German Archaeological Institute DAI

Berlin, Germany

German Archaeological Institute DAI

Berlin, Germany

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Dinies M.,German Archaeological Institute DAI | Dinies M.,Free University of Berlin | Plessen B.,German Research Center for Geosciences | Neef R.,German Archaeological Institute DAI | Kurschner H.,Free University of Berlin
Quaternary International | Year: 2015

An early-to-mid Holocene lake in the north of the oasis of Tayma, northwestern Saudi Arabia, proved to be an excellent palynological archive. A shallow, probably brackish water body formed at about 9200 cal BP, with the dominance of goosefoot throughout the sequence indicating the persistence of desert vegetation. However, distinct vegetation changes are recorded during the early Holocene. Grasslands spread soon after 9000 cal BP and reached their maximal expansion ca 8600-8000 cal BP. At about 8000 cal BP these grasslands retreated abruptly and were replaced by more drought-resistant dwarf-shrublands, similar to the present-day ecosystems. The recorded early Holocene grassland expansion furnishes for the first time evidence of an additional and more favourable grazing resource, and thereby improved conditions for herders/hunters, during the Early Holocene in northwestern Arabia, which retreated abruptly due to aridification at about 8000 cal BP. © 2015 Elsevier Ltd and INQUA.


Kaiser K.,German Research Center for Geosciences | Heinrich I.,German Research Center for Geosciences | Heine I.,German Research Center for Geosciences | Natkhin M.,Thunen Institute of Forest Ecosystems | And 8 more authors.
Journal of Hydrology | Year: 2015

In the glacially formed landscape of north-eastern Germany pronounced hydrological changes have been detected in recent decades, leading to the general question how lake levels and related groundwater levels perform in a long-term perspective, i.e. during the last c. 100. years. But long-term lake-level records are rare; most observations do not start before the late 20th century. Therefore, the potential of historic hydrological data, comprising drowned trees (as a geo-/bioarchive) and aerial as well as map imagery (as a document archive) was tested in order to derive discrete-time lake-level stands. These data are contrasted with lake-level simulations, obtaining a continuous-time series.Two small glacial lakes without connection to the stream network (i.e. closed lakes) were investigated in the Schorfheide area, c. 70. km north of Berlin. Both are dominantly fed by groundwater and precipitation but differ in their hydrogeological and catchment characteristics. For one lake a c. 40. year-long gauging record is available, showing high lake levels in the 1980s followed by a lowering of c. 3. m till the mid-2000s. In both lakes submerged in situ tree remains were discovered and dated by dendrochronology, revealing low lake levels during the first half of the 20th century. One lake was almost completely dry until c. 1960. Aerial photos provided data on lake levels since the 1930s which are corroborated by evidence of topographic mapping. Combining the empiric data with retrograde lake-level modelling, a well-proven lake-level record can be established for one lake that covers the last c. 90. years. The same general lake-level dynamics could be reconstructed by means of proxy data for the other lake. In both cases climate has been the dominant driver of lake-level dynamics. Comparisons with other multi-decadal lake-level records from the region show that these differ, depending on the hydrological lake type which modifies water feeding and water level. The results clearly showed that lake levels exhibited substantial long-term changes that should be taken into account in future hydroclimatic and hydrological studies. © 2015 Elsevier B.V.


Pieper H.,German Research Center for Geosciences | Heinrich I.,German Research Center for Geosciences | Heussner K.U.,German Archaeological Institute DAI | Helle G.,German Research Center for Geosciences
Palaeogeography, Palaeoclimatology, Palaeoecology | Year: 2014

