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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

High Forest or Wood Pasture: A model of Large Herbivores' impact on European Lowland Vegetation

Yao, Xuefei January 2010 (has links)
<p>Natural forest dynamics is a foundational topic of forest science. A new Wood Pasture hypothesis considering large herbivore as driving force in forest ecosystem is now challenging the traditional High Forest hypothesis, in which vegetation is regarded as main driving force. In this study, a model-based approach is applied to investigate differences between these two hypotheses and the determine factors in the system. A theoretical landscape of 1 km²formed by 100*100 cells is set up with 100 vegetation patches and free moving herbivores on. Our null hypothesis that herbivores make no difference in vegetation dynamics especially at canopy level is rejected. It is found that synchronization of herbivore behaviors is the most influencing factor of how a landscape might be shaped. It is also found that landscape could be a mosaic of both high forest and wood pasture depends on large herbivore’s herd size.</p>
2

High Forest or Wood Pasture: A model of Large Herbivores' impact on European Lowland Vegetation

Yao, Xuefei January 2010 (has links)
Natural forest dynamics is a foundational topic of forest science. A new Wood Pasture hypothesis considering large herbivore as driving force in forest ecosystem is now challenging the traditional High Forest hypothesis, in which vegetation is regarded as main driving force. In this study, a model-based approach is applied to investigate differences between these two hypotheses and the determine factors in the system. A theoretical landscape of 1 km²formed by 100*100 cells is set up with 100 vegetation patches and free moving herbivores on. Our null hypothesis that herbivores make no difference in vegetation dynamics especially at canopy level is rejected. It is found that synchronization of herbivore behaviors is the most influencing factor of how a landscape might be shaped. It is also found that landscape could be a mosaic of both high forest and wood pasture depends on large herbivore’s herd size.
3

20,000 14C Years of Climate and Environmental Change in Europe : A Coleopteran-based Reconstruction with an Anthropocenic Focus

Enayat, Misha January 2015 (has links)
This thesis builds on the work of previous coleopteran-based climatic reconstructions to recreate the environment and climate of the last 20,000 14C years of northwest Europe using the data and methods available within the Bugs Coleopteran Ecology Package, and aims to assess the ability of the BugsCEP results to provide information regarding events and anthropogenic changes on environment during the Anthropocene. Samples and data from 134 sites across northwest Europe and the British Isles were included in this study. The Mutual Climatic Range method and the BugStats module based on habitat code classifications were used to create the climatic and environmental reconstructions respectively, the results of which are provided in eight isotherm maps for 14.5-9 14C years BP and 2 EcoFigure graphs for 20,000 14C to present. While the results of some isotherm maps align with the changes described in previous studies, other climate trends are muted within these results. Likewise, some previously recognized environmental shifts in Europe are visible, whereas other major events are not distinguishable within the environmental record. An assessment of the environmental reconstruction results finds that though there is not sufficient material to support any proposed Anthropocene start dates, effects of anthropogenic influence upon the environment may be visible starting within the last 2,000 14C years; the results also show some support for the Vera Hypothesis.

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