Tropical deforestation is a progressive process resulting in the conversion of rain forest into a mosaic of mature forest fragments, pasture, and degraded habitat. Understanding the long-term effects of habitat fragmentation on tropical plant community structure is critical to predicting how alterations to the landscape will impact tropical biodiversity. The objective of this study was to examine fragmentation effects on the composition, abundance, and species richness of epiphyllous (leaf-inhabiting) bryophytes. I conducted this research in an experimentally fragmented forest reserve in central Amazonia where data on the distribution and abundance of 65 bryophyte taxa were analyzed from 16 1-ha sample plots located in continuous forest and fragments. Epiphyll communities inhabiting small (1- and 10-ha) fragments exhibited lower species richness, abundance, and among-site compositional variation than those from 100-ha fragments and continuous forest plots. Reduced epiphyll diversity in small fragments is not simply a statistical artifact of low epiphyll densities, but rather due to a disproportionate loss of regionally common taxa. In contrast, rare taxa responded marginally to fragmentation, and in most cases were more abundant in fragments than in continuous forest habitat. Because epiphyllous bryophytes rapidly establish species-rich communities on spatially discrete habitat patches, they are an ideal plant group for addressing the long-term (multigeneration) impact of habitat fragmentation on plant communities.
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