Greenhouse Gas Flux Patterns from Abandoned Peat Extraction Sites and Recently Restored Peatlands in Estonia

Intact peatlands sequester and store substantial amounts of carbon over the long-term period. However, if these peatlands are drained for various purposes, e.g., peat mining, agricultural use, or forestry, they become significant greenhouse gas sources. In Estonia, there are still large areas where peat extraction stopped decades ago, and no significant restoration activities have been implemented. All these areas are significant greenhouse gas sources. Restoring such areas into wetlands may turn these large CO₂ sources into sinks and mitigate climate change. However, there remains considerable uncertainty as to whether these sites will become net carbon sinks and to what degree restoration and management methods affect CO₂ sequestration efficiency and potential increase in CH₄ emissions. Our current study focuses on carbon fluxes from abandoned peat extraction sites and recently restored peatlands in Estonia. Both sites (Lavassaare and Ess-soo bogs) were used for peat mining and were abandoned more than 30 years ago. Ess-soo bog was successfully rewetted in 2021. However, the Lavassaare site is currently abandoned, with restoration works scheduled to begin in late 2024. Here, we use eddy covariance towers to synthesize the continuous CO₂ and CH₄ flux data from both study sites using open path analyzers (LI-7500 and LI-7700, LICOR Biosciences). The eddy towers were installed at the Lavassaare site in September 2022 and Ess-soo in June 2023. Our results showed that Lavassaare abandoned peat extraction area is still a significant carbon source with annual emissions of 125 g CO₂-C m^-2 y ^-1 and 1.5 g CH₄-C m^-2 y ^-1. Preliminary results from Ess-soo restored bog indicate reduced CO₂ loss and increased CH₄ flux. However, the vegetation is still under development. This study shows that abandoned peat extraction sites are continuous carbon sources to the atmosphere, while simply rewetting these sites could remarkably reduce CO₂ loss.