Diversity of Epiphytic Bryophytes on Three Host Tree Species, Thermal Meadow, Hotsprings Island, Queen Charlotte Islands, Canada

Abstract

Three tree species (Picea sitchensis, Thuja plicata, and Tsuga heterophylla) near hot springs were examined for epiphytic bryophyte abundance and diversity on Queen Charlotte Islands. Cover was recorded at four heights up to 5 m, and on branches on the north and south sides of each tree. Eleven species of mosses and 25 species of hepatics were found. Cover was greater for mosses than hepatics but mosses had lower beta diversity. Bryophyte species composition differed by tree species, with species richness increasing in the order Tsuga, Picea, and Thuja. The similarity of mosses, and the dissimilarity of hepatics, on the north and south sides of trees, suggest relatively subtle diferences in moisture conditions. Ordinations indicate that epiphytic bryophytes followed a tree-position gradient that is closely related to a vertical gradient. Several species typical of log and forest floor habitats were found as branch epiphytes. Our findings support the previous observation that the vertical gradient in species composition parallels macroclimatic and successional gradients.