Relationship of Bryophyte Occurrence to Rock Type in Upstate New York and Coastal Maine

Abstract Bryophytes are often noted for their growth on specific rock types and their value as indicator species. However, some evidence suggests that restriction of a species to specific rock types may be less rigid and could vary under different environmental conditions. We assessed richness and distribution patterns of bryophytes at 22 rock outcrop locations in upstate New York (NY) and coastal Maine (ACAD). At each location, detailed surveys were done in five replicate 5-m by 2-m plots on vertical rock faces. We report on the 194 bryophyte species found in these surveys and present detailed analyses for the 137 species that occurred at two or more of the 22 locations. In general, liverworts were less likely to be dominant within a plot than mosses. Within-site dominance and frequency of liverworts were less well correlated to larger-scale frequency (number of locations and regions of occurrence). In NY, although there was no significant difference in bryophyte richness by rock type, rare species were ...