Bog in a Box: Is Long Term Peat Storage for Future Restoration Viable?
Covering less than 3% of the Earth’s landmass but containing around a third of all organic soil carbon, peatlands are both one of the world rarest and most important habitats in terms of biodiversity and climate regulation. However, this does not make them immune to damage by development pressures and the human need for resources. In 2010, construction started on an onshore natural gas terminal in the Shetland islands, an archipelago densely covered in blanket bog which form the most northerly reach of the UK. In an attempt to mitigate for the damage, it was decided that all 672,000 m3 of peat had to excavated would be stored in purpose built wet storage for use in future reinstatement, a novel idea not attempted elsewhere. Through the use of a carbon assessment and investigations into the belowground activity, peat condition, pore water chemistry, comparison to a local restored and reference site and revegetation strategies, this thesis begins to address the question of the viability of long-term peat storage for future restoration. Almost a decade on after construction, belowground function of the peat within the store is different to that of a nearby reference blanket bog largely due to lower peat quality and to the artificially high and stable water table in the peat store. The changes in the physical condition and chemistry of the peat (compacted, denser peat enriched in nutrient and cation) are likely to present barriers to the rehabilitation goals of the decommissioned site when peat is reinstated, and prevent the recovery of a hydrological regime and vegetation communities associated with a functional blanket bog . In addition, climatic factors such as wind erosion will present a further barrier to the rehabilitation of the decommissioned site, as supported by results from a study of a local restored site and from an outdoor mesocosm study sited at the Shetland Gas Plant. In that mesoscom study where several revegetation strategies were examined, a combination of a modified moss layer transfer technique and hydroseeding proved to be the most successful in establishing a diverse ground cover, protecting and stabilising peat and accumulating biomass within the study period, outperforming either of the other technique in isolation. . Overall, whilst long-term peat storage may have benefits in terms of protecting more peat carbon than it emitted (not including the as yet to be incurred decommissioning emissions), it cannot be recommended for future peatland developments. The evidence from this thesis implies that the changes made to the peat condition in combination with other barriers such as climate change mean that blanket bog habitat cannot be restored to the site in any meaningful time period, meaning that it has been permanently lost in a time of biodiversity and climate crisis. However, in this case the storing of the peat (as opposed to disposal) does provide options for the decommissioned SGP site to rehabilitate some function to the landscape, provided rehabilitation goals and end points are adjusted to achievable ones.
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