Bryophytes of a Brazilian seasonally dry tropical forest: an overview of diversity and environmental drivers

Abstract

We analyzed the diversity (richness and composition) and distribution patterns of bryophytes in the Caatinga, exploring how environmental variables affect the communities in this unique Brazilian phytogeographic domain. We built a comprehensive database of bryophyte occurrences using online datasets (WorldClim 2.1 and Global Aridity Index and Potential Evapotranspiration Database 3), keeping only records identified at the species level by specialists with accurate geographic coordinates. For each locality, 19 bioclimatic variables, elevation data, and the aridity index were compiled. Generalized Linear Mixed Models (GLMM) and Permutational Multivariate Analysis of Variance (PERMANOVA) were applied to determine the effects of environmental variables on species diversity. Undersampling of bryophytes was detected across most of the Caatinga; nevertheless, an astonishingly high number of taxa (491) was found. Elevation, moisture (BIO15 and AI), and temperature (BIO2 and BIO4) indices were key factors in modeling species richness and composition of bryophyte communities in this region. Our results demonstrate that the Caatinga is still a neglected domain in floristic and ecological studies of bryophytes and that the relationship between the diversity of this group and environmental variables on a macro-scale is complex. A holistic environmental analysis is needed to understand the structuring of bryophyte communities in Seasonally Dry Tropical Forests.