Diversity and species associations in cryptogam communities along a pedoenvironmental gradient on Elephant Island, Maritime Antarctica

Abstract

The Maritime Antarctica region has terrestrial ecosystems dominated by lichens and mosses, representing important ecological indicators of climate change. However, little is known about environmental factors that shape regional cryptogam communities at local scale. In this study we analyse changes in species richness, species composition and coverage of representative cryptogam communities across a pedoenvironmental gradient in Maritime Antarctica. We hypothesized that soil texture and chemical properties shape variations in species richness and composition. We selected fifteen different pedoenvironments, where 20 plots (20 × 20 cm) were sampled for obtaining phytosociological parameters of cryptogamous communities, and in each plot a composite topsoil sample was collected to determine chemical and physical soil properties. We then evaluated the main effects of soil attributes on the richness and composition of cryptogam species using direct gradient analysis and linear models. The ecological value of species was determined, allowing to identify the type of plant community and species associations in each pedoenvironment. Differences in species composition, richness and coverage were detected along the pedoenvironmental gradient. The model analysis showed that soil fertility has significant effects on species composition, but not on species richness. Based on gradient analysis, variability on soil fertility and nutrient contents were important pedoenvironmental filters for cryptogam communities in Maritime Antarctica. This study reveals that small-scale heterogeneity contributes to specific associations along pedoenvironmental gradients. We conclude that soil attributes drive the composition pattern of cryptogam species and also the type of communities present.