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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Vegetationshistoria de senaste 5000 åren kring Fållnäs gård, Södermanland : med tyngdpunkt på antropogena aktiviteter

Liljedahl, Hanna January 2009 (has links)
<p>The manor Fållnäs gård is situated at the northern end of the bay Fållnäsviken, c. 12 km north-west of Nynäshamn, Sweden. A 300 cm long sediment core collected in the bay has been analyzed regarding pollen stratigraphy. AMS <sup>14</sup>C dating of terrestrial macrofossils indicates that the sequence covers the last c. 5400 years.</p><p>The aim has been to study vegetational changes, especially human impact, in the surroundings of Fållnäs gård. Continuous findings of charcoal particles indicate that humans were present in the area at least from c. 3400 BC. Cattle breeding is indicated from c. 2200 BC by almost continues occurrences of <em>Plantago lanceolata</em>. The occurrences of pollen from cereals reveals that humans have been practicing cultivation continuously since the Neolithic/Bronze Age transition, c. 1700 BC, i.e. including a period of c. 1500 years barren of archaeological findings in the area.</p>
2

Vegetationshistoria de senaste 5000 åren kring Fållnäs gård, Södermanland : med tyngdpunkt på antropogena aktiviteter

Liljedahl, Hanna January 2009 (has links)
The manor Fållnäs gård is situated at the northern end of the bay Fållnäsviken, c. 12 km north-west of Nynäshamn, Sweden. A 300 cm long sediment core collected in the bay has been analyzed regarding pollen stratigraphy. AMS 14C dating of terrestrial macrofossils indicates that the sequence covers the last c. 5400 years. The aim has been to study vegetational changes, especially human impact, in the surroundings of Fållnäs gård. Continuous findings of charcoal particles indicate that humans were present in the area at least from c. 3400 BC. Cattle breeding is indicated from c. 2200 BC by almost continues occurrences of Plantago lanceolata. The occurrences of pollen from cereals reveals that humans have been practicing cultivation continuously since the Neolithic/Bronze Age transition, c. 1700 BC, i.e. including a period of c. 1500 years barren of archaeological findings in the area.
3

Present and Past Coastal Dune Environments of South Buenos Aires Province, Argentina

Fontana, Sonia L. January 2004 (has links)
<p>The aim of this thesis is to describe present and past coastal dune environments in southern Buenos Aires Province, Argentina. </p><p>The present vegetation of a dune system and its zonation are described on the basis of air photographs, physiognomy of the dune system and floristic composition. The vegetation was characterized by a large number of Poaceae and Asteraceae species. Five vegetation zones, based on floristic composition, were defined by cluster analysis. </p><p>Pollen-vegetation comparison revealed that pollen assemblages differed considerably from the associated vegetation. Some of the major discrepancies were caused by large differences between pollen and vegetation proportion of <i>Hyalis argentea</i> and <i>Discaria americana</i>. However, the local vegetation was well represented in recent soil samples. Pollen traps recorded predominantly extralocal and regional pollen. </p><p>A new species of ostracods was recovered from an interdunal lake. The species, a giant cypridid, was described and illustrated, and its geographical distribution and ecology were discussed. </p><p>Two sediment sequences from the coastal intertidal zone and from a shallow freshwater lake were analysed for loss on ignition, calcareous microfossils (ostracods and foraminifers), macro remains and pollen. The coastal sequence was deposited between 7890 and 7630 cal. BP. Its pollen assemblages were typical for halophytic associations, with some psammophytic taxa also present in recent vegetation. The microfossils were representative of a littoral lagoon. The lake sequence comprised the last 3000 cal. BP. Pollen spectra indicated a relatively stable vegetation composition after the lake had been formed. Pollen assemblages reflected the present regional grassland vegetation with taxa characteristic for the surrounding dune communities. Human settlement was indicated in the pollen spectra by the presence of introduced taxa in the uppermost samples. </p><p>The data presented provide a useful reference for the interpretation of fossil sequences from similar environments.</p>
4

