Current and future tree ferns distribution and diversity patterns in subtropical Atlantic Forest

In "sp_data.csv" file, we gathered 1,167 tree ferns records related to 15 species, from the literature and herbaria (using SpeciesLink - http://splink.cria.org and GBIF Global Biodiversity Information Facility - https://www.gbif.org). We used "SDM" R-script to predict current and future distributions of each tree fern species, based on occurrence records and bioclimatic variables. Our SDMs were formulated using the sdm R-package, through five different algorithms. To avoid biases created by choosing a single statistical algorithm, we built a single final model through an ensemble approach. Using the "beta" script and species maps, we calculated the β-diversity as the total variance of the community (Total β-diversity, or BDTOTAL; sensu Legendre & De Cáceres 2013) and it was subsequently decomposed in Local Contributions to β-Diversity (LCBD). We calculated BDTOTAL based on the Jaccard dissimilarity coefficient (1- similarity). Then, the LCBD was determined based on the partition of BDTOTAL between the cells (Legendre & De Cáceres 2013). The significance of the LCBD values for each cell was obtained through 999 permutations, where the species are distributed randomly and independently along the grid and the LCBD values are calculated for each random distribution. Significant LCBD values were those with p-value < 0.05. We also followed Legendre (2014) by partitioning the BDTOTAL ​​in species replacement and richness difference components. All β-diversity metrics were calculated with the adespatial R-package using the functions beta.div and beta.div.comp

Correlation of variations in species abundance of Atlantic forests regenerating on abandoned pastures with different environmental and spatial variables

The conversion of native forests into pastures is still a common practice in Brazil. Abandoned pastures have great potential for natural regeneration and therefore could play an important role in meeting the enormous demand for forest restoration. Few studies, however, have investigated the extent to which spatially-structured environmental variables and community structure are correlated with the variation in species abundance of regenerating forests on abandoned pastures. Therefore, we aimed to determine whether environmental and spatial variables were capable of explaining the variation in abundance of woody species on abandoned pastures in the subtropical Atlantic Forest. We systematically distributed 45 sample plots with size and inclusion criteria that changed according to the vegetation layer in three different abandoned pastures. In general, most of the variation in species abundance that our models were able to explain was correlated with spatially-unstructured physical-chemical soil properties. A smaller part of the variation was correlated with spatially-structured soil variables and topography-related variables. An even smaller portion of the variation was spatially-structured but was not correlated with spatially-structured environmental variables. Therefore, our results suggest that the variation in species abundance of regenerating subtropical Atlantic forests on abandoned pastures is more closely related to niche-based processes mediated by environmental variables than to stochastic spatial processes.</p