Vertical distribution and diversity of epiphytic bryophytes in the Colombian Amazon

Introduction. The purpose of this study was to analyse the variation in the vertical and spatial distribution of epiphytic bryophytes across four forests in the north-western Amazon. We sampled along the entire vertical gradient from tree base to upper canopy in order to answer these questions: Is there vertical zonation? Is there a relationship between composition species and geographical distance? Methods. The vertical gradient was studied in 64 phorophytes, and each phorophyte was divided into six height zones. We used Detrended Corresponded Analysis for plot ordination and Permutation Multivariate Analysis of Variance to analyse variation in species composition. The relationship between species composition and geographic distance was evaluated using a Mantel Test. We used Indicator species analysis to determine the preference of the species for each of the six height zones, and an ANOVA analysis to evaluate the significance of species richness per zone. Key results. There was a gradual differentiation of the bryophyte communities across the tree height zones. We identified 63 indicator species; the tree base had the highest number of indicator species, followed by the outer canopy. Conclusions. The strong influence of height zones on species assemblages revealed the importance of the environmental differences across the vertical gradient within a single tree. Epiphytic bryophyte communities are mainly structured according to the height zone of trees. The presence of a high percentage of indicator species across the Colombian Amazon is evidence to further support a high specificity of species for a particular microhabitat within the forest.