Evaluation of climate change mitigation strategies for Irish forests using the CBM-CFS3 model

Background The Irish Forestry greenhouse gas (GHG) profile is undergoing a transition from a net sink to net emission because of persisting emissions from organic soils, an increase in harvest and shifts in the age class structure of plantation forests. The forestry GHG trend diverges from the required National and European Union (EU) policy pathway for land use land use change and forestry (LULUCF) and agriculture aimed at halving emissions by 2030 and achieving carbon neutrality by 2050. A recalibrated version of the Carbon Budget Model of the Canadian Forest Service (CBM-CFS3) was used to assess the impact of identified national forest policy measures on the forest GHG profile over the short to long term. Results An analysis of projected scenarios revealed that, under current silvicultural practices and afforestation policies (with existing measures—WEMs), Irish forests will continue to be a long-term emission beyond 2070 unless harvest rates and management practices are adjusted to negate the adverse impact of emissions from organic soils and fluctuations in historic afforestation rates. The implementation of additional measures (WAM) suggests that the forest sink can be sustained if harvest rates exceed 75% of the net annual increment (NAI), additional afforestation targets are met and if plantation rotation age is increased. Although additional afforestation and a reduction in deforestation is required to meet long-term carbon-neutral goals, the implementation of these policies has a minimal short-term impact on the 2030 targets set out under the National Climate Change Plan (CAP 24) and the revised EU LULUCF regulation (841/2023). Conclusion The results show that the extension of rotation age and associated reductions in harvest levels will have the greatest short-term impact on climate change mitigation, which can be delivered at a negative marginal abatement cost. However, even if WAM forest measures are implemented, Ireland is unlikely to meet the National and EU LULUCF targets by 2030 because of a decreasing forest sink.