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Journal Article

POPULATION DYNAMICS OF ENCYCLIA TAMPENSIS IN FLORIDA

Ronald J. Larson
Selbyana
Vol. 13 (1992), pp. 50-56
Stable URL: http://www.jstor.org/stable/41759792
Page Count: 7

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Topics: Protocorms, Mortality, Seedlings, Plants, Hammocks, Epiphytes, Rain, Leaves, Population dynamics, Mature plants
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POPULATION DYNAMICS OF ENCYCLIA TAMPENSIS IN FLORIDA
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Abstract

A population of Encyclia 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 1 mm diameter protocorms to flowering plants with up to 30 pseudobulbs (3-20 mm in diameter). Recruitment occurred in three of the 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 protocorms, with the majority surviving > 2 years (mean observed longevity = 21.5 ± 2.2 months). The longest-lived prebulb plant lived > 48 months. Mortality was lowest for plants with pseudobulbs (≈ > 5 years); however, a few of these died. First flowering probably occurred at ≈15 years of age. In December 1989, a severe cold front passed through Florida; temperatures reached—5°C, killing all the orchids. At other central Florida sites, mortality of E. tampensis was high (> 80%). Tillandsia spp., bromeliads (e. g., T. bartrami, T. fasciculata, T. flexuosa, and T. setacea) suffered variable mortality. Tillandsia recúrvala 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 of conservation. Encyclia tampensis fue estudiada en bosque costero "hammock" cerca de Fort Pierce, Florida, por mas de un período de cuatro años (Nov. 1985 a Dec. 1989). Más de 80 orquídeas fueron localizas en los cedros "live oak" (Quercus virginiana) en ramas de 2 m de largo. Las orquídeas variaban de tamaño, desde protocormos de 1 mm de diámetro, hasta plantas en floración con 30 pseudobulbos (3-20 mm en diámetro). La colección de se hizo sólo en tres de los cuatro años del estudio, recolectádose 32 protocormos., La mayoría de éstos sobrevivieron sólo cuatro meses (Je = 4.2, SE ± 1.0 meses); sin embargo, cuatro protocormos vivieron mas de un año, el de mayor duración vivió 17 meses. La mayoría de protocormos aparecieron en el verano pero morían en el otoño o el invierno, aparentemente por desecación. Por otra parte las formas mas maduras de ' prebulbos' (= 2-5 años de edad) fueron mas numerosos y vivieron más, llegando unos hasta sobrevivió 2 años (X = 22.5, SE ± 2.0 meses). El prebulbo que mas sobrevivió alcanzó 46+ meses. La mortalidad fue baja en las plantas con bulbos (=> 5 años), aunque algunas plantas pequeñas murieron. La primera floración probablemente ocurrió entre los 10-15 años. En Diciembre de 1989, un viento severo frío pasó por Florida; las temperaturas alcanzadas fueron de—5°C, aniquilando todas las orquídeas. En otros sitios de la parte central de la Florida, Epidendrum conopeum y Harrisella filiformis, aparentemente no fueron afectadas; bromelias como Tillandsia spp. (T. fasciculata, T. flexuosa, y T. setacea) mostraron una mortalidad variable.

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