Carbon dynamics in forest fire affected permafrost soils
Northern Hemisphere permafrost soils store approximately 50% of the global soil carbon (C), a quarter of which could thaw by the end of the century. Thawing exposes previously frozen soil organic matter (SOM) to decomposition, resulting in release of greenhouse gases (GHG) from the soils. Vast areas...
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Helsingin yliopisto
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ftunivhelsihelda:oai:helda.helsinki.fi:10138/312388 2023-08-20T04:09:08+02:00 Carbon dynamics in forest fire affected permafrost soils Aaltonen, Heidi Paré, David University of Helsinki, Faculty of Agriculture and Forestry Doctoral Programme in Sustainable Use of Renewable Natural Resources Helsingin yliopisto, maatalous-metsätieteellinen tiedekunta Uusiutuvien luonnonvarojen kestävän käytön tohtoriohjelma Helsingfors universitet, agrikultur-forstvetenskapliga fakulteten Doktorandprogrammet i hållbart utnyttjande av förnybara naturresurser Pumpanen, Jukka Berninger, Frank Karhu, Kristiina Köster, Kajar 2020-02-27T10:26:26Z application/pdf http://hdl.handle.net/10138/312388 eng eng Helsingin yliopisto Helsingfors universitet University of Helsinki URN:ISBN:978-951-651-667-0 Unigrafia, Helsinki: 2020, Dissertationes Forestales. 2323-9220 Dissertationes Forestales URN:ISSN:1795-7389 http://hdl.handle.net/10138/312388 URN:ISBN:978-951-651-666-3 Julkaisu on tekijänoikeussäännösten alainen. Teosta voi lukea ja tulostaa henkilökohtaista käyttöä varten. Käyttö kaupallisiin tarkoituksiin on kielletty. This publication is copyrighted. You may download, display and print it for Your own personal use. Commercial use is prohibited. Publikationen är skyddad av upphovsrätten. Den får läsas och skrivas ut för personligt bruk. Användning i kommersiellt syfte är förbjuden. Metsätieteet Text Doctoral dissertation (article-based) Artikkeliväitöskirja Artikelavhandling doctoralThesis 2020 ftunivhelsihelda 2023-07-28T06:04:39Z Northern Hemisphere permafrost soils store approximately 50% of the global soil carbon (C), a quarter of which could thaw by the end of the century. Thawing exposes previously frozen soil organic matter (SOM) to decomposition, resulting in release of greenhouse gases (GHG) from the soils. Vast areas of permafrost soils are covered by boreal forests currently acting as sinks of C. As global warming is strongest at northern latitudes, the occurrence of boreal forest fires may increase. Forest fires further advance permafrost thaw and forest soils may turn from sinks to sources. This thesis examines how forest fires affect the quality of SOM and GHG emissions from permafrost soils in boreal forests by conducting chemical fractionation of SOM and soil incubations, as well as manual chamber measurements of GHGs. Forest fires increased the active layer depth on top of permafrost, altered species composition of vegetation and affected the organic layer depth and the SOM pools. Fires decreased the quality of SOM, observed as reduction in the proportional amount of labile SOM fraction and increased SOM temperature sensitivity, as well as enrichment with heavier isotopes of 13C and 15N. GHG measurements showed that fire initially decreased carbon dioxide flux from the soil and it returned to its pre-fire status approximately 50 years after the fire. The effects of fires on methane and nitrous oxide fluxes were not significant. Forest fires have significant effects on the release of GHGs from permafrost soils. In the future, the fate of permafrost stored SOM is dependent on its degradability, the frequency of fire events and the ability of forests to regenerate, allowing permafrost recovery, in the changing climate. There is a demand for further studies investigating the specifics of different permafrost ecosystems and building a complete picture to estimate total emissions from permafrost regions. Pohjoisen pallonpuoliskon ikiroudan alueet varastoivat noin 50 % maapallon maaperän hiilivaroista. Noin neljänneksen ... Doctoral or Postdoctoral Thesis permafrost Helsingfors Universitet: HELDA – Helsingin yliopiston digitaalinen arkisto |
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Open Polar |
