Rewetted industrial cutaway peatlands in western Ireland: a prime location for climate change mitigation?

Rewetting of drained industrial peatlands may reduce greenhouse gas (GHG) emissions and promote recolonisation by peat forming plant species. We investigated carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) dynamics over a three-year period in a rewetted industrial peatland in Ireland. Sample plots were established in bare peat, Juncus effusus-Sphagnum cuspidatum, Sphagnum cuspidatum and Eriophorum angustifolium dominated microsites. The relationships between fluxes and environmental variables were examined and regression models were used to provide an estimate of the annual GHG balance for each microsite. All the vegetated microsites were carbon sinks for the duration of the study. Highest uptake occurred in the Eriophorum microsite (146–583 g C m-2 yr-1), followed by Juncus-Sphagnum (35–204 g C m-2 yr-1) and Sphagnum (5–140 g C m-2 yr-1). The bare peat microsite was a source of 37–82 g C m-2 yr-1. No N2O fluxes were detected. Strong inter-annual variation was observed in all microsites, driven by variation in precipitation and subsequent changes in the position of the water table. In terms of Global Warming Potential (GWP), the microsites had either a cooling effect (Eriophorum), a close to neutral effect (Juncus-Sphagnum, Sphagnum) or a warming effect (bare peat) on the climate.