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A calibration data set, consisting of pollen assemblages from lake sediments dating from around AD 1800, and land cover on historical maps from the same period has been collected. 30 lakes between 3.5 and 30 ha in area, from different parts of Denmark were selected as calibration sites. This dataset has been used to analyse quantitative relationships between pollen assemblages and landcover, to estimate the relevant source area of pollen (Sugita, 1994) for small Danish lakes, to provide an empirical validation of the POLLSCAPE model (Davis, 2000; Sugita, 1993; Sugita et al., 1997) for simulating pollen sedimentation from a vegetation map, and to apply and test models for reconstructing landcover from pollen assemblages. The historical analogues approach was chosen, because extensive changes in the Danish cultural landscape during the past two hundred years has made it impossible to find analogues for older cultural landscape, at least of the spatial scale reflected by pollen assemblages from lake sediments (Nielsen and Odgaard, 2004; Odgaard and Rasmussen, 1998; Odgaard and Rasmussen, 2000).
Summary of results so far
The POLLSCAPE model was used to simulate pollen deposition in the calibration lakes from the historical plant abundance, and the simulated pollen proportions were compared to those observed in the lake sediments. Two sets of pollen productivity estimates, from southern Sweden (Broström, 2002; Sugita et al., 1999) and western Norway (Hjelle, 1998) were used in the simulations. For most taxa, there was a positive correlation between simulated and observed pollen proportions. The closest relationship between observed and predicted values was obtained using only 4 taxa (Trees, Poaceae, Cerealia and Calluna), because these were easiest to quantify based on the land cover signatures on the maps. Estimates of pollen productivity and background term using ERV submodel 2 are applied to the AD 1800 pollen counts from nine test sites, which are not included in the calibration dataset, and distance weighted plant abundance around these sites is reconstructed using the inverse form of ERV submodel 2. Reconstructed distance weighted plant abundance is compared to that estimated from historical maps. 
Ongoing work
The Landscape Reconstruction Algorithm proposed by (Sugita and Walker, 2000) will be tested on the data. This involves counting pollen assemblages from a number of large lakes (over 1 km2), and using these to estimate regional pollen loading in different parts of the country, because this contributes to the pollen sedimentation in the smaller lakes, as well as the local vegetation. If successful, this approach will allow quantitative vegetation reconstruction for periods in the past, based on pollen records from large and small basins. This, more detailed quantitative interpretation of late Holocene pollen diagrams than is currently possible will hopefully lead to a better understanding of the history of the cultural landscape. The work is a contribution to the NORFA funded network POLLANDCAL ( www.geog.ucl.ac.uk/ecrc/pollandcal/
References
Hjelle, K.L., 1998. Herb pollen representation in surface moss samples from mown meadows and pastures in western Norway. Vegetation History and Archaeobotany 7 , 79-96. Nielsen, A.B., 2003. Pollen based quantitative estimation of land cover - Relationships between pollen sedimentation in lakes and land cover as seen on historical maps in Denmark AD 1800, Danmarks og Grønlands Geologiske Undersøgelse Rapport 2003/57. GEUS, Copenhagen, 135 pp. Nielsen, A.B., & Odgaard, B., 2004. The use of historical analogues for interpreting fossil pollen records. Vegetation History and Archaeobotany 13 (1), 33-43. Odgaard, B.V., & Rasmussen, P., 1998. The use of historical data and sub-recent (A.D. 1800) pollen assemblages to quantify vegetation/pollen relationships. In: Gaillard, M.-J., Berglund, B. (Editors). Paläoklimaforschung. Gustav Fischer Verlag, 67-75. Odgaard, B.V., & Rasmussen, P., 2000. Origin and temporal development of macro-scale vegetation patterns in the cultural landscape of Denmark. Journal of Ecology 88 , 733-748. Sugita, S., 1993. A Model of Pollen Source Area for an Entire Lake Surface. Quaternary Research, 39(2): 239-244. Sugita, S., 1994. Pollen representation of vegetation in Quaternary sediments: Theory and method in patchy vegetation. Journal of Ecology 82 , 881-897. Sugita, S., Gaillard, M.-J., & Broström, A., 1999. Landscape openness and pollen records: A simulation approach. The Holocene 9 (4), 409-421. Sugita, S., MacDonald, G.M., & Larsen, C.P.S., 1997. Reconstruction of fire disturbance and forest succession from fossil pollen in lake sediments: Potential and limitations. In: Clark, J.S., Cachier, H., Goldammer, J.G., Stocks, B.J. (Editors), Sediment records of biomass burning and global change. Springer-Verlag, Berlin 387-412 pp. Sugita, S., & Walker, K., 2000. Landscape Reconstruction Algorithm for estimating vegetation changes from pollen records: A case study in the Upper Great Lakes region using modern and presettlement pollen-vegetation data sets., AGU Fall Meeting, San Fransisco.
PhD working title 'Holocene paleo-hydrographic changes in Greenland coastal waters and fjords, and possible implications for human settlement.'
