Distribution of Tree Ferns (Cyatheaceae) across the Successional Mosaic in an Andean Cloud Forest, Narino, Colombia

Abstract

Approximately eleven species of tree ferns (Cyatheaceae, Dicksonia, and Lophosoria) occur in the cloud forest of La Reserva Natural La Planada, Narifo, Colombia. We used 500 m2 (50X10 m) plots, 10 each in primary forest, secondary forest, and abandoned pasture, to measure the density and species distribution of tree ferns. Abandoned pasture and secondary forest had approximately equal tree fern densities, with density in primary forest significantly lower. Species richness was highest in secondary forest due to the mixture of early and late successional species. Pasture and secondary forest habitats were dominated by Cyathea caracasana; higher diversity recorded in abandoned pasture is due to high relative abundances of two subordinate species: Lophosoria quadripinnata and Dicksonia sellowiana. Primary forest was dominated by a single species, Cyathea planadae, with very low relative abundance of the other species recorded. The dominance transition during regeneration appears to begin after approximately 20 years of re- growth, suggesting that the disturbance mosaic and the resulting environmental heterogeneity in Andean forests is important in maintaining species diversity in tree ferns. Two recommendations for conservation emerge: 1) Conservation of tree fern diversity depends on the maintenance of a variety of successional habitats within the forest; 2) Tree ferns are an important component of species that colonize abandoned open sites in Andean forests. Their rapid growth rate and pref- erence for open habitat suggest that some tree fern species may be useful in restoration strategies in cloud forests.