How does the pedoenvironmental gradient shape non-vascular species assemblages and community structures in Maritime Antarctica?

The main terrestrial ecosystems dominated by lichens and mosses, which represent important ecological indicators of climatic changes in high polar latitudes, are found in the Antarctic continent. However, little is known about how environmental filtering shapes cryptogamic communities’ assemblages at fine-scale. In this study, we analysed changes in non-vascular species richness, species composition and plant coverage along a pedoenvironmental gradient in Maritime Antarctica. We hypothesized that pedoenvironmental filters (i.e. soil texture and chemistry properties) drive the non-vascular assembly community. We classified soils according to the World Reference Base for Soil Resources, selecting ten different pedoenvironments at fine-scale. The plant inventory data from 206 plots across these pedoenvironments was used to evaluate the main effect of plant coverage, soil texture and soil chemistry on non-vascular species richness and composition. The ecological value of the species was determined and the type of community it occurred in was characterized, then the associations of the species were classified in each pedoenvironment. Differences in species richness, species composition and plant coverage were detected along the pedoenvironmental gradient. However, plant coverage, soil chemistry, soil texture and soil variables did not affect species richness and species composition, with the exception of clay content that was particularly an important predictor of species composition. High pedoenvironmental filtering apparently has no effect on species richness but determined differences in species composition. Therefore, we assumed that pedoenvironmental filtering determined high beta diversity in this island from maritime Antarctica. This study reveals that fine scale heterogeneity contributes to specific species associations along a pedoenvironmental gradient; thus, pedoenvironmental filtering not only determines diversity pattern in non-vascular plants, but also type of communities.Keys words: lichens; pedoenvironmental filtering; microsite conditions; mosses; plant coverage.