Abstract

Ferns are the dominant epiphytic flora of the neotropical forests of Puerto Rico. The goal of this study is to identify anatomical features associated with species distribution among epiphytic ferns inhabiting the first three meters of a tree trunk, targeting eighteen of the most common species identified from a 2012 survey at El Yunque National Park, Puerto Rico. We collected an adult specimen of each species during our 2015 field work at El Verde Station, Luquillo LTER. At the field station, we dissected each specimen into leaf, stipe, and rhizome sections, photographed the largest leaf, measured the major dimensions (length and width) of each organ, and preserved them for transport to GVSU. To add statistical power to the 2012 distribution data, we also conducted a “blast” survey of the occurrence of the target (18) species on the first, second, or third meter of 300 trees. At GVSU, the preserved organ sections were macerated to separate conductive cells, permanent slides produced, and up to ten replicates of each cell type found were photographed for measurement of key hydraulic traits (e.g., conduit length and width, pit area, pit aperture, and pit frequency) that we suspect determine occurrence along the vertical moisture and exposure gradient on a tree. At the time of this report all species have been macerated at least once and approximately 60% of the 540 (anticipated) cell (including both type and replicate) have been successfully macerated, mounted on slides, and photographed. Some species have presented unexpected problems such as obstructive carbohydrate-protein clouding of slides and dehydration of the mounting medium (which is a product flaw). These problems were solved during Fall 2015 and we expect to complete the remainder of data collection during Winter 2015.