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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

A Record of Environmental and Climatic Change from the West Coast, South Island, New Zealand, using Beetle Fossils

Burge, Philip Ian January 2007 (has links)
Fossil beetle based palaeoclimatic and palaeoenvironmental reconstructions are presented from the Westport region, West Coast, South Island, New Zealand for the last glacial cycle. They include the longest continuous fossil beetle record from New Zealand, covering 16,000 years over the OIS 3/OIS 2 transition. Early last glacial (OIS 4) and mid- Holocene (OIS 1) reconstructions are also presented. The assumptions underlying fossil beetle research in New Zealand are tested indicating beetles are suitable proxies for reconstructing palaeotemperature and palaeoprecipitation. This thesis provides the first quantitative estimates of temperature and precipitation from the Westport region for the last glacial. Reconstructed temperatures indicate stadial cooling was seasonal. Maximum cooling was ca. 5℃ in winter and ca. 2-3℃ in summer. Winter cooling is consistent with previous quantitative estimates from New Zealand. Mean annual precipitation decreased a maximum 35-40% during stadials. Temperatures and precipitation varied during OIS 3/2 indicating multiple possible drivers for glaciation. A glacial advance ca. 34-28ka BP correlates with ca. 5℃ winter cooling and ca. 40% less precipitation, which supports temperature driven glaciation whereas a glacial advance ca. 24-22ka BP correlates with ca. 3℃ winter cooling and precipitation similar to present, which supports precipitation forced glaciation. Palaeoenvironmental reconstructions of stadial vegetation from the Westport region indicate lowland Nothofagus fusca-type forest during OIS 4 and a forest-grassland mosaic during OIS 3/2. These records contrast with pollen-based reconstructions of a treeless landscape in Westport during stadials but are consistent with quantitative estimates of stadial cooling. A shift of reproductive strategy in arboreal vegetation may explain the lack of tree pollen in stadial pollen records. This is significant for our understanding of glacial palaeoecology and palaeoclimatology as pollen records may not accurately represent stadial vegetation.
2

A Record of Environmental and Climatic Change from the West Coast, South Island, New Zealand, using Beetle Fossils

Burge, Philip Ian January 2007 (has links)
Fossil beetle based palaeoclimatic and palaeoenvironmental reconstructions are presented from the Westport region, West Coast, South Island, New Zealand for the last glacial cycle. They include the longest continuous fossil beetle record from New Zealand, covering 16,000 years over the OIS 3/OIS 2 transition. Early last glacial (OIS 4) and mid- Holocene (OIS 1) reconstructions are also presented. The assumptions underlying fossil beetle research in New Zealand are tested indicating beetles are suitable proxies for reconstructing palaeotemperature and palaeoprecipitation. This thesis provides the first quantitative estimates of temperature and precipitation from the Westport region for the last glacial. Reconstructed temperatures indicate stadial cooling was seasonal. Maximum cooling was ca. 5℃ in winter and ca. 2-3℃ in summer. Winter cooling is consistent with previous quantitative estimates from New Zealand. Mean annual precipitation decreased a maximum 35-40% during stadials. Temperatures and precipitation varied during OIS 3/2 indicating multiple possible drivers for glaciation. A glacial advance ca. 34-28ka BP correlates with ca. 5℃ winter cooling and ca. 40% less precipitation, which supports temperature driven glaciation whereas a glacial advance ca. 24-22ka BP correlates with ca. 3℃ winter cooling and precipitation similar to present, which supports precipitation forced glaciation. Palaeoenvironmental reconstructions of stadial vegetation from the Westport region indicate lowland Nothofagus fusca-type forest during OIS 4 and a forest-grassland mosaic during OIS 3/2. These records contrast with pollen-based reconstructions of a treeless landscape in Westport during stadials but are consistent with quantitative estimates of stadial cooling. A shift of reproductive strategy in arboreal vegetation may explain the lack of tree pollen in stadial pollen records. This is significant for our understanding of glacial palaeoecology and palaeoclimatology as pollen records may not accurately represent stadial vegetation.
3

