Network Structure and Species Roles in Epiphyte–Phorophyte Interactions on a Neotropical Inselberg Woody Vegetation

Using metrics from network theory allows us to understand the structural organization of epiphyte communities and identify the host trees (phorophytes) that are fundamental to their establishment. In this study, we applied ecological network metrics to examine the structure of interactions between vascular epiphytes and phorophytes in a woody inselberg community in southeastern Brazil. The recorded network comprised 30 epiphyte species and 13 phorophyte species, exhibiting a nested structure, low specialization (H2′), low connectance, and low modularity, like other epiphyte–phorophyte networks. The main roles in the network were played by the generalist epiphyte Tillandsia loliacea and the lithophytic phorophytes Tabebuia reticulata and Pseudobombax petropolitanum, which interacted with 100% of the recorded epiphytic species. Epiphyte species were organized vertically into modules that correlate with the ecological zones of the phorophytes, suggesting that their distribution responds to microclimatic variation along the vertical gradient. These results reinforce the importance of particular phorophyte species as key structuring agents of epiphytic communities and highlight their central role in extreme environments such as inselbergs.