Community assembly in epiphytic bryophyte communities along the vertical gradient in a Colombian tropical rainforest

Abstract

Abstract. Bryophytes are the main components of epiphyte diversity in tropical rain forests and documenting their biodiversity patterns is still a fundamental goal in bryophyte ecology. Thus, we aimed to analyze the composition (generalists, shade-loving and sun-tolerant) and total richness of epiphytic bryophytes along a vertical gradient in the Buenavista Forest Reserve in Villavicencio, Orinoquia, Colombia, where biodiversity patterns of epiphytic bryophytes are still unknown. Microplots were collected in seven trees, in six tree zones: base, lower trunk, upper trunk, inner canopy, middle canopy, and outer canopy. Variation in species composition was tested through PERMANOVA and we used one-way ANOVA to seek for differences in species richness among tree zones. Indicator species analysis was used to investigate whether there were preferences among species for any of the tree zones. We found 22 liverworts and 12 mosses. Species richness was significantly different among the tree zones with tree bases hosting the highest richness and the upper trunk, inner canopy and outer canopy the lowest. The highest number of indicator species was found in the middle canopy. The base was dominated by shade-loving while the outer canopy was distinguished by sun-tolerant species. Thus, epiphytic bryophyte communities are structured according to the vertical zonation on the trees, which seem to form specific microclimates that directly influence the distribution patterns of the species, particularly the shade-loving and sun-tolerant. Our findings provide insights to the understanding of assembly mechanisms of epiphytic bryophyte diversity, particularly in heavily impacted areas by anthropogenic activities, such as the secondary forests of the Colombian Orinoquia.