The Dynamics of Sphagnum in Forest and Peatland Communities in Southeastern Labrador, Canada

Long fire rotation, high levels of precipitation, and acidic nature of the bedrock are factors contributing to the dominance of Sphagnum in many upland and peatland communities in southeastern Labrador. Vegetation development induced by local or regional environmental change frequently involves replacement of species assemblages of various bryophytes and lichens by species assemblages dominated by Sphagnum. In upland forests the successional sequence following fire often culminates in a carpet of Sphagnum girgensohnii overgrowing feather mosses. Similarly, following a change in the water table, Sphagnum lindbergii encroaches as a broad carpet over Cladopodiella fluitans and Gymnocolea inflata on recently exposed mud bottoms in bog hollows. On bog hummocks, following fire or changes in the moisture regime, Sphagnum fuscum overtops Cladonia lichens to form a pronounced recurrence horizon.Key words: Sphagnum, vegetation development, fire, Labrador, paludification, succession, bryophytes