Renou-Wilson F., Wilson D., and C. Müller
Proceedings of the 14th International Peat Congress
climate-change, grassland, methane, organic-soil, rewetting
Renou-Wilson et al 2012: Methane Emissions From Organic Soils Under Grassland: Impacts of Rewetting
Theme X. Peatland carbon budgets and greenhouse gas (GHG) fluxes
Grassland is a major land use category in the Republic of Ireland and a significant source of greenhouse (GHG) emissions. In reporting carbon (C) emissions from grassland on organic soils, the Republic of Ireland currently uses the Tier 1 default value of 0.25 t/C/ha. This value is at variance with Emissions Factors (EFs) used by countries in similar climatic zone and suggests that Ireland may have underestimated C emissions from this land use category.
The CALISTO project (www.ucd.ie/calisto) aims to provide a comprehensive overview of C dynamics in organic soils under grassland by quantifying the gaseous fluxes of carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O) and fluvial C losses (DOC, POC, pCO2, DIC) at four peatland sites under grassland and, therefore, move to Tier 2 level reporting. At the same time, we are investigating the impacts of re-establishing a high water table in order to reduce CO2 losses. However, an increase in CH4 emissions due to rewetting is also expected therefore compromising the full atmospheric impact of such mitigation measures. Preliminary results of CH4 fluxes will be presented and discussed in terms of an optimal water table to minimise CH4 emissions. This work is relevant in the context of the “2013 Supplement to 2006 IPCC Guidelines for National Greenhouse Gas Inventories: Wetlands” whereby tiered methodological approaches are being discussed for the rewetting and restoration of peatlands.