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Helsingfors Universitet: HELDA – Helsingin yliopiston digitaalinen arkisto |
op_collection_id |
ftunivhelsihelda |
language |
English |
topic |
Metsätieteet |
spellingShingle |
Metsätieteet Aaltonen, Heidi Carbon dynamics in forest fire affected permafrost soils |
topic_facet |
Metsätieteet |
description |
Northern Hemisphere permafrost soils store approximately 50% of the global soil carbon (C), a quarter of which could thaw by the end of the century. Thawing exposes previously frozen soil organic matter (SOM) to decomposition, resulting in release of greenhouse gases (GHG) from the soils. Vast areas of permafrost soils are covered by boreal forests currently acting as sinks of C. As global warming is strongest at northern latitudes, the occurrence of boreal forest fires may increase. Forest fires further advance permafrost thaw and forest soils may turn from sinks to sources. This thesis examines how forest fires affect the quality of SOM and GHG emissions from permafrost soils in boreal forests by conducting chemical fractionation of SOM and soil incubations, as well as manual chamber measurements of GHGs. Forest fires increased the active layer depth on top of permafrost, altered species composition of vegetation and affected the organic layer depth and the SOM pools. Fires decreased the quality of SOM, observed as reduction in the proportional amount of labile SOM fraction and increased SOM temperature sensitivity, as well as enrichment with heavier isotopes of 13C and 15N. GHG measurements showed that fire initially decreased carbon dioxide flux from the soil and it returned to its pre-fire status approximately 50 years after the fire. The effects of fires on methane and nitrous oxide fluxes were not significant. Forest fires have significant effects on the release of GHGs from permafrost soils. In the future, the fate of permafrost stored SOM is dependent on its degradability, the frequency of fire events and the ability of forests to regenerate, allowing permafrost recovery, in the changing climate. There is a demand for further studies investigating the specifics of different permafrost ecosystems and building a complete picture to estimate total emissions from permafrost regions. Pohjoisen pallonpuoliskon ikiroudan alueet varastoivat noin 50 % maapallon maaperän hiilivaroista. Noin neljänneksen ... |
author2 |
Paré, David University of Helsinki, Faculty of Agriculture and Forestry Doctoral Programme in Sustainable Use of Renewable Natural Resources Helsingin yliopisto, maatalous-metsätieteellinen tiedekunta Uusiutuvien luonnonvarojen kestävän käytön tohtoriohjelma Helsingfors universitet, agrikultur-forstvetenskapliga fakulteten Doktorandprogrammet i hållbart utnyttjande av förnybara naturresurser Pumpanen, Jukka Berninger, Frank Karhu, Kristiina Köster, Kajar |
format |
Doctoral or Postdoctoral Thesis |
author |
Aaltonen, Heidi |
author_facet |
Aaltonen, Heidi |
author_sort |
Aaltonen, Heidi |
title |
Carbon dynamics in forest fire affected permafrost soils |
title_short |
Carbon dynamics in forest fire affected permafrost soils |
title_full |
Carbon dynamics in forest fire affected permafrost soils |
title_fullStr |
Carbon dynamics in forest fire affected permafrost soils |
title_full_unstemmed |
Carbon dynamics in forest fire affected permafrost soils |
title_sort |
carbon dynamics in forest fire affected permafrost soils |
publisher |
Helsingin yliopisto |
publishDate |
2020 |
url |
http://hdl.handle.net/10138/312388 |
genre |
permafrost |
genre_facet |
permafrost |
op_relation |
URN:ISBN:978-951-651-667-0 Unigrafia, Helsinki: 2020, Dissertationes Forestales. 2323-9220 Dissertationes Forestales URN:ISSN:1795-7389 http://hdl.handle.net/10138/312388 URN:ISBN:978-951-651-666-3 |
op_rights |
Julkaisu on tekijänoikeussäännösten alainen. Teosta voi lukea ja tulostaa henkilökohtaista käyttöä varten. Käyttö kaupallisiin tarkoituksiin on kielletty. This publication is copyrighted. You may download, display and print it for Your own personal use. Commercial use is prohibited. Publikationen är skyddad av upphovsrätten. Den får läsas och skrivas ut för personligt bruk. Användning i kommersiellt syfte är förbjuden. |
_version_ |
1774721876125286400 |