The Influence of Host Tree Species on the Distribution of Epiphytic Bromeliads in Experimental Monospecific Plantations, La Selva, Costa Rica1

Epiphytes perform critical functions in primary tropical forests, but their ecological roles have only rarely been studied in secondary forests or in forest plantations. We assessed the composition and distribution of epiphytic bromeliad communities in four- and eight-year-old replicated experimental monospecific tree plantations (3 species) at the La Selva Biological Station, Costa Rica. The bromeliad communities of these stands are dominated by two species, Guzmania monostachya (L.) Rusby ex. Mez and Vriesea gladioliflora (H. Wendl.) Antoine. We identified bromeliads on over 700 trees and estimated their biomass and leaf area. Mean bromeliad biomass ranged from 2 to 8 g/tree in the four-year-old plots and from 20 to 94 g/tree in the eight-year-old plots. The mean bromeliad leaf area ranged between 104 and 704 cm2/tree and from 1600 to 8500 cm2/tree in the four- and eight-year-old plots, respectively. Although bromeliads accounted for less than 2 percent of the total foliar biomass and leaf area in both four-year-old and eight-year-old plots, the biomass of bromeliads exhibited a 5- to 46-fold increase between the four-year-old and eight-year-old plots, respectively. Bromeliads showed clear patterns of host tree preference, which may be attributed to host tree characteristics that differentially favor recruitment and survivorship. Between four and eight years of growth, differences among host tree species with respect to the amount of available host tree woody biomass, host tree foliar biomass, and host tree leaf surface area were positively correlated with the abundance of epiphytic bromeliads.