Ecology and phytogeography of the mosses of the Bonne Bay region, western Newfoundland

The moss flora of the Bonne Bay region, western Newfoundland, was investigated at 54 sites. These sites represented two physiographic regions, Coastal Plain and Highlands, and four rock types: calcareous, mafic, ultramafic, and acidic. Five lithophysiographic regions combining rock type and physiography were defined. -- The 261 moss species (in 112 genera) known from Bonne Bay comprise about 60% of the known moss flora for the island of Newfoundland. -- Eight species and two varieties of mosses were not previously known from Newfoundland: Arctoa fulvella (a genus new to Newfoundland), Ctenidium molluscum (a genus new to Newfoundland), Desmatodon latifolius var. muticus, D. laureri, Grimmia hartmanii var. anomala, Encalypta longicolla (a species new to eastern North America), Molendoa sentneriana (a genus new to Newfoundland), Orthotrichum obtusifolium, Trichostomum crispulum, and Timmia norvegica var. excurrens. -- The habitats in increasing order of moss diversity were peatlands, coastal exposures, barrens, forests, and freshwater areas. The lithophysiographic regions, in order of increasing moss diversity were, Ultramafic Highlands, Acidic Highlands, Coastal Plain, Mafic Highlands, and Calcareous Highlands. A high similarity among the moss floras of the Calcareous Highlands, Mafic Highlands, and Coastal Plain was attributed to the presence of calciphilic mosses in these regions. A high similarity was also noted between the moss floras of the Mafic and Acidic Highlands. The flora of the Mafic Highlands was considered distinctive and deserving of further study. -- Several species at Bonne Bay are widely disjunct from western North America, and rare in eastern North America: Arctoa fulvella, Campylopus atrovirens, Entodon concinnus, Encalypta longicolla, Grimmia hartmanii var. anomala, Oligotrichum hercynicum, Pseudoleskeella catenulata. These mosses have differing edaphic ecologies and dispersal potentials. Their Newfoundland occurrences are best explained by their having survived glaciation in ice-free areas at, or near, Bonne Bay, a hypothesis supported by recent glacial-geological evidence from the region