Respiration of aged soil carbon during fall in permafrost peatlands enhanced by active layer deepening following wildfire but limited following thermokarst
Permafrost peatlands store globally significant amounts of soil organic carbon (SOC) that may be vulnerable to climate change. Permafrost thaw exposes deeper, older SOC to microbial activity, but SOC vulnerability to mineralization and release as carbon dioxide is likely influenced by the soil envir...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
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IOP Publishing
2018-01-01
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| Series: | Environmental Research Letters |
| Subjects: | |
| Online Access: | https://doi.org/10.1088/1748-9326/aad5f0 |
| _version_ | 1797748203832999936 |
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| author | Cristian Estop-Aragonés Claudia I Czimczik Liam Heffernan Carolyn Gibson Jennifer C Walker Xiaomei Xu David Olefeldt |
| author_facet | Cristian Estop-Aragonés Claudia I Czimczik Liam Heffernan Carolyn Gibson Jennifer C Walker Xiaomei Xu David Olefeldt |
| author_sort | Cristian Estop-Aragonés |
| collection | DOAJ |
| description | Permafrost peatlands store globally significant amounts of soil organic carbon (SOC) that may be vulnerable to climate change. Permafrost thaw exposes deeper, older SOC to microbial activity, but SOC vulnerability to mineralization and release as carbon dioxide is likely influenced by the soil environmental conditions that follow thaw. Permafrost thaw in peat plateaus, the dominant type of permafrost peatlands in North America, occurs both through deepening of the active layer and through thermokarst. Active layer deepening exposes aged SOC to predominately oxic conditions, while thermokarst is associated with complete permafrost thaw which leads to ground subsidence, inundation and soil anoxic conditions. Thermokarst often follows active layer deepening, and wildfire is an important trigger of this sequence. We compared the mineralization rate of aged SOC at an intact peat plateau (∼70 cm oxic active layer), a burned peat plateau (∼120 cm oxic active layer), and a thermokarst bog (∼550 cm anoxic peat profile) by measuring respired ^14 C–CO _2 . Measurements were done in fall when surface temperatures were near-freezing while deeper soil temperatures were still close to their seasonal maxima. Aged SOC (1600 yrs BP) contributed 22.1 ± 11.3% and 3.5 ± 3.1% to soil respiration in the burned and intact peat plateau, respectively, indicating a fivefold higher rate of aged SOC mineralization in the burned than intact peat plateau (0.15 ± 0.07 versus 0.03 ± 0.03 g CO _2 –C m ^−2 d ^−1 ). None or minimal contribution of aged SOC to soil respiration was detected within the thermokarst bog, regardless of whether thaw had occurred decades or centuries ago. While more data from other sites and seasons are required, our study provides strong evidence of substantially increased respiration of aged SOC from burned peat plateaus with deepened active layer, while also suggesting inhibition of aged SOC respiration under anoxic conditions in thermokarst bogs. |
| first_indexed | 2024-03-12T16:01:33Z |
| format | Article |
| id | doaj.art-55c86612053845e39db0de3b98a6d41f |
| institution | Directory Open Access Journal |
| issn | 1748-9326 |
| language | English |
| last_indexed | 2024-03-12T16:01:33Z |
| publishDate | 2018-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | Environmental Research Letters |
| spelling | doaj.art-55c86612053845e39db0de3b98a6d41f2023-08-09T14:35:50ZengIOP PublishingEnvironmental Research Letters1748-93262018-01-0113808500210.1088/1748-9326/aad5f0Respiration of aged soil carbon during fall in permafrost peatlands enhanced by active layer deepening following wildfire but limited following thermokarstCristian Estop-Aragonés0https://orcid.org/0000-0003-3231-9967Claudia I Czimczik1https://orcid.org/0000-0002-8251-6603Liam Heffernan2Carolyn Gibson3Jennifer C Walker4Xiaomei Xu5David Olefeldt6Department of Renewable Resources, University of Alberta , Edmonton, Alberta T6G 2H1, CanadaDepartment of Earth System Science, University of California , Irvine, CA 92697-3100, United States of AmericaDepartment