Grassland contribution to carbon sequestration in the LULUCF inventory for Northern Ireland

The early recognition that there has been a considerable increase in greenhouse gas (GHG) emissions emitted from agriculture practices, has led to improve grassland management to store carbon (C) and offset anthropogenic emissions of the farming sector. The United Kingdom (UK) Climate Change Act 2008, which extends to Northern Ireland (NI), requires an 80 % reduction in emissions across all sectors by 2050. Grassland in NI, represents 79 % of the agricultural land area and agriculture is the largest source sector of GHG emissions. Under this commitment and other international agreements, it is required to provide information and land use change data for reporting GHG emissions and removals from Land Use, Land Use Change and Forestry (LULUCF). The UK has chosen to use a wide definition of grassland in its LULUCF inventory which includes improved and semi natural grassland and other habitats that may not be grassy vegetation. Further, there are other sources of activity data that are currently excluded from the inventory that may also benefit NI’s inventory such as hedgerows, sequestration value of scrub, woodland strips and agroforestry.
Hence, to ensure that any benefit to NI’s inventory is not overlooked, this study analysed and evaluated activity data and emission factors that are currently applied in the NI LULUCF inventory and to derive more accurate estimates relevant to NI’s conditions.
The study found important gaps in activity data for NI such as C stock changes in grassland living biomass, dead organic matter and soil C changes in mineral or organic grassland soils. These gaps are particularly important in long-term grassland where equilibrium in C accumulation is assumed be reached in 20 years (IPCC, 2006). Other activities not included in the LULUCF inventory were hedge management, C dynamics in soils below hedges and application of manure to grassland which is a potential mitigation strategy. Therefore in order to establish a clear link between land use management practices and the reporting mechanism used to monitor emission changes in NI, the current gaps and assumptions in relation to the LULUCF inventory need to be addressed. This will help to ensure that C sequestration activities in the country are better represented in the inventory.