Spatiotemporal dynamics of carbon cycling and thermokarst in response to climate and fire-regime changes in the Arctic tundra biome
Amplified climate change and fire regime shifts in the northern high latitudes are posing growing threat to key properties and functions of tundra ecosystems, including soil carbon stock, permafrost stability and vegetation types. However, it remains poorly understood how tundra ecosystems will feed...
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ftunivillidea:oai:www.ideals.illinois.edu:2142/108664 2024-10-13T14:05:17+00:00 Spatiotemporal dynamics of carbon cycling and thermokarst in response to climate and fire-regime changes in the Arctic tundra biome Chen, Yaping Hu, Feng Sheng Fraterrigo, Jennifer M Lara, Mark J Jain, Atul 2020-08 application/pdf http://hdl.handle.net/2142/108664 en eng http://hdl.handle.net/2142/108664 Copyright 2020 Yaping Chen Arctic tundra ecosystem fire disturbance climate change permafrost carbon cycling thermokarst shrub expansion text Thesis 2020 ftunivillidea 2024-10-01T12:57:45Z Amplified climate change and fire regime shifts in the northern high latitudes are posing growing threat to key properties and functions of tundra ecosystems, including soil carbon stock, permafrost stability and vegetation types. However, it remains poorly understood how tundra ecosystems will feedback to the combined forces of changing climate and fire disturbance. In this study, I integrated paleoecology, numerical modeling and remote sensing observation to address (1) the resilience and sensitivity of tundra carbon stocks to shifting fire regimes, (2) the consequences of climate change and fire disturbance on thermokarst disturbance (e.g. collapse of ground surface after permafrost thaw), and (3) the patterns of shrub expansion in heterogenous tundra landscape in response to accelerated warming and fire disturbance. My results indicate that fire disturbance has threshold effects on tundra carbon stocks. Variation in fire return intervals from 5000 to 900 years causes minimal carbon stock loss (<5%). However, increasing fire frequency beyond every 800 years is projected to trigger sustained mobilization of ancient soil organic matter that leads to irreversible carbon stock loss from permafrost. Multi-decade remote sensing observations revealed that tundra fires resulted in pervasive thermokarst formation, and that this impact lasted more than four decades. Nevertheless, substantial spatial heterogeneity exists regarding thermokarst formation and the greatest amount of thermokarst appears in severely burned tundra ecosystems in ice-rich areas. Although fire disturbance is a strong force exacerbating permafrost degradation, widespread warming surpasses sporadic burning as the primary driver responsible for ~90% of thermokarst growth in northern Alaskan tundra over the past ~70 yrs. Permafrost thawing strongly influences shrub cover dynamics in tundra ecosystems, but the net outcome is largely contingent on topographical positions. In poorly drained tundra lowlands, thermokarst-induced water impounding ... Thesis Arctic Climate change Ice permafrost Thermokarst Tundra University of Illinois at Urbana-Champaign: IDEALS (Illinois Digital Environment for Access to Learning and Scholarship) Arctic |
institution |
Open Polar |
collection |
University of Illinois at Urbana-Champaign: IDEALS (Illinois Digital Environment for Access to Learning and Scholarship) |
op_collection_id |
ftunivillidea |
language |
English |
topic |
Arctic tundra ecosystem fire disturbance climate change permafrost carbon cycling thermokarst shrub expansion |
spellingShingle |
Arctic tundra ecosystem fire disturbance climate change permafrost carbon cycling thermokarst shrub expansion Chen, Yaping Spatiotemporal dynamics of carbon cycling and thermokarst in response to climate and fire-regime changes in the Arctic tundra biome |
topic_facet |
Arctic tundra ecosystem fire disturbance climate change permafrost carbon cycling thermokarst shrub expansion |
description |
Amplified climate change and fire regime shifts in the northern high latitudes are posing growing threat to key properties and functions of tundra ecosystems, including soil carbon stock, permafrost stability and vegetation types. However, it remains poorly understood how tundra ecosystems will feedback to the combined forces of changing climate and fire disturbance. In this study, I integrated paleoecology, numerical modeling and remote sensing observation to address (1) the resilience and sensitivity of tundra carbon stocks to shifting fire regimes, (2) the consequences of climate change and fire disturbance on thermokarst disturbance (e.g. collapse of ground surface after permafrost thaw), and (3) the patterns of shrub expansion in heterogenous tundra landscape in response to accelerated warming and fire disturbance. My results indicate that fire disturbance has threshold effects on tundra carbon stocks. Variation in fire return intervals from 5000 to 900 years causes minimal carbon stock loss (<5%). However, increasing fire frequency beyond every 800 years is projected to trigger sustained mobilization of ancient soil organic matter that leads to irreversible carbon stock loss from permafrost. Multi-decade remote sensing observations revealed that tundra fires resulted in pervasive thermokarst formation, and that this impact lasted more than four decades. Nevertheless, substantial spatial heterogeneity exists regarding thermokarst formation and the greatest amount of thermokarst appears in severely burned tundra ecosystems in ice-rich areas. Although fire disturbance is a strong force exacerbating permafrost degradation, widespread warming surpasses sporadic burning as the primary driver responsible for ~90% of thermokarst growth in northern Alaskan tundra over the past ~70 yrs. Permafrost thawing strongly influences shrub cover dynamics in tundra ecosystems, but the net outcome is largely contingent on topographical positions. In poorly drained tundra lowlands, thermokarst-induced water impounding ... |
author2 |
Hu, Feng Sheng Fraterrigo, Jennifer M Lara, Mark J Jain, Atul |
format |
Thesis |
author |
Chen, Yaping |
author_facet |
Chen, Yaping |
author_sort |
Chen, Yaping |
title |
Spatiotemporal dynamics of carbon cycling and thermokarst in response to climate and fire-regime changes in the Arctic tundra biome |
title_short |
Spatiotemporal dynamics of carbon cycling and thermokarst in response to climate and fire-regime changes in the Arctic tundra biome |
title_full |
Spatiotemporal dynamics of carbon cycling and thermokarst in response to climate and fire-regime changes in the Arctic tundra biome |
title_fullStr |
Spatiotemporal dynamics of carbon cycling and thermokarst in response to climate and fire-regime changes in the Arctic tundra biome |
title_full_unstemmed |
Spatiotemporal dynamics of carbon cycling and thermokarst in response to climate and fire-regime changes in the Arctic tundra biome |
title_sort |
spatiotemporal dynamics of carbon cycling and thermokarst in response to climate and fire-regime changes in the arctic tundra biome |
publishDate |
2020 |
url |
http://hdl.handle.net/2142/108664 |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Arctic Climate change Ice permafrost Thermokarst Tundra |
genre_facet |
Arctic Climate change Ice permafrost Thermokarst Tundra |
op_relation |
http://hdl.handle.net/2142/108664 |
op_rights |
Copyright 2020 Yaping Chen |
_version_ |
1812811355093204992 |