One of the main aims of this study was to ‘assess the impact of drainage and restoration on GHG emissions’ and to then ‘provide guidelines for the restoration of other degraded raised bogs’.
The study found that ‘even relatively intact bogs are sources of CO₂ to the atmosphere because of a limited distribution of Sphagnum species. The water table dynamic is the critical driver of GHG emissions and further confirms that peatland carbon and water cycling are strongly coupled’.
The research found that ‘Natura 2000 sites in Ireland emit approximately 80% more CO₂ than they sequester. Raised bogs, and peatlands in Ireland generally, are therefore considered significant sources of CO₂ and must be accounted for in GHG land use inventory reporting. The value of bog restoration is thus not as much about creating a carbon sink as it is about preserving the peat carbon store and reducing emissions’.
Engineering solutions required to restore the hydrological balance of degraded raised bogs, and their carbon sink function, were then evaluated in the research. It was found that ‘restoration must reinstate a functioning acrotelm (layer of peat containing living plants) and this study finds that the optimum topographic condition for this is having a slope gradient below 0.6%’. ‘To maximise regeneration potential, restoration works must restore the surface water slopes (the hydraulic gradient) that ensure maximum water table depths of 0.2 m beneath the ground surface’. The principles presented in this research relate to both degraded raised bogs that are partly intact and cutover bog that are dominated by bare peat (i.e. no vegetation cover/exposed peat surface).
The research findings and associated publication therefore provide principles that can be used as guidelines for assessing the restoration potential and complexity of restoration design for raised bog ecosystems in Ireland.