Edge effects are ubiquitous landscape processes influencing over 70% of forest cover worldwide. However, little is known about how edge effects influence the vertical stratification of communities in forest fragments. We combined a spatially implicit and a spatially explicit approach to quantify the magnitude and extent of edge effects on canopy and understorey epiphytic plants in the Brazilian Atlantic Forest. Within the human-modified landscape, species richness, species abundance and community composition remained practically unchanged along the interior-edge gradient, pointing to severe biotic homogenisation at all strata. This is because the extent of edge effects reached at least 500 m, potentially leaving just 0.24% of the studied landscape unaffected by edges. We extrapolated our findings to the entire Atlantic Forest and found that just 19.4% of the total existing area is likely unaffected by edge effects and provide suitable habitat conditions for forest-dependent epiphytes. Our results suggest that the resources provided by the current forest cover might be insufficient to support the future of epiphyte communities. Preserving large continuous ‘intact’ forests is probably the only effective conservation strategy for vascular epiphytes.

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Tropical montane forests (TMF) are characterised by high endemism, species richness and turnover across elevations. A key question is how niche‐based processes, via adaptation of species to local environmental conditions, and neutral‐based processes from dispersal limitation shape community composition at different spatial scales across human‐modified landscapes. We expect that (1) communities are highly distinct even within the same habitat type and (2) niche‐based processes play the main role in compositional turnover. To address these expectations, we investigated the compositional turnover of orchids, one of the most prominent floristic elements of TMFs. We sampled orchids in 332 plots spanning over 270 km in the eastern Colombian Andes. Plots ranged between elevations of 1160–3750 m. We used two different spatial extents (whole gradient and two elevational bands), two grains of analysis for the first expectation (regional and local) and two spatial grains for the second expectation (broad and fine scales based on Moran's Eigenvector Maps [MEMs]). We found 331 orchid species in 171 (51%) plots. We found a strong pattern of high compositional turnover across scales (>72% of total beta diversity is given by species turnover), with 87.5% of the total species pool occurring in fewer than five plots, supporting our first expectation. Contrary to our second expectation, we found that community composition is mainly driven by geographical distance, while the relative influence of elevation, environmental variables and their combined fractions were negligible across habitats and spatial scales, rejecting niche‐based processes. Synthesis. High compositional turnover, even across habitats with the highest degree of human intervention, suggests that both forest‐dwelling and open‐habitat species do not easily disperse across habitats. Species dispersal is the major force of orchid community turnover and might be strongly dependent upon macroevolutionary processes and species life‐history traits over multiple scales. Dispersal limitation also draws attention to the importance of preserving habitat connectivity to halt biodiversity losses.

Mormolyca cleistogama has its occurrence unknown in São Paulo state, although widely distributed in South America. In this study, based in field collection, we confirmed the occurrence of M. cleistogama in São Paulo state, Brazil. Morphological descriptions, color images and comparison with the closely related taxon, M. rufescens, are presented.

Extensive fieldwork carried out on the Andean forests of Colombia resulted in the discovery of Lepanthes cordillerana, described here as a novel taxon. The new species is most similar to Lepanthes teres from Ecuador, from which it can be easily distinguished by the ciliated margins of the leaf, the oblong-acute lower lobe of the petals and the capitate, cuneate basally, apically caved, villose appendix. Despite its wide distribution across the three Colombian mountain ranges, a landscape analysis shows that 50% of the recorded wild populations of the endemic Lepanthes cordillerana are under threat of habitat loss and landscape fragmentation. Conservation efforts should be directed to reduce landscape scale threats to their populations.