Palaeoclimate proxies have shown links between climate changes and volcanic activity. However, not much is known about the impact of volcanic outbursts on growth of lowland trees. We investigate the effect of large volcanic eruptions on the growth rate of trees. The study is based on an unexplored comprehensive database with 1128 samples of long tree-ring width (TRW) chronologies of Quercus robur L. and Pinus sylvestris L., correlating with forest net primary production (NPP), originating from three different sites in eastern Germany (Greifswald, Eberswalde and Saxony). This study focuses on trees in rarely examined temperate zones where tree growth is less temperature limited. Growth relationships were compared against 52 large volcanic eruptions known for the last 1000. years. Dendrochronological methods revealed a predominantly negative (60.2%) effect of large volcanic eruptions on the tree-ring chronologies. Nevertheless, also positive (31.7%) and neutral (8.7%) tree growth reactions were detected. In the tree-ring width chronologies of Q. robur and P. sylvestris, we detected a negative influence on tree growth for up to four years after large eruptions. The chronologies of Q. robur revealed a stronger negative response (68.1%) than those of P. sylvestris (53%). However, at the Greifswald site both tree species (79% Q. robur and 73% P. sylvestris) show a negative response in tree growth after every volcanic eruption. Furthermore, the results suggest that volcanic aerosols originating from the Northern Hemisphere cause a greater reduction in tree growth than aerosols being emitted from Southern Hemisphere volcanoes, which might be related to the long distances between trees and volcanoes, as well as the global atmospheric circulation patterns. This study demonstrates that the effects of major volcanic eruptions are less clear in trees from central European lowlands than in trees growing at the altitudinal or latitudinal timberlines. © 2014 Elsevier B.V.


PubMed | Anglia, Navarino Environmental Observatory, National Museum of Denmark, Lamont Doherty Earth Observatory and 35 more.
Type: Journal Article | Journal: Science advances | Year: 2015

Climate model projections suggest widespread drying in the Mediterranean Basin and wetting in Fennoscandia in the coming decades largely as a consequence of greenhouse gas forcing of climate. To place these and other Old World climate projections into historical perspective based on more complete estimates of natural hydroclimatic variability, we have developed the Old World Drought Atlas (OWDA), a set of year-to-year maps of tree-ring reconstructed summer wetness and dryness over Europe and the Mediterranean Basin during the Common Era. The OWDA matches historical accounts of severe drought and wetness with a spatial completeness not previously available. In addition, megadroughts reconstructed over north-central Europe in the 11th and mid-15th centuries reinforce other evidence from North America and Asia that droughts were more severe, extensive, and prolonged over Northern Hemisphere land areas before the 20th century, with an inadequate understanding of their causes. The OWDA provides new data to determine the causes of Old World drought and wetness and attribute past climate variability to forced and/or internal variability.


Buntgen U.,Swiss Federal Institute of forest | Buntgen U.,Oeschger Center for Climate Change Research | Brazdil R.,Masaryk University | Brazdil R.,Academy of Sciences of the Czech Republic | And 7 more authors.
Quaternary Science Reviews | Year: 2011

A predicted rise in anthropogenic greenhouse gas emissions and associated effects on the Earth's climate system likely imply more frequent and severe weather extremes with alternations in hydroclimatic parameters expected to be most critical for ecosystem functioning, agricultural yield, and human health. Evaluating the return period and amplitude of modern climatic extremes in light of pre-industrial natural changes is, however, limited by generally too short instrumental meteorological observations. Here we introduce and analyze 11,873 annually resolved and absolutely dated ring width measurement series from living and historical fir (Abies alba Mill.) trees sampled across France, Switzerland, Germany, and the Czech Republic, which continuously span the AD 962-2007 period. Even though a dominant climatic driver of European fir growth was not found, ring width extremes were evidently triggered by anomalous variations in Central European April-June precipitation. Wet conditions were associated with dynamic low-pressure cells, whereas continental-scale droughts coincided with persistent high-pressure between 35 and 55°N. Documentary evidence independently confirms many of the dendro signals over the past millennium, and further provides insight on causes and consequences of ambient weather conditions related to the reconstructed extremes. A fairly uniform distribution of hydroclimatic extremes throughout the Medieval Climate Anomaly, Little Ice Age and Recent Global Warming may question the common believe that frequency and severity of such events closely relates to climate mean stages. This joint dendro-documentary approach not only allows extreme climate conditions of the industrial era to be placed against the backdrop of natural variations, but also probably helps to constrain climate model simulations over exceptional long timescales. © 2011 Elsevier Ltd.


Buntgen U.,Swiss Federal Institute of forest | Buntgen U.,Oeschger Center for Climate Change Research | Buntgen U.,Academy of Sciences of the Czech Republic | Tegel W.,Albert Ludwigs University of Freiburg | And 19 more authors.
Frontiers in Ecology and the Environment | Year: 2014

Forest decline played a pivotal role in motivating Europe's political focus on sustainability around 35 years ago. Silver fir (Abies alba) exhibited a particularly severe dieback in the mid-1970s, but disentangling biotic from abiotic drivers remained challenging because both spatial and temporal data were lacking. Here, we analyze 14 136 samples from living trees and historical timbers, together with 356 pollen records, to evaluate recent fir growth from a continent-wide and Holocene-long perspective. Land use and climate change influenced forest growth over the past millennium, whereas anthropogenic emissions of acidic sulfates and nitrates became important after about 1850. Pollution control since the 1980s, together with a warmer but not drier climate, has facilitated an unprecedented surge in productivity across Central European fir stands. Restricted fir distribution prior to the Mesolithic and again in the Modern Era, separated by a peak in abundance during the Bronze Age, is indicative of the long-term interplay of changing temperatures, shifts in the hydrological cycle, and human impacts that have shaped forest structure and productivity. © The Ecological Society of America.


