Epsilon Archive for Student Projects

Abstract

Northern peatland ecosystems cover approximately 3 % of the land area and store almost one-third of the soil carbon, thus are peatlands valuable ecosystem to understand in the context of climate change and climate mitigation. Understanding how peatlands respond to key environmental drivers and how CO₂ and CH₄ fluxes vary across climate zones is crucial for predicting future carbon dynamics. Using eddy covariance measurements, this study investigated carbon and greenhouse gas fluxes at three contrasting peatlands along a latitudinal gradient in Sweden, from hemi-boreal to subarctic conditions, with the aim of characterising climatic trends, assessing flux responses to key environmental drivers, and quantifying seasonal and annual CO₂ and CH₄ budgets. Environmental drivers, including air temperature (Ta), vapour pressure deficit (VPD), incoming shortwave radiation (SWIN) and water table level (WTL), were assessed. Climatic trends reveal that temperature will increase the most in northern regions, as will precipitation. CO2 and CH4 fluxes were strongly regulated by environmental conditions, with ecosystem respiration (RECO) and CH4 emissions showing the highest temperature sensitivity at the central site, while photosynthetic capacity was highest in the south and light-use efficiency was strongest in the north. Gross primary production (GPP) increased with both VPD and Ta but levelled off at higher values. Despite all three sites functioned as net CO₂ sinks in most years, CH₄ emissions resulted in a positive greenhouse gas balance (GWP100) across all sites, indicating a net warming effect over a 100-year horizon. These results highlight that both the magnitude and environmental sensitivity of greenhouse gas (GHG) fluxes differ among peatlands along a latitudinal gradient, emphasising the need for site-specific assessments when evaluating peatland climate feedback.