The known moss flora of Terra Nova National Park, eastern Newfoundland,
comp~ises 210 species. Eighty-two percent of the moss species occurring in Terra
Nova are widespread or widespread-sporadic in Newfoundland. Other
Newfoundland distributional elements present in the Terra Nova moss flora are
the northwestern, southern, southeastern, and disjunct elements, but four of the
mosses occurring in Terra Nova appear to belong to a previously unrecognized
northeastern element of the Newfoundland flora.
The majority (70.9%) of Terra Nova's mosses are of boreal affinity and are
widely distributed in the North American coniferous forest belt. An additional
10.5 percent of the Terra Nova mosses are cosmopolitan while 9.5 percent are
temperate and 4.8 percent are arctic-montane species. The remaining 4.3 percent
of the mosses are of montane affinity, and disjunct between eastern and western
North America. In Terra Nova, temperate species at their northern limit are
concentrated in balsam fir stands, while arctic-montane species are restricted to
exposed cliffs, scree slopes, and coastal exposures. Montane species are largely
confined to exposed or freshwater habitats. Inability to tolerate high summer
temperatures limits the distributions of both arctic-montane and montane species.
In Terra Nova, species of differing phytogeographic affinities co-occur on
cliffs and scree slopes. The microhabitat relationships of five selected species from
such habitats were evaluated by Discriminant Functions Analysis and Multiple
Regression Analysis. The five mosses have distinct and different microhabitats on
cliffs and scree slopes in Terra Nova, and abundance of all but one is associated with variation in at least one microhabitat variable. Micro-distribution of
Grimmia torquata, an arctic-montane species at its southern limit, appears to be
deterJ]lined by sensitivity to high summer temperatures. Both southern mosses at
their northern limit (Aulacomnium androgynum, Isothecium myosuroides)
appear to be limited by water availability and, possibly, by low winter
temperatures. The two species whose distributions extend both north and south or
the study area (Encalypta procera, Eurhynchium pulchellum) show no clear
relationship with microclimate.
Dispersal factors have played a significant role in the development of the
Terra Nova moss flora. Compared to the most likely colonizing source (i .e. the
rest of the island of Newfoundland), species with small diaspores have colonized
the study area to a proportionately much greater extent than have species with
large diaspores. Hierarchical log-linear analysis indicates that this is so for all
affinity groups present in Terra Nova. The apparent dispersal effects emphasize
the comparatively recent glaciation of the area, and may also have been enhanced
by anthropogenic influences. The restriction of some species to specific habitats,
or to narrowly defined microhabitats, appears to strengthen selection for easily
dispersed taxa