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Tree line shifts, changing vegetation assemblages and permafrost dynamics on Galdhøpiggen (Jotunheimen, Norway) over the past ~4400 years
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John Hiemstra ,
Sietse Los
The Holocene, Volume: 32, Issue: 4, Pages: 308 - 320
Swansea University Authors:
Helen Hallang, Cynthia Froyd , John Hiemstra , Sietse Los
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DOI (Published version): 10.1177/09596836211066591
Abstract
An environmental reconstruction based on palynological evidence preserved in peat was carried out to examine late-Holocene alpine tree line dynamics in the context of past climatic changes on Galdhøpiggen (Jotunheimen, southern Norway). We analysed a peat core taken from a mire at the present-day tr...
| Published in: | The Holocene |
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| ISSN: | 0959-6836 1477-0911 |
| Published: |
SAGE Publications
2022
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| Online Access: |
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| URI: | https://cronfa.swan.ac.uk/Record/cronfa59122 |
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| Abstract: |
An environmental reconstruction based on palynological evidence preserved in peat was carried out to examine late-Holocene alpine tree line dynamics in the context of past climatic changes on Galdhøpiggen (Jotunheimen, southern Norway). We analysed a peat core taken from a mire at the present-day tree line (1000 m a.s.l.), c. 450 m downslope from the lower limit of sporadic permafrost. We adopted a combination of commonly used indicators of species’ local presence to reconstruct past vegetation assemblages, such as the relative pollen abundance (%), pollen accumulation rate (PAR), and presence of indicator species. Additionally, fossil pollen from the peat sequence was compared to modern pollen from a surface moss polster to establish a modern analogue. The results were compared with studies covering the late-Holocene climatic changes in the area. The reconstruction demonstrates that a pine-dominated woodland reached above the present-day tree line at c. 4300 cal. yr BP, suggesting a warmer climate suitable for Scots pine ( Pinus sylvestris) growth at this altitude. Scots pine retreated to lower altitudes between c. 3400 and 1700 cal. yr BP, accompanied by the descent of the low-alpine shrub-dominated belt, in response to cooling climatic conditions. The colder period covered c. 1700–170 cal. yr BP, and an open downy birch ( Betula pubescens) woodland became widespread at 1000 m a.s.l., whilst pine remained sparse at this altitude. From c. 170 cal. yr BP onwards, warming allowed pine to re-establish its local presence alongside downy birch at 1000 m a.s.l. |
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| Keywords: |
alpine vegetation, palynology, permafrost, reconstruction, treelines |
| College: |
Faculty of Science and Engineering |
| Funders: |
Quaternary Research Association Grant: New Research Workers’ Award 2019 Identifier: FundRef 10.13039/100012089 |
| Issue: |
4 |
| Start Page: |
308 |
| End Page: |
320 |