PARENT SESSION
Poster Session #46: Seed Production, Recruitment, and Pollination.
Friday, August 10, 2001. Presentation from 10:30 AM to 12:00 PM. Exhibition Hall
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Regeneration in Amazonian floodplain forest.
Moegenburg, Susan1, Castelo Branco Pina, AnaLucia2, 1 2
ABSTRACT- Plant ecologists strive to determine the relative importance of seed versus microsite limitation as factors limiting recruitment of individuals into populations and species into communities. While many studies test for seed versus microsite limitation in upland tropical rainforests, fewer have assessed the factors that limit recruitment into floodplain tropical rainforests, which tend to support fewer species than do their upland counterparts. We used several methods to evaluate factors limiting recruitment into species-poor eastern Amazonian floodplain forest, in which microelevation determined the degree of flooding. We hypothesized that microelevation would determine seed fate. We mapped the distribution of microelevations, of dispersed Euterpe oleracea (Palmae) and Virola surinamensis (Myristicaceae) seeds, and of established seedlings. We also placed E. oleracea seeds at high, intermediate, and low microelevations and followed their survival for 3 years. Very small differences among lower microelevations significantly affected seed survival. However, survival was not positively related to microelevation, because at high elevations biotic processes (e.g., predation) limited survival and establishment. Biotic and abiotic factors thus combined to create a narrow band of regeneration intermediate between high and low elevations. The location of the regeneration band differed, however, between E. oleracea, which has non-buoyant seeds, and V. surinamensis, which has buoyant seeds. Intense competition within these narrow bands of regeneration may help explain the lower tree species diversity typical of tropical floodplain forests.
KEY WORDS: regeneration, floodplains, Amazonia, palms