POPULATION DYNAMICS OF ENCYCLIA TAMPENSIS IN FLORIDA

Abstract

A population ofEncyclia tampensis was studied in a hammock near Fort Pierce, Florida, U.S.A. between November 1985 and January 1990. Nearly 100 orchids were recorded from a single live oak (Quercus virginiana) limb 2 m in length. Orchids ranged in size from I mm diameter protocorms to flowering plants with up to 30 pseudobu1bs (3-20 mm in diameter). Recruitment occurred in three ofthe four years, resulting in a total of 36 protocorms. Most protocorms were short-lived (4.4 ± 0.8 months); however, four lived more than one year and the oldest lived for 17 months. "Protocorms" first appeared in early summer and died in fall and winter, apparently from desiccation. Older "prebulb" seedlings (:::;2- 5 years old) were the most numerous growth stage and lived longer than protocorrns, with the majority surviving>2 years (mean observed longevity = 21.S ± 2.2 months). The longest-lived prebulb plant lived >48 months. Mortality was lowest for plants with pseudobulbs (:::; > 5 years); however, a few ofthese died. First flowering probably occurred at:::; 15 years ofage. In December 1989, a severe cold front passed through Florida; temperatures reached - 5°C, killing all the orchids. At other central Florida sites, mortality ofE. tampensis was high (>80%). Tillandsia spp., bromeliads (e.g., T. bartrami, T. fasciculata, T. jlexuosa, and T. setacea) suffered variable mortality. Tillandsia recurvata showed some mortality at exposed sites, but T. usneoides was unaffected. These observations suggest that meteorological factors (e.g., rainfall and low temperatures) can significantly affect epiphytes in Florida and must be considered in the context ofconservation.