Epiphytes are highly diverse, understudied, important for ecosystem functioning, and threatened by habitat loss and fragmentation. Shade coffee has been demonstrated to be potentially good substitute habitat for vascular epiphytes, but colonization dynamics over time of epiphytes on planted trees in shade coffee systems have not been explored. Our research uses data from 87 shade coffee stands in northern Nicaragua to capture a surrogate chronosequence of tree age from 3 years to ancestral forest trees. We examine epiphyte community assembly across ages at the stand, tree, and tree zone levels, asking how epiphyte communities change over time at each scale and which species and taxonomic groups are the earliest colonizers. We hypothesized that assembly is a nested process with a small subset of early colonizing species arriving first and additional species being added as niche habitats diversify with increasing tree age.
Results/Conclusions
Across all stands, a total of 10,358 vascular epiphytes from 131 distinct morphospecies were recorded in 748 trees. Epiphyte abundance per tree ranged from zero to 478 and increased quadratically with tree diameter. Epiphyte distributions were concentrated on the trunk for smaller size classes, then expanded dramatically in the tree crowns at larger size classes. Our data also show a quadratic relationship between epiphyte species richness and tree size, due both to accumulation of species over time and differentiation of niche habitats within larger trees. Grouping stands by age and origin reveals that epiphyte communities in young shade trees are nested subsets of those in mature trees. Ferns are among the first vascular epiphytes to colonize, followed by atmospheric bromeliads. Orchids colonize later and show a strong preference for the inner canopy of mature shade trees. A small group of early colonizing species can be identified from the total species pool. Our results suggest that newly planted trees in shade coffee farms may eventually serve as valuable habitat for diverse epiphyte communities, but that accumulation of species takes considerable time, so land tenure and maintaining consistent farm management over time are important considerations for conservation goals.