Effects of environmental heterogeneity on species diversity and composition of terrestrial bryophyte assemblages in tropical montane forests of southern Ecuador

Abstract

Background: Most studies on tropical bryophytes deal with epiphytic species. This is the first ecological study of tropical forests that focuses specifically on terrestrial bryophytes. Aim: To investigate the differences between slope and ridge environments in upper montane forests of southern Ecuador in terms of species diversity (richness, abundance), species composition and life forms of terrestrial bryophytes. Methods: We used Non-metric Multidimensional Scaling (NMDS) to group bryophyte relevés by study location, habitat type and exposure class. Species indicator values were calculated and compared for different habitats. Results: In total, 140 species were recorded, the majority being liverworts. NMDS analyses and Mantel correlations clearly separated between slope and ridge relevés, and between sunny and shaded microhabitats on ridges. Bryophyte life forms also showed different distribution patterns in slope and in ridge habitats. Mosses were more prominent in sunny than in shaded microhabitats. Conclusions: Environmental differentiation between ridges and slopes, and small-scale variation in microclimatic conditions caused by differences in exposure, were stronger predictors of species richness and composition than geographical distance between study sites.