of Renewable Resources, University of Alberta , Edmonton, Alberta T6G 2H1, CanadaDepartment of Renewable Resources, University of Alberta , Edmonton, Alberta T6G 2H1, CanadaDepartment of Earth System Science, University of California , Irvine, CA 92697-3100, United States of AmericaDepartment of Earth System Science, University of California , Irvine, CA 92697-3100, United States of AmericaDepartment of Renewable Resources, University of Alberta , Edmonton, Alberta T6G 2H1, CanadaPermafrost peatlands store globally significant amounts of soil organic carbon (SOC) that may be vulnerable to climate change. Permafrost thaw exposes deeper, older SOC to microbial activity, but SOC vulnerability to mineralization and release as carbon dioxide is likely influenced by the soil environmental conditions that follow thaw. Permafrost thaw in peat plateaus, the dominant type of permafrost peatlands in North America, occurs both through deepening of the active layer and through thermokarst. Active layer deepening exposes aged SOC to predominately oxic conditions, while thermokarst is associated with complete permafrost thaw which leads to ground subsidence, inundation and soil anoxic conditions. Thermokarst often follows active layer deepening, and wildfire is an important trigger of this sequence. We compared the mineralization rate of aged SOC at an intact peat plateau (∼70 cm oxic active layer), a burned peat plateau (∼120 cm oxic active layer), and a thermokarst bog (∼550 cm anoxic peat profile) by measuring respired ^14 C–CO _2 . Measurements were done in fall when surface temperatures were near-freezing while deeper soil temperatures were still close to their seasonal maxima. Aged SOC (1600 yrs BP) contributed 22.1 ± 11.3% and 3.5 ± 3.1% to soil respiration in the burned and intact peat plateau, respectively, indicating a fivefold higher rate of aged SOC mineralization in the burned than intact peat plateau (0.15 ± 0.07 versus 0.03 ± 0.03 g CO _2 –C m ^−2 d ^−1 ). None or minimal contribution of aged SOC to soil respiration was detected within the thermokarst bog, regardless of whether thaw had occurred decades or centuries ago. While more data from other sites and seasons are required, our study provides strong evidence of substantially increased respiration of aged SOC from burned peat plateaus with deepened active layer, while also suggesting inhibition of aged SOC respiration under anoxic conditions in thermokarst bogs.https://doi.org/10.1088/1748-9326/aad5f0permafrost thawwildfirepeatlandsactive layer deepeningthermokarstsoil organic carbon |
| spellingShingle | Cristian Estop-Aragonés Claudia I Czimczik Liam Heffernan Carolyn Gibson Jennifer C Walker Xiaomei Xu David Olefeldt Respiration of aged soil carbon during fall in permafrost peatlands enhanced by active layer deepening following wildfire but limited following thermokarst Environmental Research Letters permafrost thaw wildfire peatlands active layer deepening thermokarst soil organic carbon |
| title | Respiration of aged soil carbon during fall in permafrost peatlands enhanced by active layer deepening following wildfire but limited following thermokarst |
| title_full | Respiration of aged soil carbon during fall in permafrost peatlands enhanced by active layer deepening following wildfire but limited following thermokarst |
| title_fullStr | Respiration of aged soil carbon during fall in permafrost peatlands enhanced by active layer deepening following wildfire but limited following thermokarst |
| title_full_unstemmed | Respiration of aged soil carbon during fall in permafrost peatlands enhanced by active layer deepening following wildfire but limited following thermokarst |
| title_short | Respiration of aged soil carbon during fall in permafrost peatlands enhanced by active layer deepening following wildfire but limited following thermokarst |
| title_sort | respiration of aged soil carbon during fall in permafrost peatlands enhanced by active layer deepening following wildfire but limited following thermokarst |
| topic | permafrost thaw wildfire peatlands active layer deepening thermokarst soil organic carbon |
| url | https://doi.org/10.1088/1748-9326/aad5f0 |
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