Ecology and population genetics of Cyathea brooksii Maxon (Cyatheaceae)

Cyathea brooksii Maxon is a tree fern reported for Puerto Rico, Hispaniola, and Cuba. The distribution, relative abundance, phenology, population ecology, reproductive biology, propagation, and genetic variability of the species were studied. The historical distribution was determined based on herbarium specimens. Current populations in Puerto Rico were located and each individual was flagged, numbered, and recorded on a site map. In vitro and in situ spore culture experiments were done. Starch gel electrophoresis was conducted to assess genetic variability. In Puerto Rico the species is limited to serpentine soils in the Maricao Commonwealth Forest. Three localities were found within the forest, with a total of 392 individuals. The species grows mostly on shaded slopes along streams. New frond and spore production occur throughout the year. Optimum temperature for spore germination was 25{dollar}spcirc{dollar}C, and the optimum pH was 4.8. The levels of polymorphism and measures of genetic variability for the species were high compared to other ferns and seed plants.