Distribution of Costa Rican epiphytic bromeliads and the Holdridge Life Zone System

Detailed distribution maps for the major bromeliad genera native to Costa Rica were prepared based on the collections in the three largest herbaria of the country and on citations from the literature. Most records are from the montane habitats, probably reflecting the frequent need for moisture by these plants. Vriesea and Guzmania have been collected mostly in moist highlands, Tillandsia and Catopsis show abundance peaks at various altitudes and Aechmea is more restricted to moist lowland habitats. in 1975, Burt-Utley and Utley had hypothesized that the Holdridge Life Zone System should fit the distribution of epiphytic bromeliads because soil (a factor not considered in the System) is not important in their occurrence. However, on average, species were absent in about half of the Life Zones where they were expected to occur according to the Holdridge classification. It is hypothesized that the System failed because epiphytic bromeliad distribution reflects factor interactions rather than humidity, light or temperature individually.