Plant Communities in the Gradient from Raised Bog to Fen in a Near-Intact Lagg Zone in Carrownagappul Bog, Ireland

Despite the importance of lagg zones in the function and restoration of raised bog systems, there have been limited studies on their vegetation communities and environmental characteristics. Given their importance and lack of study, the vegetation in the near-intact lagg zone in the south-south-west of Carrownagappul Bog in Co. Galway was sampled along four transects in July 2020. Cluster analysis separated the vegetation, encompassing 97 species, into 5 vegetation types. There were affinities between these vegetation types and a range of Irish Vegetation Classification (IVC) bog, heath, grassland and fen communities, as well as two Habitats Directive Annex I habitat types, transition mires and alkaline fen. In addition, a population of the Annex II listed Marsh Fritillary (Euphydryas aurinia (Rottemburg, 1775)) was recorded from the area. In general, the vegetation communities reflected a gradient of increasing alkalinity, moisture and nutrient status from ombrotrophic raised bog to minerotrophic fen. The diversity of the vegetation over a small area and its near-natural conditions underscore the conservation significance of the lagg zone, and these findings accentuate the hydrological perspective that restoration of the lagg should, where possible, be a key element in raised bog restoration. The current lack of a characterisation of the lagg types found in Ireland is a barrier to developing a sound restoration and conservation management strategy.