Epiphytic bryophytes growing on Laurus azorica (Seub.) Franco in three laurel forest areas in Tenerife (Canary Islands)

We examined bryophyte species growing on Laurus azorica, in three localities of the laurel forest in Tenerife (Canary Islands), in order to determine differences in species composition, richness and cover, that depend on variations in mist frequency and density. Among the 35 bryophyte species found (26 liverworts and nine mosses), 16 occurred in all three locations while nine species occurred in only one location. Detrended correspondence analysis and canonical correspondence analysis revealed that the epiphyte-phorophyte relationship varied in terms of cover, richness and bryophyte composition, depending on the humidity conditions (related to mist frequency and plot height) and tree age. In spite of differences in the dominant species found at each locality, the community types have many species in common and may be seen as a natural unit of the communities involved. Variation in the dominant species at each locality is mainly related to a trade off between humidity conditions and tree diameter, and the speed of the successional processes. Plot aspect was the only variable among those considered with no significant influence, which might be related to the closed canopy conditions. Variation in cover, richness and bryophyte composition related to plot height and tree diameter increased in the drier location. Cover was positively related to species richness in all analyses. This is related to low diversity during initial colonization and the fact that the highest biomass species, related to later successional stages, also occur on younger trees, especially in the more humid areas. (C) 2004 Elsevier SAS. All rights reserved.