The Holocene Spread of Spruce in Scandinavia

Giesecke, Thomas January 2004 (has links)
<p>The Holocene spread of <i>Picea abies</i> in Scandinavia provides an excellent opportunity for detailed study of the dynamics of tree spread and population expansion. Early- and mid-Holocene macrofossil evidence for the presence of <i>Picea abies</i> in Scandinavia has questioned traditional interpretations of the timing and direction of its spread. This study aims to determine the pattern of the spread of <i>Picea abies</i> in Scandinavia from pollen and other data, to evaluate the significance of possible early outpost populations and to deduce possible factors that influenced the spread and population expansion of <i>Picea abies</i> in Scandinavia. </p><p>Palaeoecological investigations were carried out on the sediments of four small lakes in central Sweden to gain detailed insight into the dynamics of the spread. Holocene pollen diagrams with independent dating control were collected from Fennoscandia and adjacent areas to compare the timing of selected features of the <i>Picea abies</i> pollen curve. Computer models were used to test possible scenarios for the spread and <i>Picea abies</i> population expansion. </p><p><i>Picea abies</i> entered the Scandinavian peninsula from the east at different times and by different pathways. Early-Holocene outposts can be discerned in pollen records from northwest Russia, eastern and northeastern Finland for the time before 9000 cal. BP. Pollen records from Sweden and Norway indicate small <i>Picea abies</i> populations after 8000 cal. BP. The mid to late-Holocene spread, which superficially resembles a front-like pattern, may in fact represent a wave of expanding populations. Disturbance through fire and human activity did not significantly influence the pattern of the spread. Changing climate parameters, slow adaptation and gene flow through seeds and pollen have to be considered as possible explanations for the late spread of the tree. Population dynamics and propagule pressure are likely to be important factors that shaped the spread of <i>Picea abies</i>.</p>
5

Present and Past Coastal Dune Environments of South Buenos Aires Province, Argentina

Fontana, Sonia L. January 2004 (has links)
The aim of this thesis is to describe present and past coastal dune environments in southern Buenos Aires Province, Argentina. The present vegetation of a dune system and its zonation are described on the basis of air photographs, physiognomy of the dune system and floristic composition. The vegetation was characterized by a large number of Poaceae and Asteraceae species. Five vegetation zones, based on floristic composition, were defined by cluster analysis. Pollen-vegetation comparison revealed that pollen assemblages differed considerably from the associated vegetation. Some of the major discrepancies were caused by large differences between pollen and vegetation proportion of Hyalis argentea and Discaria americana. However, the local vegetation was well represented in recent soil samples. Pollen traps recorded predominantly extralocal and regional pollen. A new species of ostracods was recovered from an interdunal lake. The species, a giant cypridid, was described and illustrated, and its geographical distribution and ecology were discussed. Two sediment sequences from the coastal intertidal zone and from a shallow freshwater lake were analysed for loss on ignition, calcareous microfossils (ostracods and foraminifers), macro remains and pollen. The coastal sequence was deposited between 7890 and 7630 cal. BP. Its pollen assemblages were typical for halophytic associations, with some psammophytic taxa also present in recent vegetation. The microfossils were representative of a littoral lagoon. The lake sequence comprised the last 3000 cal. BP. Pollen spectra indicated a relatively stable vegetation composition after the lake had been formed. Pollen assemblages reflected the present regional grassland vegetation with taxa characteristic for the surrounding dune communities. Human settlement was indicated in the pollen spectra by the presence of introduced taxa in the uppermost samples. The data presented provide a useful reference for the interpretation of fossil sequences from similar environments.
6