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The aims of the project are two-fold:
While global annual average temperature has been steadily rising since the early 1980's, a cooling trend in West Greenland temperature records has been observed during the last decade. This adds to the records of slight cooling in the Labrador Sea and southern Greenland since the 1960's. Since the mid 1980's, changes have been observed in the North Atlantic deep water formation; a cessation of convective deep water renewal has been reported in the Greenland Sea, and convection has started to prevail in the Labrador Sea. These areas off Greenland are, apart from Antarctic waters, the only sites with direct exchange between the atmosphere and the deep ocean. Palaeoceanographic studies and coupled atmosphere-ocean models indicate that climate changes in the North Atlantic region are closely related to changes in surface circulation and in the production of North Atlantic deep water. In this project cores will be taken from south-west and west Greenland in order to compare regional hydrographic patterns. The Ph.D.-project will take a multi-proxy palaeoceanographic approach using diatoms, stable isotopes as well as other relevant geo-chemical and sedimentological records from high-resolution sediment cores. Diatoms are sensitive to environmental changes, e.g. salinity, temperature and nutrients, and therefore valuable indicators when determining the hydrographic conditions. As salinity and sea surface temperatures can provide hydrographic proxies, the project attempts to reconstruct past changes in sea surface temperature and salinity by the application of diatom-based transfer functions. Through comparison with Greenland lake- and ice core data, the work will contribute to a better understanding of atmosphere-ocean interaction and long-term climate patterns of the seas around Greenland. Comparison with relevant Holocene climate records from north-west Europe may help explaining the interrelationship between the cooling trend observed on Greenland and documented global (Northwest European) warming.
The record of Paleo-Eskimo cultures on Greenland's west coast shows various major immigration and cultural stages of which the initial phase of the oldest (Saqqaq) culture has been dated at near 4,3 ka. In addition, the southwards expansion of the Thule culture coincided with the beginning of the Little Ice Age, 1200-1300 AD. Archaeological evidence from Western Canada and eastern North America shows much earlier human occupation of high-latitude areas, i.e. at the Pleistocene-Holocene boundary. It thus seems that the Holocene southward migration of Inuit in Greenland occurred when Holocene climate deteriorated, i.e. in Middle Holocene times and at the beginning of the Little Ice Age. This may be coincidence, or might be related to changes of the (marine) physical environment directly affecting resource utilisation. The further objective of this project is to establish a highly detailed (AMS C-14) chronology focusing on Mid-Holocene and Little Ice Age-related hydrographic changes that could have implications for the Eskimo and Norse settlement stages. In order to study possible links between these changes and the physical (marine) environment and human settlement history, extensive dating of archaeological material is envisaged as well.
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The thrust complex consists of disturbed, folded and thrusted sediments sliding on a weakly inclined basal décollement surface. The layers beneath the basal décollement surface are undisturbed; thus the thrust complex is interpreted as a glaciotectonic thrust complex. The dimensions of the thrust complex is one of its kind, with thrust sheets varying in length from less than 100 m till more than 1,5 km. The thrust faults emerge from depths down to 375 m, and the whole thrust complex covers an area of more than 15 km times 40 km. Correlation with the well S-1 in the Danish part of the North Sea indicates that the décollement surface is located in the Mid Miocene. The north-south striking deformation front is situated 35 km from the west coast of Jutland. Similarities with the onshore geology are being investigated in order to place the complex into a regional glaciostratigraphic context. The methods include mapping of glaciotectonically dislocated Miocene deposits onshore and lithostratigraphic analysis of a till unit in the Rømø-2 well. In this particular geological site in the SE Danish North Sea it is possible to obtain an unprecedented insight in a glaciogenic thrust fault system. Mapping and understanding of the thrust structures is expected to provide a significant contribution to the conception of similar features in the North Sea. Furthermore, the study will contribute to the regional geological interpretation of the Miocene offshore and onshore, and thus provide insight of importance for e.g. hydrogeological investigations.
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Previous research documents glacier observation and glacier stand for scattered localities in southern Greenland over the past 100 years. Here the study will use information conveyed by different sources to establish a physical history of glacier response behaviour. The historical and present changes of the southern Greenland ice sheet will be examined by ice-sheet margin observation using a combination of airborne photographs and satellite images in order to determine the historical glacier positions over the last decades. The historical and present investigation of the ice-margin fluctuation will be used to evaluate the results from the ice-dynamic model. This project is linked to the IMERSUAQ project as well as to the EuroClim and Cryosat project
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The first find of annually laminated (varved) Holocene lake sediments in a Danish site - Sarup Sø (Rasmussen et al., 2002) - presents exciting possibilities for palaeoecological and palaeoclimatological studies. The research is in collaboration with Bent Vad Odgaard, University of Aarhus. Bent leads a multi-disciplinary project to study the Sarup Sø varves, funded by the Danish Research Council for Natural Sciences. Emily Bradshaw's project aims are i) to assist in the establishment of a varve chronology for the site and ii) to explore changes in the aquatic ecosystem, prior to major human impacts at the site, and so influenced only by natural external (e.g. climatic) and internal (e.g. biological) processes, using diatom, biogenic silica, and palaeo-pigment analyses.
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