The impacts of High Arctic permafrost disturbances on vegetation and carbon flux dynamics
Changing climate and disturbance regimes can have widespread ecosystem impacts, especially in the Arctic. Vegetation recovery and carbon flux dynamics were examined to determine the impacts of thermokarst disturbance on patterns and processes in High Arctic tundra ecosystems. Ecosystem responses to...
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ftunivbritcolcir:oai:circle.library.ubc.ca:2429/59332 2023-05-15T14:58:02+02:00 The impacts of High Arctic permafrost disturbances on vegetation and carbon flux dynamics Cassidy, Alison Elizabeth 2016 http://hdl.handle.net/2429/59332 eng eng University of British Columbia Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/ CC-BY-NC-ND Text Thesis/Dissertation 2016 ftunivbritcolcir 2019-10-15T18:21:26Z Changing climate and disturbance regimes can have widespread ecosystem impacts, especially in the Arctic. Vegetation recovery and carbon flux dynamics were examined to determine the impacts of thermokarst disturbance on patterns and processes in High Arctic tundra ecosystems. Ecosystem responses to two forms of permafrost disturbance, active layer detachment slides and retrogressive thaw slumps, were studied on the Fosheim Peninsula, Ellesmere Island, Canada during the 2012, 2013, and 2014 growing seasons. The impacts of disturbance on vegetation and recovery were determined by sampling active retrogressive thaw slumps and recovered active layer detachment slides that were investigated nearly 20 years ago. Comparison of historic and modern data indicates distinct vegetation communities exist in differently aged disturbances with unique vascular plant species defining various zones and ages of disturbance. Differences were also found in site characteristics (including soil moisture, temperature, active layer depth, and soil nutrient concentrations) indicating the impacts of permafrost disturbance on the landscape. In addition, four active layer detachment slides measured in 1994 had transitioned to active retrogressive thaw slumps, which may be a response to the progressively warming climate. Carbon dioxide fluxes between the surface and the atmosphere were measured using a static chamber system and the eddy covariance technique at three sites on the Fosheim Peninsula. Over the studied growing seasons, disturbed landscapes sequestered significantly less carbon than their surrounding undisturbed tundra. In some sites, this resulted in the shift of the system from a net sink of CO₂ to a net source. A dual eddy covariance sampling approach was found to be preferable over a single tower setup with separation of fluxes based on wind partitioning as disturbed and undisturbed fluxes were simultaneously measured throughout the growing season using this method. Overall, active layer detachments and retrogressive thaw slumps alter vegetation and carbon flux dynamics, and these changes may persist over many years. With predicted increases in the frequency and magnitude of these permafrost disturbances, impacts on tundra ecosystems will be evident at the landscape scale. Arts, Faculty of Geography, Department of Graduate Thesis Arctic Ellesmere Island Fosheim Peninsula permafrost Thermokarst Tundra University of British Columbia: cIRcle - UBC's Information Repository Arctic Ellesmere Island Canada Fosheim Peninsula ENVELOPE(-83.749,-83.749,79.669,79.669) |
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Open Polar |
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University of British Columbia: cIRcle - UBC's Information Repository |
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ftunivbritcolcir |
language |
English |
description |
Changing climate and disturbance regimes can have widespread ecosystem impacts, especially in the Arctic. Vegetation recovery and carbon flux dynamics were examined to determine the impacts of thermokarst disturbance on patterns and processes in High Arctic tundra ecosystems. Ecosystem responses to two forms of permafrost disturbance, active layer detachment slides and retrogressive thaw slumps, were studied on the Fosheim Peninsula, Ellesmere Island, Canada during the 2012, 2013, and 2014 growing seasons. The impacts of disturbance on vegetation and recovery were determined by sampling active retrogressive thaw slumps and recovered active layer detachment slides that were investigated nearly 20 years ago. Comparison of historic and modern data indicates distinct vegetation communities exist in differently aged disturbances with unique vascular plant species defining various zones and ages of disturbance. Differences were also found in site characteristics (including soil moisture, temperature, active layer depth, and soil nutrient concentrations) indicating the impacts of permafrost disturbance on the landscape. In addition, four active layer detachment slides measured in 1994 had transitioned to active retrogressive thaw slumps, which may be a response to the progressively warming climate. Carbon dioxide fluxes between the surface and the atmosphere were measured using a static chamber system and the eddy covariance technique at three sites on the Fosheim Peninsula. Over the studied growing seasons, disturbed landscapes sequestered significantly less carbon than their surrounding undisturbed tundra. In some sites, this resulted in the shift of the system from a net sink of CO₂ to a net source. A dual eddy covariance sampling approach was found to be preferable over a single tower setup with separation of fluxes based on wind partitioning as disturbed and undisturbed fluxes were simultaneously measured throughout the growing season using this method. Overall, active layer detachments and retrogressive thaw slumps alter vegetation and carbon flux dynamics, and these changes may persist over many years. With predicted increases in the frequency and magnitude of these permafrost disturbances, impacts on tundra ecosystems will be evident at the landscape scale. Arts, Faculty of Geography, Department of Graduate |
format |
Thesis |
author |
Cassidy, Alison Elizabeth |
spellingShingle |
Cassidy, Alison Elizabeth The impacts of High Arctic permafrost disturbances on vegetation and carbon flux dynamics |
author_facet |
Cassidy, Alison Elizabeth |
author_sort |
Cassidy, Alison Elizabeth |
title |
The impacts of High Arctic permafrost disturbances on vegetation and carbon flux dynamics |
title_short |
The impacts of High Arctic permafrost disturbances on vegetation and carbon flux dynamics |
title_full |
The impacts of High Arctic permafrost disturbances on vegetation and carbon flux dynamics |
title_fullStr |
The impacts of High Arctic permafrost disturbances on vegetation and carbon flux dynamics |
title_full_unstemmed |
The impacts of High Arctic permafrost disturbances on vegetation and carbon flux dynamics |
title_sort |
impacts of high arctic permafrost disturbances on vegetation and carbon flux dynamics |
publisher |
University of British Columbia |
publishDate |
2016 |
url |
http://hdl.handle.net/2429/59332 |
long_lat |
ENVELOPE(-83.749,-83.749,79.669,79.669) |
geographic |
Arctic Ellesmere Island Canada Fosheim Peninsula |
geographic_facet |
Arctic Ellesmere Island Canada Fosheim Peninsula |
genre |
Arctic Ellesmere Island Fosheim Peninsula permafrost Thermokarst Tundra |
genre_facet |
Arctic Ellesmere Island Fosheim Peninsula permafrost Thermokarst Tundra |
op_rights |
Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/ |
op_rightsnorm |
CC-BY-NC-ND |
_version_ |
1766330122285088768 |