Vegetation succession post rehabilitation of an industrial cutaway Atlantic blanket bog

Abstract

Bord na Móna harvested peat at Bellacorick (Oweninny works) in County Mayo between 1961 and 2003. Milled peat was harvested from an area of over 6,500 ha of former Atlantic blanket bog and associated habitat types. The peat was supplied to the adjoining peat burning power station at Bellacorick. Peat production ceased in 2003 and a large scale site specific rehabilitation plan was designed and implemented. The main aims of the rehabilitation were to ensure environmental stabilisation of the former industrial peat production area (cutaway bog) and mitigation of silt run-off. A baseline ecology survey of the site was completed in 2001. The rehabilitation work on the cutaway bog was carried out in phases between 2001 and 2005 and comprised an extensive and comprehensive programme of drain blocking, wetland creation, terracing to mitigate erosion on slopes and silt pond decommissioning. The site was re-surveyed in 2011 and the main changes in vegetation cover and composition between 2001 and 2011 were recorded. The study found that sections of the site where the rehabilitation work allowed for water retention were quick to re-vegetate. Sections of the site where water retention was not possible (slopes and gravel ridges) have been slower to re-vegetate. Vegetation cover has increased across the site, bare peat occupied 53.3% of the site in 2001, and by 2011 this had reduced to 11.7%. Quadrats were set up across the site in order to analysis the vegetation and monitor future vegetation changes. Data Analysis of the vegetation data found that seven vegetation communities were present across the former peat production areas. Six of the vegetation communities belonged in the poor fen category with one belonging to a dry heath vegetation type. The six poor fen vegetation types were found to be at various stages of development ranging from dry, Juncus effusus dominated to Sphagnum-rich/abundant. A sequence of development within the poor fen communities has been identified where Juncus effusus is the first plant to colonise the bare peat and in doing so allows other plant species to become established. With time these areas become more diverse, culminating in Sphagnum-iv rich/abundant poor fen in areas where the hydrology is suitable. Following on from the rehabilitation work, pioneer poor fen vegetation has increased by 44.4% and Sphagnum-rich, poor fen (>50% Sphagnum) cover has increased by almost 7% across the site. The establishment of habitats with a high cover of Sphagnum indicates that there is significant potential for sections of the site to revert to peat-forming systems.