Epiphyte assemblages respond to host life-form independently of variation in microclimate in lower montane cloud forest in Panama

Abstract

Abstract:We investigated the effects of host tree on epiphyte diversity, controlling for microclimate. We measured the light profiles of the lower trunks of 20 individuals, each from three host groups (tree ferns, dicots, palms) occupying the understorey in a tropical montane forest in Panama. The per cent cover and species richness of vascular and non-vascular epiphytes were surveyed on the lower trunks of each understorey host. Light varied considerably between trees (5–21% total transmitted light) but mean light level did not vary between types of host. Light was not significant as a covariate with host in any model. Tree ferns had higher covers than dicots and palms of filmy ferns (15%, 0.02% and 0.2%), other ferns (7%, 0% and 0.5%) and other vascular epiphytes (16%, 3% and 3.4%), and greater species richness of vascular epiphytes (filmy ferns: 3, 0.4 and 0.5; other ferns: 2, 0.2 and 0; other vascular: 7, 2 and 2). Dicots had a higher cover of liverworts (53%) than palms (18%) and tree ferns (27%). Palms and tree ferns were the compositional extremes. We conclude that the differences in species composition and cover between the three host groups relate better to physical differences between hosts than differences in light climate.

Phylogenetic diversity and the structure of host-epiphyte interactions across the Neotropics

“…In other words, if a host plant has a phylogenetically diverse set of associated epiphytes, closely related host species are also likely to show high epiphyte PD. Some studies have uncovered proximate mechanisms that might influence the presence of different epiphyte species, such as habitat conditions, availability of propagules, their dispersal characteristics and requirements for seedling establishment ( Cascante-Marín et al, 2006 ; Burns, 2007 ; Ceballos, Chacoff & Malizia, 2016 ; Francisco et al, 2018 ; Francisco et al, 2019 ; Zotarelli et al, 2019 ), as well as the physical characteristics of the host plants ( Sanger & Kirkpatrick, 2014 ). One might therefore hypothesize that these properties of host plants might predict epiphyte PD in a way that is independent of host evolutionary distinctiveness.…”