DISTRIBUTION OF COSTA-RICAN EPIPHYTIC BROMELIADS AND THE HOLDRIDGE LIFE ZONE SYSTEM

Detailed distribution maps for the major bromeliad genera native to Co sta Rica were prepared based on the collections in the three largest h erbaria of the country and on citations from the literature. Most reco rds are from the montane habitats, probably reflecting the frequent ne ed for moisture by these plants. Vriesea and Guzmania have been collec ted mostly in moist highlands, Tillandsia and Catopsis show abundance peaks at various altitudes and Aechmea is more restricted to moist low land habitats. in 1975, Burt-Utley and Utley had hypothesized that the Holdridge Life Zone System should fit the distribution of epiphytic b romeliads because soil (a factor not considered in the System) is not important in their occurrence. However, on average, species were absen t in about half of the Life Zones where they were expected to occur ac cording to the Holdridge classification. It is hypothesized that the S ystem failed because epiphytic bromeliad distribution reflects factor interactions rather than humidity, light or temperature individually.