ERTDI Report 53 - Ward et al.
Summary: Synthesis Report for ERTDI-funded project: 2000-LS-5.1.2b-M1
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Peatlands are thought to contribute significantly to the greenhouse gas (GHG) fluxes in Ireland. The accumulation of carbon in stable peatlands can be regarded as sequestration to a store, while emission of carbon due to decomposition of long-term carbon stores would be regarded as a source. The balance between carbon storage and emission is dependent on peat type and change in use through time. To understand the role of peatland in the inventory of Ireland’s GHG emissions it is necessary to quantify the national peatland resource and its associated fluxes.
The aims of project 2000-LS-5.1.2b-M1 were to quantify and classify the national peatland resource, and to assess the GHG fluxes associated with each peat class. These data would then permit estimation of the contribution of peatlands to national GHG fluxes. These aims have been addressed by:
The estimate of the peat resource in the Republic of Ireland, derived from PEATGIS, suggests that peatlands cover ca 0.95 Mha or ca 14% of the total land area, and that around 74% of peatlands are disturbed in some way. These area estimates are similar to those of CORINE (Coordination of Information on the Environment), while the disturbance data are somewhat lower than the Irish Peatlands Conservation Council (IPCC) estimates of 82% for blanket bog and 92% for raised bog. The PEATGIS tool was designed to be used with new digital data sets as they become available.
The preliminary results derived from the PORTACH II model are subject to some uncertainty because the modelled system has not captured all the important processes that occur. While some detail in the model may not be exact, the general values derived indicate that, on balance, it is quite possible that the level of disturbance of Irish peatlands might be causing a release of long-term stored carbon. For example, sequestration rates of raised bogs were estimated to range from around –16 g C m
As there is uncertainty associated with the GIS/modelling approach, the method was used to evaluate whether, on balance, it was more likely that Irish peatlands are acting as carbon sinks or sources. Best- and worst-case scenarios were evaluated to estimate the range of results possible: best case +0.6 Mt C/year, worst case –0.1 Mt C/year. Land-use scenarios based on IPCC- and PEATGIS-derived disturbance rates were used to estimate that the carbon balance is probably close to neutral: IPCC –0.02 Mt/year, PEATGIS +0.04 Mt/year, which are small deviations from neutral compared to the total possible range. The results showed that peatlands and their status significantly affect carbon fluxes and underline how important this issue is for Ireland considering that 74% of Irish peat bogs are probably disturbed.
The project has facilitated the development of two new quantitative methodologies that can predict the total peatland area as well as estimate carbon fluxes from these peatlands. Future work will develop these ideas to permit estimation of total peatland carbon storage, and improved formulation of the peat carbon flux model.
Final Report available from the STRIVE/ERTDI Section
2 /year for disturbed situations (i.e. loss of long-term stored carbon) to around +60 g C m 2 /year for undisturbed situations (i.e. sequestration of carbon). A revision of modelled processes is ongoing.