Remediation and restoration of ocean exposed cliff-top, in the context of Dounreay (Scotland) nuclear power plant decommissioning

  • David Braidwood

    Student thesis: Doctoral ThesisDoctor of Philosophy (awarded by OU/Aberdeen)


    Restoration ecology continues to become ever more relevant as legislation demands we prevent biodiversity losses. Post-industrial restoration sites pose a number of additional challenges, including balancing ecological need with logistical and financial constraints. In the North of Scotland, one such site is the Dounreay Nuclear Power Plant, now undergoing decommissioning. The intention is to restore cliff-top habitat with native vegetation, blending in with its surroundings and necessitating minimal maintenance. The overall objective of this PhD research was to help develop a plan for the restoration of the site. A key challenge in this particular case was the residual low level radioactivity at depth in some areas, and a restoration layer is required to prevent contamination of bioreceptors at the surface, however, topsoil availability is limited.
    The cliff top site, and exposure to salt spray driven by strong winds, meant the identification of suitable vegetation communities for different areas could be crucial to its success. Vegetation and soil surveys across nine reference sites along the North coast of Scotland identified five non-peat vegetation communities suitable for Dounreay’s restoration.
    To test what combination of substrates and topsoils would support better germination a controlled experiment in a growth chamber, followed by an in situ vegetation trial plot experiment, was carried out. Vegetation germinated without topsoil on fine grade crushed rocks, though cover, richness, diversity and biomass were all lower in treatments without topsoil than where topsoil was present, mostly due to lower soil moisture and nutrient levels. The level of cover continued to increase throughout the three years of the trial plots when topsoil was absent, and in time levels for these variables may become equal. Invertebrate richness and diversity within the trial plots were compared with neighbouring reference sites. Our results suggest that a functional invertebrate community was rapidly restored to the tested treatments.
    The exclosure of part of the site for up to 300 years means that the site will be left to develop for a long time without further human intervention: therefore, the effects of climate change should to be taken in to account in the selection of species to include in the restoration. A search through herbarium specimens revealed no loss of those species from the north of Scotland in the past ca. 150 years, despite changes in regional temperatures. Projected changes in temperature during the coming 50 years show a dramatic shift in space likely to be occupied by species found there now.
    Date of Award4 May 2018
    Original languageEnglish
    Awarding Institution
    • University of Edinburgh
    SponsorsDounrey Site Restoration Ltd (DSRL)
    SupervisorRoxane Andersen (Supervisor), Mark Taggart (Supervisor) & Melanie Smith (Supervisor)

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