Browsing by Subject "Ikiroutasuot"

Permafrost peatlands have a significant role in the global carbon cycle, as they store ca. 185 Pg of carbon. Because of the slow decomposition of organic matter, they have sequestered carbon dioxide from the atmosphere and cooled the climate for thousands of years. However, in anaerobic decomposition also methane – a strong greenhouse gas – is produced. Climate change results in changes in permafrost peatland habitats; distribution and proportional share and these changes also affect the CO2 and CH4 fluxes. In this master’s thesis I compare the net ecosystem exchange and pore water methane concentrations in different microhabitats in the Stordalen palsa mire in Abisko, Sweden. In addition, I review the reported climate change-driven habitat changes in the area and its effects on the CO2 and CH4 fluxes. My results suggest that Sphagnum sp. and Sphagnum fuscum -microhabitats were net sinks of CO2 whereas lichen-, shrub- and Eriophorum-microhabitats were net sources. These results were best explained by the proportional coverage of green vegetation, which was highest in both Sphagnum-microhabitats. No discernible differences were found between pore water methane concentrations in different habitats. Permafrost thawing has increased the occurrence of wet habitats in Stordalen. These habitat changes have increased carbon sequestration in the area but at the same time methane emissions have also increased. Because of this, the radiative forcing of the peatland has changed from negative to positive and the on-going habitat changes will likely continue in future. On a longer timespan though, the radiative forcing will likely switch back to negative as carbon sequestration increases and the effects of the methane emissions decrease.