Influence of permafrost disintegration on wetland carbon fluxes in Abisko, Sweden
(2021) In Student thesis series INES NGEM01 20211Dept of Physical Geography and Ecosystem Science
- Abstract
- The northern permafrost regions are experiencing a rapid warming as surface temperatures are rising, causing a disintegration of permafrost and a deepening of the active layer (AL). This releases previously frozen carbon, making it available for decomposition by microbes. The combination of the high microbial activity and overall wetter soils may cause anoxic conditions and in turn methane (CH4) and carbon dioxide (CO2) release into the atmosphere, further contributing to warming of the climate. The main drivers, and therefore, the magnitude of CO2 and CH4 fluxes may vary spatially (CO2/CH4). Thus, the aim of this study is to investigate the influence of spatial variability of site-specific conditions such as vegetation composition, AL... (More)
- The northern permafrost regions are experiencing a rapid warming as surface temperatures are rising, causing a disintegration of permafrost and a deepening of the active layer (AL). This releases previously frozen carbon, making it available for decomposition by microbes. The combination of the high microbial activity and overall wetter soils may cause anoxic conditions and in turn methane (CH4) and carbon dioxide (CO2) release into the atmosphere, further contributing to warming of the climate. The main drivers, and therefore, the magnitude of CO2 and CH4 fluxes may vary spatially (CO2/CH4). Thus, the aim of this study is to investigate the influence of spatial variability of site-specific conditions such as vegetation composition, AL depth, water table depth (WTD) on the magnitude of carbon fluxes (CO2/CH4) between and within sites. Multiple replicate measurements of CO2 and CH4 concentrations, WTD, AL depth, air temperature (Tair) and soil temperature (Tsoil) were taken from three different locations in Abisko, Sweden. The three study sites had varying stages of permafrost degradation: Storflaket had a relative stable permafrost, Kursflaket is currently undergoing permafrost degradation and Katterjokk has undergone a complete permafrost loss over last few decades. The results showed significant differences in CO2 and CH4 fluxes between and within the sites. The CH4 emissions and CO2 uptake were significantly higher in the site with completely disintegrated permafrost (Katterjokk), compared to the other two sites with permafrost presence. CH4 fluxes were also significantly higher for wet plots, compared to dry plots. The CH4 emissions were shown to be mainly driven by the WTD and AL depth as well as the abundance of aerenchymateous vegetation. No significant relationship between the investigated variables and CO2 fluxes could be found. However, there was a significant difference in ecosystem respiration (Reco) between the wet and dry plots, indicating that there may be a relationship between WTD and CO2. The results demonstrated that even within the Abisko region, there were considerable variations in carbon fluxes as well as drivers of the fluxes between and within the sites. The differences in carbon fluxes and the site-specific conditions are important to take into consideration when extrapolating and generalising for larger areas. Furthermore, a continued disintegration of permafrost and deepening of the AL, may further alter the sub arctic ecosystem of Abisko and thereby enhance the spatial variability, as site-specific conditions continue to change. Moreover, further permafrost disintegration on a global scale may lead to even more CH4 emissions, amplifying the initial warming. (Less)
- Popular Abstract (Swedish)
- Den globala uppvärmningen har stora effekter på det subarktiska ekosystemet i norra Sverige. De ökande temperaturerna i dessa ekosystem har lett till ett tinande av permafrosten i marken. Permafrosten innehåller stora mängder kol och när tjälen i marken försvinner blir detta kol tillgängligt för nedbrytning av mikrober i marken. Denna nedbrytning av kol i kombination med en våtare mark leder till att metan och koldioxid frigörs till atmosfären. Detta leder till en acceleration av den pågående globala uppvärmningen. De faktorer som påverkar mängden metan och koldioxid som frigörs varierar rumsligt och det är därmed stora variationer mellan olika platser inom regionen.
Syftet med denna studie var att undersöka hur mycket den rumsliga... (More) - Den globala uppvärmningen har stora effekter på det subarktiska ekosystemet i norra Sverige. De ökande temperaturerna i dessa ekosystem har lett till ett tinande av permafrosten i marken. Permafrosten innehåller stora mängder kol och när tjälen i marken försvinner blir detta kol tillgängligt för nedbrytning av mikrober i marken. Denna nedbrytning av kol i kombination med en våtare mark leder till att metan och koldioxid frigörs till atmosfären. Detta leder till en acceleration av den pågående globala uppvärmningen. De faktorer som påverkar mängden metan och koldioxid som frigörs varierar rumsligt och det är därmed stora variationer mellan olika platser inom regionen.
