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This study assessed the short-term impacts of ditch blocking on water table depth and vegetation community structure in a historically drained blanket bog. A chronosequence approach was used to compare vegetation near ditches blocked 5 years, 4 years and 1 year prior to the study with vegetation near unblocked ditches. Plots adjacent to and 3 m away from 70 ditches within an area of blanket bog were assessed for floristic composition, aeration depth using steel bars, and topography using LiDAR data. No changes in aeration depth or vegetation parameters were detected as a function of ditch-blocking, time since blocking, or distance from the ditch, with the exception of non-Sphagnum bryophytes which had lower cover in quadrats adjacent to ditches that had been blocked for 5 years. Analysis of LiDAR data and the observed proximity of the water table to the peat surface led us to conclude that the subdued ecosystem responses to ditch-blocking were the result of historical peat subsidence within a 4-5 m zone either side of each ditch, which had effectively lowered the peat surface to the new, ditch-influenced water table. We estimate that this process led to the loss of around 500,000 m peat within the 38 km study area following drainage, due to a combination of oxidation and compaction. Assuming that 50% of the volume loss was due to oxidation, this amounts to a carbon loss of 11,000 Mg C over this area, i.e. 3 Mg C ha. The apparent 'self-rewetting' of blanket bogs in the decades following drainage has implications for their restoration as it suggests that there may not be large quantities of dry peat left to rewet, and that there is a risk of inundation (potentially leading to high methane emissions) along subsided ditch lines. Many peatland processes are likely to be maintained in drained blanket bog, including support of typical peatland vegetation, but infilling of lost peat and recovery of original C stocks are likely to take longer than is generally anticipated.

Demographic techniques have been employed to study populations of the rare orchid @ark loeselii var. ovata across a range of dune slack habitats at a South Wales site. The study has shown that very large numbers of shoots (>300) may occur within a single 1 x 1 m quadrat and that the vegetative production of side shoots is common. Regular population surveys over time have shown that individuals represented by a single shoot can live for 8 years. Subsequent analyses of the floristic composition of the study quadrats has revealed the presence of subtle variations in species composition and vegetation structure in relation to age and hydrology, although all of the plots still fall within the SD14 Salk repens-Campylium stellatum dune slack community defined by the British National Vegetation Classification. When attributes of population flux are analysed in relation to floristic composition, one significant trend to emerge is that the appearance of new genets is most prevalent in successionally young slacks. As the natural formation of new slacks by sand blow is now a rare event in the South Wales dune field, the management of Lipark loeselii var. ovata is currently aimed at attempting to ensure the persistence of suitable communities through biomass reduction techniques.

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