Buntgen U.,Swiss Federal Institute of forest | Buntgen U.,Oeschger Center for Climate Change Research | Tegel W.,Albert Ludwigs University of Freiburg | Heussner K.-U.,German Archaeological Institute DAI | And 4 more authors.
Climate Research | Year: 2012

Uncertainty related to the rate and magnitude of predicted anthropogenic climate change highlights the need to enhance our understanding of past natural fluctuations in the Earth's climate system. This task emphasizes the importance of high-resolution palaeoclimatic records that cover industrial and pre-industrial times. Annually resolved and absolutely dated tree-ring measurements are a key input for cross-disciplinary research. Ambiguity due to paucity of data, however, characterizes many tree-ring data analyses. By utilizing nearly 12 000 living and historical ring width series from European fir Abies alba Mill., we demonstrate how massive sample replication can generate robust estimates of past growth rates, which may help reduce methodological and statistical constraints associated with many traditional tree-ring studies. © Inter-Research 2012.


Wild E.M.,University of Vienna | Steier P.,University of Vienna | Fischer P.,Gothenburg University | Hoflmayer F.,German Archaeological Institute DAI
Radiocarbon | Year: 2013

Radiocarbon dating of plant remains is often difficult due to the complete dissolution of the samples in the alkaline step of the ABA pretreatment. At the VERA laboratory, this problem was encountered frequently when numerous Bronze and Early Iron Age samples from the eastern Mediterranean were dated in the course of the special research program SCIEM2000 and in other collaborations with archaeologists focused on that area and time period. For these samples, only a 14C age determination of the humic acid fraction was possible. Humic acids from archaeological samples are always assessed as a second-choice material for 14C dating. It is assumed that the 14C ages may be affected by the presence of humic acids originating from other (younger) organic material, e.g. from soil horizons located above a sample. Therefore, when humic acids are dated a verification of the dates is crucial. To address this basic requirement, we started some time ago to date both fractions of charred seeds, wood, and charcoal samples whenever available, i.e. the residue after the ABA treatment and the humic acids extracted from the samples in the alkaline step. The results of this comparison showed that for the investigated eastern Mediterranean archaeological sites, 50 (out of 52) humic acid dates were in agreement with the 14C dates of the respective ABA-treated samples. Statistical analysis of the age differences leads to the conclusion that the extracted humic acids originated from the samples themselves or from contemporaneous material and were not appreciably contaminated by extraneous material of different age. © 2013 by the Arizona Board of Regents on behalf of the University of Arizona.


Seeliger M.,University of Cologne | Bartz M.,University of Cologne | Erkul E.,University of Kiel | Feuser S.,University of Rostock | And 5 more authors.
Quaternary International | Year: 2013

During Hellenistic times, when the Pergamenian kingdom was prospering, Pergamum was operating an important harbour, used by merchants and military at the city of Elaia. This paper focuses on the development, utilisation and decay of the closed harbour of Elaia, which is discussed in the context of the landscape evolution of the environs of the ancient settlement. Based on geoarchaeological, archaeological and literary evidence, the construction of two harbour moles in order to provide shelter against wave action and enemies can be attributed to the early Hellenistic period. Geoelectric measurements revealed the construction profile of the moles. Coring evidence indicated that together with mole construction, a greater area of the formerly shallow marine and sublittoral terrain was consolidated, most probably to create space for harbour installations. The closed harbour basin was used intensely during Hellenistic and Roman times. Later, continued siltation hindered further usage. In combination with the decline of the city of Elaia in Late Antiquity, this was the reason why the harbour was abandoned. Scenarios for the time of the maximum transgression of the sea around 2500 BC, the early Hellenistic times around 300 BC, and Late Antiquity AD 500, are presented. © 2013 Elsevier Ltd and INQUA.

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