Velle, G.; Willassen, E. |
2003 |
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We studied the effects of within-lake variation of subfossil chironomid assemblages on chironomid-inferred temperatures in five lakes in southern Norway. In each lake six replicate surface-sediment samples in the deepest part of the lake basin and two transects of seven samples each towards the littoral were analysed for subfossil chironomid assemblages. A quantitative chironomid-July air... |
Palaeogeography, Palaeoclimatology, Palaeoecology |
Departement Umweltwissenschaften / Geoökologie (Heiri) |
Heiri, Oliver; Lotter, André F.; Hausmann, Sonja; Kienast, Felix |
2003 |
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We developed a quantitative chironomid-July air temperature inference model based on surface sediments from 81 Swiss lakes and applied it to the Holocene subfossil chironomid record of Hinterburgsee, a small subalpine lake in the northern Swiss Alps (present-day mean July air temperature of 11.3degreesC). After smoothing to reduce the high between-sample variability of inferred temperatures, the... |
Holocene |
Departement Umweltwissenschaften / Geoökologie (Heiri) |
Heiri, Oliver; Wick, Lucia; van Leeuwen, Jacqueline F. N.; van der Knaap, Willem O.; Lotter, André F. |
2003 |
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Early Holocene reforestation by stone pine (Pinus cembra) and tree birch (Betula pubescens) took place ca. 500 years after the end of the Younger Dryas at Hinterburgsee, a small subalpine lake in the northern Swiss Alps. During the next ca. 3000 years the local vegetation consisted of open woodlands with many pioneer dwarf shrubs and herbs. The expansion of silver fir (Abies alba) at ca. 7400... |
Palaeogeography, Palaeoclimatology, Palaeoecology |
Departement Umweltwissenschaften / Geoökologie (Heiri) |
Heiri, Oliver |
2004 |
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Subfossil chironomids in the surface sediments of five small and shallow Norwegian lakes were studied to determine the within-lake variability of fossil assemblages, changes in chironomid assemblages with respect to water depth, and the representativeness of single samples for the entire chironomid fauna of a lake. In each of the lakes studied, six short sediment cores in the deepest part of the... |
Journal of Paleolimnology |
Departement Umweltwissenschaften / Geoökologie (Heiri) |
Heiri, Oliver; Tinner, Willy; Lotter, André F. |
2004 |
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We analyzed fossil chironomids (nonbiting midges) and pollen in two lake-sediment records to reconstruct and quantify Holocene summer-temperature fluctuations in the European Alps. Chironomid and pollen records indicate five centennial-scale cooling episodes during the early- and mid-Holocene. The strongest temperature declines of approximate to1degreesC are inferred at approximate to10,700-10,500... |
Proceedings of the National Academy of Sciences of the United States of America |
Departement Umweltwissenschaften / Geoökologie (Heiri) |
Heiri, Oliver; Millet, Laurent |
2005 |
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A chironomid–July air temperature inference model based on chironomid assemblages in the surface sediments of 81 Swiss lakes was used to reconstruct Late Glacial July air temperatures at Lac Lautrey (Jura, Eastern France). The transfer‐function was based on weighted averaging–partial least squares (WA‐PLS) regression and featured a leave‐one‐out... |
Journal of Quaternary Science |
Departement Umweltwissenschaften / Geoökologie (Heiri) |
Wagner, Bernd; Heiri, Oliver; Hoyer, Doreen |
2005 |
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A 2.6 m long sediment sequence from a small lake on Geographical Society Ø, central East Greenland, was investigated for chronology, lithology, biogeochemistry, and fossil chironomid assemblages. The sediment sequence comprises the complete lake history since the deglaciation of the area. Based on earlier investigations of the same sediment sequence, the lacustrine sedimentation without... |
Zeitschrift der Deutschen Gesellschaft für Geowissenschaften |
Departement Umweltwissenschaften / Geoökologie (Heiri) |
Peyron, O.; Bégeot, C.; Brewer, S.; Heiri, O.; Magny, M.; Millet, L.; Ruffaldi, P.; Van Campo, E.; Yu, G. |
2005 |
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High-temporal resolution analyses of pollen, chironomid, and lake-level records from Lake Lautrey provide multi-proxy, quantitative estimates of climatic change during the Late-Glacial period in eastern France. Past temperature and moisture parameters were estimated using modem analogues and 'plant functional types' transfer-function methods for three pollen records obtained from different... |
