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Bromeliads are a numerous family of vascular epiphytes, though only one epiphytic species inhabits South-American temperate rainforests: the endemic Fascicularia bicolor. This bromeliad is an important driver of canopy biodiversity, but attributes of its hosts are mostly unknown. Here we report (i) the tree species colonized by F. bicolor, (ii) the relationship between tree size and presence of F. bicolor and (iii) the relation between tree size and the number of mats of F. bicolor inhabiting each colonized tree. We sampled 231 trees in seven forest plots recording their species, diameter, heights, and the number of F. bicolor mats growing on them. The dataset was analyzed with a zero-inflated model to relate host tree attributes with F. bicolor occurrence and abundance in a single statistical approach. The occurrence and abundance of F. bicolor depend on host-species identity and diameter. F. bicolor colonization in slow-growing trees started at smaller DBH than that required for other tree species. Nonetheless, the overall occurrence of F. bicolor relies on large trees above 50 cm DBH for most host species. The number of mats occurring on each colonized tree depends on the interaction between tree height and species suggesting the importance of space available for colonization along the tree-trunk, and differential effects due to species’ traits. Currently, large trees and old-growth forests are scarce within the distribution range of F. bicolor, which could seriously affect the long-term conservation of this endemic epiphyte, along with the canopy properties and species associated with it.

Premise: Approximately 14% of all fern species have physiologically active chlorophyllous spores that are much more short-lived than the more common and dormant achlorophyllous spores. Most chlorophyllous-spored species (70%) are epiphytes and account for almost 37% of all epiphytic ferns. Chlorophyllous-spored ferns are also overrepresented among fern species in habitats with waterlogged soils, of which nearly 60% have chlorophyllous spores. Ferns in these disparate habitat types also have a low incidence of mycorrhizal associations. We therefore hypothesized that autotrophic chlorophyllous spores represent an adaptation of ferns to habitats with scarce mycorrhizal associations., Methods: We evaluated the coevolution of chlorophyllous spores and mycorrhizal associations in ferns and their relation to habitat type using phylogenetic comparative methods., Results: Although we did not find support for the coevolution of spore type and mycorrhizal associations, we did find that chlorophyllous spores and the absence of mycorrhizal associations have coevolved with epiphytic and waterlogged habitats. Transition rates to epiphytic and waterlogged habitats were significantly higher in species with chlorophyllous spores compared to achlorophyllous lineages., Conclusions: Spore type and mycorrhizal associations appear to play important roles in the radiation of ferns into different habitat types. Future work should focus on clarifying the functional significance of these associations., (© 2022 The Authors. American Journal of Botany published by Wiley Periodicals LLC on behalf of Botanical Society of America.)