Restoration of lowland raised bogs damaged by peat extraction - with particular emphasis on Sphagnum regeneration.

1. Revegetation trends in abandoned peat workings indicate that peat cuttings are \ngenerally too dry for spontaneous re-establishment of raised bog vegetation. The latter \nwas restricted to small flooded peat pits which had recolonised 'hydroserally' to \nsupport floating rafts of bog vegetation. \n2. The water storage capacity of cut-over bog surfaces is low compared with \nundisturbed bog and blocking drains in a peat field at Thorne Moors, S. Yorks, was \ninsufficient to prevent water-table instability. Experiments suggest this may severely \ninhibit Sphagnum growth. Lagoons may increase water storage on a bog surface and \nfacilitate development of raised bog vegetation as floating rafts. This 'hydroseral' \napproach may be necessary to restore raised bog vegetation to some areas. \n3. Hydrochemical conditions of cut-over sites may differ significantly from \nundisturbed bogs with implications for Sphagnum growth. Water samples from a peat \nfield at Thorne Moors were comparatively acidic and contained comparatively high \nconcentrations of most major ions (particularly NH4 and SO4), except phosphorus. \nModerate nutrient enrichment is unlikely to adversely affect Sphagnum and additions \nof phosphorus to flooded peat pits significantly increased its growth. In solution \nculture, low pH (3.0-3.5) was sub-optimal for Sphagnum growth, but the use of \nCaCO3 to reduce acidity in the field had a toxic effect. \n4. Sphagnum recolonisation may be limited by availability of propagules in cut-over \nareas. Experiments indicate that deliberate re-introduction encourages Sphagnum raft \ndevelopment, which is pioneered by aquatic species that regenerate more prolifically \nfrom fragments than intact gametophytes. Sphagnum rafts are encouraged in shallow \nwater (< 5 0cm) and pools of small area. Numerous management options exist \nphysically and chemically assisting raft development.