Quaternary research |
Departement Umweltwissenschaften / Geoökologie (Heiri) |
Bigler, Christian; Heiri, Oliver; Krskova, Renata; Lotter, André F.; Sturm, Michael |
2006 |
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Surface sediments from 30 mountain lakes in south-eastern Switzerland (Engadine, Grisons) were analysed for subfossil diatom, chironomid, and cladoceran assemblages. Ordination techniques were used to identify relevant physical and chemical environmental parameters that best explain the distribution of these biota in the studied lakes. Diatom assemblage composition showed a strong relationship... |
Aquatic Sciences |
Departement Umweltwissenschaften / Geoökologie (Heiri) |
Heiri, C.; Bugmann, H.; Tinner, W.; Heiri, O.; Lischke, H. |
2006 |
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1 We used the forest succession model FORCLIM simulate Holocene treeline dynamics along an elevational transect in the Central European Alps, in order to explore the extent and cause of changes in treeline altitude and composition. 2 A temperature reconstruction independent of vegetation proxies was used to drive the model, and the simulation results were compared with Holocene pollen and... |
Journal of Ecology |
Departement Umweltwissenschaften / Geoökologie (Heiri) |
Heiri, Oliver; Lotter, André F. |
2007 |
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The larval head capsules of Sciaridae (black fungus gnats) are transported into lakes from terrestrial habitats, in most cases via streams or rivers, and preserve well in lake sediments. The abundance of sciarid remains can provide information on the importance of terrestrial and running-water input into fossil insect assemblages in lake sediments if examined in relation to the number of fossils... |
Journal of Paleolimnology |
Departement Umweltwissenschaften / Geoökologie (Heiri) |
Beer, Ruth; Heiri, Oliver; Tinner, Willy |
2007 |
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Analyses of pollen, microscopic charcoal, loss on ignition (LOI) and chironomids in the sediment of the small sub-alpine lake Kichikol ( 2541 m a.s.l; 39 degrees 59'N, 73 degrees 33'E; Alay Range, Kyrgyzstan) provide new data to reconstruct the vegetational and lacustrine history during the past 6300 years. From 6300-5100 calibrated C-14 years BP (cal. yr BP) semi-deserts with Chenopodiaceae and... |
Holocene |
Departement Umweltwissenschaften / Geoökologie (Heiri) |
Heiri, Oliver; Cremer, Holger; Engels, Stefan; Hoek, Wim Z.; Peeters, Willem; Lotter, André F. |
2007 |
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Lateglacial environments at Hijkermeer, northwest Netherlands, were reconstructed by means of chironomid, diatom and pollen analyses. Diatom assemblages indicate that Hijkermeer was a shallow, oligo- to mesotrophic lake during this period. Pollen assemblages reflect the typical northwest European Lateglacial vegetation development and provide an age assessment for the record from the beginning of... |
Quaternary Science Reviews |
Departement Umweltwissenschaften / Geoökologie (Heiri) |
Helmens, K. F.; Bos, J. A. A.; Engels, S.; Van Meerbeeck, C. J.; Bohncke, S. J. P.; Renssen, H.; Heiri, O.; Brooks, S. J.; Seppä, H.; Birks, H. J. B.; Wohlfarth, B. |
2007 |
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Scandinavia is generally considered to have been covered extensively with ice throughout marine isotope stages (MIS) 4-2 between 75 and 10 ka. Here we present evidence for ice-free, warm conditions in the central area of the Scandinavian glaciations during MIS 3. Our multiproxy data obtained from a lacustrine sequence in northern Finland reveal not only significant response in the northeastern... |
Geology |
Departement Umweltwissenschaften / Geoökologie (Heiri) |
Cremer, Holger; Heiri, Oliver; Wagner, Bernd; Wagner-Cremer, Friederike |
2007 |
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We report a centennial-scale warming event between 8600 and 8400 cal BP from Amery Oasis, East Antarctica, that is documented by the geochemical record in a lacustrine sediment sequence. The organic carbon content, the C/S ratio, and the sedimentation rate in this core have distinctly elevated values around 8500 y ago reflecting relatively warm and ice-free conditions that led to well-ventilated... |
Quaternary Science Reviews |
Departement Umweltwissenschaften / Geoökologie (Heiri) |
