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Impacts of restoration and climate variability on peatland GHG fluxes Nyberg, Marion

Abstract

Peatland disturbance through drainage threatens to liberate large amounts of C stocks by increasing emissions of carbon dioxide (CO₂) from the soil. Restoration through re-wetting, on the other hand, could play an important role in climate change mitigation or adaptation by reducing CO₂ emissions and increasing the ability of peatland to sequester atmospheric CO₂. However, this can come at the cost of increased CH₄ emissions, an extremely potent greenhouse gas, and therefore rewetting can lead to a biogeochemical compromise between CO₂ uptake and storage, and CH₄ release. Currently, there is large uncertainty surrounding the extent of this compromise in ecosystems at different stages of recovery and with differing environmental conditions, making it difficult to predict how well these ecosystems are able to regain their function as CO₂ sinks following restoration. To assess the effect of re-wetting, I analysed eddy-covariance flux measurements alongside environmental variables from sites that have undergone different restoration techniques and consequently have different environmental conditions, mainly water table height (WTH). By the end of the one-year study period, the site with a higher water table, i.e., the wetter site, was a CO₂ sink, and the drier site was a CO₂ source. CH₄ emissions were higher at the wetter site annually and in the growing season, and whilst both sites had a positive radiative balance when calculated using sustained global warming potentials, the wetter site had a lower radiative balance on both a 20- and 100- year time horizon than the drier site, implying the importance of CO₂ sink status for climate benefits. These results emphasize the role that WTH and soil temperature have on promoting or inhibiting CO₂ and CH₄ emissions, and therefore can be used to inform management decisions and predict future trends in peatland ecosystems undergoing restoration.

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Attribution-NonCommercial-NoDerivatives 4.0 International

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