Mid- to Late Holocene environmental dynamics on the Yukon Coastal Plain and Herschel Island (Canada) – evidence from polygonal peatlands and lake sediment
The North American Arctic witnessed high-amplitude climatic change during the Early Holocene that resulted in regional-scale environmental change. These changes are well documented in the literature. The environmental impacts of moderate climatic oscillations during the Mid- to Late Holocene are les...
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| Format: | Thesis |
| Language: | unknown |
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2017
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| Online Access: | https://epic.awi.de/id/eprint/44730/ https://epic.awi.de/id/eprint/44730/1/Wolter_PhDthesis.pdf https://hdl.handle.net/10013/epic.51372 https://hdl.handle.net/10013/epic.51372.d001 |
| Summary: | The North American Arctic witnessed high-amplitude climatic change during the Early Holocene that resulted in regional-scale environmental change. These changes are well documented in the literature. The environmental impacts of moderate climatic oscillations during the Mid- to Late Holocene are less well understood, especially on the Yukon Coastal Plain, which is geographically and topographically isolated from the rest of the western Canadian Arctic. The region is currently experiencing increased thaw of ice-rich permafrost, alterations in landscape water balance, and shrub expansion. These processes are connected to severe transformations in a landscape that is overwhelmingly composed of periglacial landforms. Especially the widespread thaw lakes and ice-wedge polygons are known to be vulnerable to climatic and geomorphic change because of their direct dependence on permafrost conditions, and hence on air temperatures. Tundra vegetation dynamics are linked to permafrost conditions and geomorphology, yet the interplay between vegetation, permafrost, geomorphology and climate is not well articulated in Low Arctic tundra. Finally, the temporal and spatial scales at which climatic change and geomorphic processes may affect periglacial landforms on the one hand and tundra vegetation on the other hand are not clearly constrained. Yet, these scale-dependent relationships are crucial components of the adaptation and resilience potential of high-latitude environments. This thesis identified long-term as well as short-term trends in the development of thaw lakes, ice-wedge polygons and tundra vegetation during the Mid- to Late Holocene. This was done by studying modern, sub-decadal, and centennial- to millennial-scale records from ice-wedge polygons and lake sediment in different landscape units on the Yukon Coastal Plain. Additionally, drivers of change to these systems and possible causes of environmental stability were assessed. To address and constrain the wide range of spatial and temporal dimensions involved in ... |
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