The Holocene Spread of Spruce in Scandinavia

Giesecke, Thomas January 2004 (has links)
The Holocene spread of Picea abies in Scandinavia provides an excellent opportunity for detailed study of the dynamics of tree spread and population expansion. Early- and mid-Holocene macrofossil evidence for the presence of Picea abies in Scandinavia has questioned traditional interpretations of the timing and direction of its spread. This study aims to determine the pattern of the spread of Picea abies in Scandinavia from pollen and other data, to evaluate the significance of possible early outpost populations and to deduce possible factors that influenced the spread and population expansion of Picea abies in Scandinavia. Palaeoecological investigations were carried out on the sediments of four small lakes in central Sweden to gain detailed insight into the dynamics of the spread. Holocene pollen diagrams with independent dating control were collected from Fennoscandia and adjacent areas to compare the timing of selected features of the Picea abies pollen curve. Computer models were used to test possible scenarios for the spread and Picea abies population expansion. Picea abies entered the Scandinavian peninsula from the east at different times and by different pathways. Early-Holocene outposts can be discerned in pollen records from northwest Russia, eastern and northeastern Finland for the time before 9000 cal. BP. Pollen records from Sweden and Norway indicate small Picea abies populations after 8000 cal. BP. The mid to late-Holocene spread, which superficially resembles a front-like pattern, may in fact represent a wave of expanding populations. Disturbance through fire and human activity did not significantly influence the pattern of the spread. Changing climate parameters, slow adaptation and gene flow through seeds and pollen have to be considered as possible explanations for the late spread of the tree. Population dynamics and propagule pressure are likely to be important factors that shaped the spread of Picea abies.
7

Palaeoglaciology of the northeastern Tibetan Plateau

Heyman, Jakob January 2010 (has links)
This study concerns the palaeoglaciation of the northeastern Tibetan Plateau, with emphasis on the Bayan Har Shan (Shan = Mountain) in the headwaters of Huang He (Yellow River). To reconstruct past glacier development multiple techniques, including remote sensing, field investigations, cosmogenic exposure dating, and numerical modelling have been employed. Analysis of the large-scale geomorphology indicates that glacial erosion has been dominant in the elevated mountain areas on the low-relief plateau, whereas fluvial erosion outpaces glacial erosion along the plateau margin. Landform and sediment records yield evidence for multiple local glaciations, restricted to the highest mountain areas, and a maximum glaciation beyond the mountain front. Absence of data supporting the former presence of proposed ice sheets, plateau-wide or regional, tentatively indicates that no ice sheet glaciation occurred on the northeastern Tibetan Plateau. Cosmogenic exposure dating of boulders, surface pebbles, and sediment sections in central Bayan Har Shan indicates that its record of past glaciations predates the global Last Glacial Maximum (LGM). Based on a world-wide analysis, yielding that wide age disparity within apparent exposure age datasets is most likely caused by post-glacial shielding processes, the Bayan Har Shan exposure ages constrain four periods of glaciation with minimum ages of 40-65 ka, 60-100 ka, 95-165 ka, and undetermined oldest stage. Similar to Bayan Har Shan, the plateau-wide distribution of boulders with pre-LGM exposure ages close to present-day glaciers shows that its LGM glaciers were generally not much larger than today. The results of a high resolution glacier model applied to nine regions across the plateau indicates that temperature depressions of 2-4 K are enough to expand glaciers beyond their global LGM extent, implying that during periods of Northern Hemisphere glaciation the Tibetan Plateau was not much colder than today or became exceedingly dry. / At the time of doctoral defence the following publications were unpublished and had a status as follows: Paper 4: Manuscript. Paper 5: Manuscript.
8

Geovetenskaplig analfabetism i Sverige – En undersökning av allmänhetens och beslutsfattarnas kunskaper

