Evaluating blanket mire vegetation recovery following hydrological restoration, with specific focus on the influence of Molinia caerulea

Abstract

This thesis evaluates the ecological processes involved in passive blanket peatland vegetation restoration following hydrological rewetting and evaluates the role of Molinia caerulea tussock development as a barrier to blanket mire vegetation establishment. Using data collected from restoration pools and terrestrial peat surfaces across blanket bog habitats on Dartmoor National Park, vegetation responses to rewetting over timescales of up to 10 years were evaluated. Observations were made on the restorative processes of terrestrialisation in pools and paludification of the terrestrial peat surface, and on the role of M. caerulea tussocks in shaping microclimates and vegetation assemblages. Results show that aquatic Sphagnum species had rapid colonisation potential where propagules occur in flow pathways, with 76% of pools containing Sphagnum within 18 months. Sphagnum colonisation and abundance are controlled by pool depth and rainfall consistency, with reduced cover observed as a result of low spring and summer precipitation. Paludification occurs rapidly within three years close to pool edges, but wider establishment is slower. Lawn Sphagnum and associated mire species re-colonise into the dominant dry peat vegetation simultaneously at distances up to 10m from pool edges where the water table is maintained at the near surface within 7-10 years, but plant competition from dominant Molinia caerulea tussocks remains a measurable constraint. M. caerulea tussocks create significant warming and desiccating effects, with larger tussocks and higher densities amplifying temperature and moisture differences. These microclimatic changes further promote M. caerulea preservation and expansion at the expense of Sphagnum and other mire vegetation, particularly in areas of shallow peat where water tables fluctuate. Anthropogenic induced climate change is likely to worsen these effects by further increasing suitability for M. caerulea dominance in the context of upland peatland systems. Interactions between mire vegetation and both hydrology and M. caerulea competition must not be overlooked if we are to effectively manage blanket peatland habitats in a sustainable way. Long-term successful peatland restoration will depend not only on maintaining near-surface water tables but also ensuring connectivity between restoration pools and managing M. caerulea dominance to ensure favourable conditions for aquatic and terrestrial Sphagna.

Date of Award	2026
Original language	English
Awarding Institution	University of Plymouth
Supervisor	Paul Lunt (Director of Studies (First Supervisor)) & Scott Davidson (Other Supervisor)