Syftet med denna studie var att undersöka hur mycket den rumsliga variationen mellan olika platser i subarktiska Sverige, såsom vegetation, djupet av aktivt lager och vattennivå, påverkar mängden metan och koldioxid som frigörs. För att undersöka detta analyserades data över metan -och koldioxidkoncentrationer, vattennivå, djup av aktivt lager insamlat från tre olika våtmarker i Abisko. Dessa tre våtmarker varierade i mängd underliggande permafrost: Storflaket har en relativt intakt permafrost, Kursflaket har en mindre mängd permafrost kvar och Katterjokk har genomgått en total tining av permafrosten.
Studien visade på att det var stora skillnader i mängden metan - och koldioxidutsläpp, både mellan de tre våtmarkerna och inom varje våtmark. Utsläppen av metan samt upptaget av koldioxid visade sig vara signifikant högre för Katterjokk, som genomgått total permafrosttining, till skillnad från de två andra våtmarkerna som fortfarande har en underliggande permafrost. Utsläppen av metan var också signifikant högre i våta platser jämfört med torra. De faktorer som huvudsakligen drev metanutsläppen var vattennivå, djup av aktivt lager samt mängd metan-transporterande växtlighet.
Resultaten av denna studie visade på att det till och med inom Abisko finns signifikanta skillnader i kolutbytet samt i de faktorer som huvudsakligen driver utbytet av kol. Dessa skillnader är viktiga att ta hänsyn till vid extrapolation och generalisering av resultat för större områden. En ökad temperatur i de norra latituderna kommer att leda till en ökad tining av permafrosten och därmed en fördjupning av det aktiva lagret. Detta kommer i sin tur att förändra de subarktiska ekosystemen ytterligare och därmed förstärka de rumsliga skillnaderna mellan olika områden. Slutligen kommer en fortsatt permafrosttining att leda till ett ökat metan-utsläpp, vilket i sin tur amplifierar den redan ökande temperaturen. (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/9059767
- author
- Esmailzadeh Davani, Aida LU
- supervisor
-
- Lena Ström LU
- Joel White LU
- organization
- course
- NGEM01 20211
- year
- 2021
- type
- H2 - Master's Degree (Two Years)
- subject
- keywords
- Physical Geography, Ecosystem Analysis, Permafrost, CH4 flux, CO2 flux, Abisko, Wetlands
- publication/series
- Student thesis series INES
- report number
- 551
- language
- English
- id
- 9059767
- date added to LUP
- 2021-06-30 10:19:38
- date last changed
- 2021-06-30 10:19:38
@misc{9059767,
abstract = {{The northern permafrost regions are experiencing a rapid warming as surface temperatures are rising, causing a disintegration of permafrost and a deepening of the active layer (AL). This releases previously frozen carbon, making it available for decomposition by microbes. The combination of the high microbial activity and overall wetter soils may cause anoxic conditions and in turn methane (CH4) and carbon dioxide (CO2) release into the atmosphere, further contributing to warming of the climate. The main drivers, and therefore, the magnitude of CO2 and CH4 fluxes may vary spatially (CO2/CH4). Thus, the aim of this study is to investigate the influence of spatial variability of site-specific conditions such as vegetation composition, AL depth, water table depth (WTD) on the magnitude of carbon fluxes (CO2/CH4) between and within sites. Multiple replicate measurements of CO2 and CH4 concentrations, WTD, AL depth, air temperature (Tair) and soil temperature (Tsoil) were taken from three different locations in Abisko, Sweden. The three study sites had varying stages of permafrost degradation: Storflaket had a relative stable permafrost, Kursflaket is currently undergoing permafrost degradation and Katterjokk has undergone a complete permafrost loss over last few decades. The results showed significant differences in CO2 and CH4 fluxes between and within the sites. The CH4 emissions and CO2 uptake were significantly higher in the site with completely disintegrated permafrost (Katterjokk), compared to the other two sites with permafrost presence. CH4 fluxes were also significantly higher for wet plots, compared to dry plots. The CH4 emissions were shown to be mainly driven by the WTD and AL depth as well as the abundance of aerenchymateous vegetation. No significant relationship between the investigated variables and CO2 fluxes could be found. However, there was a significant difference in ecosystem respiration (Reco) between the wet and dry plots, indicating that there may be a relationship between WTD and CO2. The results demonstrated that even within the Abisko region, there were considerable variations in carbon fluxes as well as drivers of the fluxes between and within the sites. The differences in carbon fluxes and the site-specific conditions are important to take into consideration when extrapolating and generalising for larger areas. Furthermore, a continued disintegration of permafrost and deepening of the AL, may further alter the sub arctic ecosystem of Abisko and thereby enhance the spatial variability, as site-specific conditions continue to change. Moreover, further permafrost disintegration on a global scale may lead to even more CH4 emissions, amplifying the initial warming.}},
author = {{Esmailzadeh Davani, Aida}},
language = {{eng}},
note = {{Student Paper}},
series = {{Student thesis series INES}},
title = {{Influence of permafrost disintegration on wetland carbon fluxes in Abisko, Sweden}},
year = {{2021}},
}