Lundqvist, Jennie January 2013 (has links)
Earth science is a dynamic system science that explores the structures and processes of the earth. Knowledge about the earth is important for citizens since the science is a vital part in the sustainable development of the society. Without good basic knowledge the citizens don’t have the possibility to anticipate in the questions and decision-making that concerns e.g. anthropogenic climate change. In the Swedish school system earth science is not an independent subject until academically studies at the University’s. The purpose of this study is to investigate the level of knowledge among citizens and policymakers in Sweden and to find out if there is any illiteracy for earth science in Sweden. The method conducted of two web-based surveys and the questions in the surveys are focused around the subject of anthropogenic climate change because it is one of the most well known areas of earth science amongst the citizens. The survey results are based on 159 answers from each survey and shows that there is illiteracy for earth science in Sweden. It is also possible to se that the policymakers have better knowledge about earth science than the citizens. The results also show that there is a concern amongst the citizens regarding the effects that humans do to anthropogenic climate change. One solution to the illiteracy and worries amongst the public is better education in earth science. How to best teach a subject is developed in the research area of didactics but for earth science this is a relatively young science, in need of more research both in Sweden and internationally. / Geovetenskap är en dynamisk systemvetenskap som utforskar jordens utveckling och uppbyggnad. Geovetenskapliga kunskaper är vitala för det moderna hållbara samhället, men i Sverige finns ämnet geovetenskap bara som fristående ämne på akademisk nivå. Utan grundkunskaper har medborgarna inte lika stora möjligheter att delta i debatter och fatta beslut i frågor som exempelvis antropogena klimatförändringar. Syftet med denna studie är att undersöka det geovetenskapliga kunskapsläget i Sverige och om frånvaron av denna undervisning i skolan/gymnasiet kan orsaka geovetenskaplig analfabetism. Undersökningen genomfördes via två internetbaserade enkäter en riktade sig mot Sverige allmänhet och en mot tjänstemän/politiker. Frågorna i enkäterna byggdes upp kring antropogena klimatförändringar då detta område är mer allmänt känt än ämnet geovetenskap och de övrigt innefattande områdena. Resultatet från undersökningen baseras på 159 svar från respektive enkät och visar att det finns en geovetenskaplig analfabetism i båda undersökningsgrupperna. Det går att utläsa en liten skillnad i kunskapsnivå mellan de två undersökningsgrupperna, beslutsfattare/tjänstemän har en något högre kunskapsnivå än allmänheten. Resultaten visar också att det finns en oro bland allmänheten för olika effekter av klimatförändringar som att Golfströmmen kan stanna och att antalet tsunamivågor kan komma att öka. Dessutom tror en mindre del (16%) av allmänheten att jordbävningen i Chile 2010 orsakades av antropogena klimatförändringar. För att kunna förbättra de geovetenskapliga kunskapsnivåerna krävs utbildning av både barn och vuxna. Dessutom krävs det mer forskning i geovetenskaplig didaktik som är ett ungt och outforskat område både i Sverige och internationellt.
9

Inventering av Hårsbäcksdalen och Örsundaåns övre dalgång ur ett geodiversitetsperspektiv

Glansholm, Helena January 2011 (has links)
The area around the stream Orsundaan, which runs trough the valley Harsbacksdalen, is famous for its beautiful landscape. The upper area of Orsundaan and Harsbacksdalen is situated just south of Heby in Uppland, Sweden. Even though the area is protected by different nature conservation acts, it is difficult to find any information about the geodiversity in the area. Geodiversity, or geological and geomorphological diversity, includes the concepts of geoprocesses and geoelements. Very high geodiversity could be seen at an inventory of the geomorphology in the upper area of Orsundaan and Harsbacksdalen. Geodiversity in not only important for understanding the geological development of the landscape, which in turn can be connected to global climate changes, but it is also very important for the biodiversity in the area. Thus, it is of great importance that people working with nature conservation issues are familiar with the geodiversity in the area. This also applies to those working with development plans of the area. Furthermore, it is of interest that visitors will be given a chance to learn more about the landscape development of Harsbacksdalen and Orsundaan and for them to get an understanding of the geoprocesses and geoelements found in the area.
10

Glupförekomster i Uppsalaområdet

Hagström, Per January 2012 (has links)
One special feature in the Swedish nature, mainly in the county of Uppland is one distinctive kind of dip, which can be distinguished from its fast and unaccounted drainage. These dips are called “glupar” and can mainly be found in coarse-grained pebbled moraine under the highest shoreline (HK). During spring, and particularly when snowmelting occur, the wateramliptude fluctuates a lot until late summer or the beginning of fall comes; these dips are then often almost fully drained. During winter however, the waterlevel stands high. Therefore, “glupar” can for some time be falsely interpreted as a small pond. Areas around Jumkil just outside Uppsala are charaterized for their large amount of these kinds of dips. The origin of “glupar” is poorly studied or described through the literature, which to a large extent is the main reason for this study.

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