Habitat preference of the epiphyte Tillandsia recurvata (Bromeliaceae) in a semi-desert environment in Central Mexico

Tillandsia recurvata L. is an atmospheric epiphyte that occupies tree canopies in many parts of tropical America. We investigated the host preferences of this species by analyzing its occurrence on trees in a 1-ha plot in a semi-desert environment in Mexico. Additionally, we carried out germination experiments and recorded seedling survival and growth in different microsites on the three preferred host species. Our results indicate that T. recurvata occupies the crowns of certain host species (Prosopis laevigata (Humb. & Bonpl. ex Willd.) M.C. Harms, Acacia bilimekii Macbr., and Cercidium praecox (Ruiz & Pav.) Harms) with a higher frequency than expected by chance. In addition to species identity, tree size affected the probability of being occupied: small trees were occupied with lower frequencies and with lower densities than larger ones. On the other hand, distance to the nearest colonized tree was not related to the probability of a tree being occupied. Seed germination ranged from 0% to 7.5% and did not differ among the three host species tested. However, both seed germination and seedling growth were higher in the outer and upper parts of tree crowns. Given the patchy distribution of this epiphyte, we propose this system may be viewed as a metapopulation in which patch suitability varies according to host identity and size.