Human responses to climate change during the Younger Dryas in Northwest Europe

Andrews, Christopher James January 2018 (has links)
This study discusses the extent to which hunter-gatherer mobility strategies are changed by abrupt climate change events by monitoring changes in lithic assemblage compositions through the Pleistocene/Holocene Transition, from ca. 14,000 cal BP to 10,000 cal BP in northwest Europe, with a focus on the Younger Dryas Stadial event, which occurred around 12,900 cal BP to 11,700 cal BP. A set of predicted archaeological indicators were formed from existing theoretical models, based largely on Binford’s logistical and residential mobility model, with the expectation that a more residential mobility strategy would be used by hunter-gatherer-populations during warmer climatic phases (i.e. the Allerød and Preboreal) and a more logistical mobility strategy would be used during cold climatic phases (i.e. the Younger Dryas). The lithic assemblages from sites across northwest Europe were then compared with these expectations in order to determine if a shift from a more residential strategy to a more logistical strategy can be seen from the lithic record. Additionally, a further comparative dataset was collected from south Europe in order to determine if there were differences in the response to the Younger Dryas at lower latitudes where the impact of this event is assumed to be less severe. The results found that in northwest Europe there is evidence to suggest there was indeed a shift from a more residential strategy during the warm Allerød interstadial to a more logistical strategy during the Younger Dryas Stadial, and the adoption of a more residential strategy with the return of warmer conditions during the Preboreal. However, it appears that the Preboreal Interstadial shows significant differences between the Allerød Interstadial, with the Preboreal sharing more characteristics in common with the Younger Dryas. This has been interpreted as a response to the unstable climatic conditions reported from the environmental evidence in this region during the Preboreal, which may have limited the ability of hunter-gatherer populations to return to similar levels of residential mobility seen during the Allerød. The south Europe dataset provides evidence that the lesser impact of the Younger Dryas at lower latitudes brought about a more muted response by hunter-gatherer populations to this event when compared with the northwest. However, there appears to be a reversal of that seen in the northwest, with more logistically mobile populations during the Allerød and especially the Preboreal, and more residentially mobile populations during the Younger Dryas. This is despite the environmental evidence showing a very similar environmental response to the northwest, with a distinct opening of the landscape during the Younger Dryas. The apparent difference in mobility strategies appear to be more related to the available faunal species within a region and their behaviour within their environment rather than directly to the climate. In the south, species such as red deer and ibex are the main source of faunal subsistence throughout the Pleistocene/Holocene Transition, unchanged by shifts in temperature and environment, but the way in which hunter-gatherers would hunt such species would be expected to change in more wooded environments compared with more open environments. If we compare this with the northwest, there is evidence of a distinct change from hunted prey, such as red deer, during the Allerød and Preboreal, to reindeer and horse during the Younger Dryas (although faunal preservation is poor in this region). With this shift to a more mobile prey species, along with a harsher, more open environment it may be more suitable to practise a more logistical strategy. Additionally, the instability of the Preboreal may have also changed the environment on a smaller scale, which would have required the hunting of warmer climate prey in shifting local environments, much like that of the Younger Dryas in south Europe. This might explain the differences seen between the Allerød and the Preboreal. Overall, there appears to be strong evidence supporting the theory that colder, harsher climates promote a more logistically mobile response from hunter-gatherer populations as seen in the northwest of Europe, and that there was a more muted, different response to the Younger Dryas in the lower latitudes of south Europe. However, it is the opinion here that changes in human mobility are not controlled directly be climatic conditions, rather controlled by the available major prey species and their behaviour in changing environments.
4

Palaeoenvironmental changes in southern Patagonia during the Late-glacial and the Holocene : implications for forest establishment and climate reconstructions

Mansilla, Claudia A. January 2015 (has links)
Three continuous terrestrial high-resolution palaeoenvironmental records for the Late-glacial and the Holocene have been reconstructed for different ecosystems in Fuego-Patagonia on a longitudinal transect at latitude 53°S. The records describe the nature and extent of environmental and climatic changes inferred from palynological evidence supported by lithostratigraphy, tephrochronology and radiocarbon dating. The environmental changes recorded at the three sites displays a significant degree of synchrony in response to similar large-scale climatic changes. Clear stratigraphical evidence alongside the pollen record indicates a shift to warmer interstadial conditions between c. 14,800 Cal yr BP and 14,400 Cal yrs BP. During the period coeval with ACR the vegetation was dominated by cold resistant dry land herbs such as Poaceae, Asteraceae (Suf. Asteroideae) and Acaena, by c. 13,200 Cal yr BP the vegetation changed from the dominance of cold resistant dry land herbs towards more mesic conditions and the expansion of steppe dominated by Poaceae with patches of Nothofagus forest. The establishment of the forest and an eastward shift of the forest-steppe ecotone by c. 12,500 Cal yr BP from which a gradual shift from colder to warmer conditions and the relatively stronger influences of the SSWs is inferred. The sequence of Late-glacial environmental changes places Fuego-Patagonia within the new palaeoecological data provided by this study includes “the earliest” evidence for the establishment of subantarctic Nothofagus forest during the LGIT in Fuego-Patagonia. During the Early-Holocene two major phases of Nothofagus forest expansion were registered between c. 11,700 - 10,500 Cal yr BP and c. 9,500 - 8,200 Cal yr BP. These intervals of expansion of Nothofagus forest are separated by an interval of forest contraction in response to lower effective moisture between c. 10,500 - 9,500 Cal yr BP. An intense arid phase is inferred between c. 8,250 Cal yr BP and 6,800 Cal yr BP and probably leading to an increase in the amount of dry fuel available during the mid-Holocene in Fuego-Patagonia leading to the highest fire activity promoted by very weak SSWs at this time. The later Holocene was characterised by an increase in humidity and an inferred intensification of the SSWs.

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