Plant reproductive systems in a secondary deciduous forest remnant in the Caracas valley, Venezuela

Plant sexual and breeding systems, temporal variations in sex expression, and herkogamy were investigated. Of the 294 plant species surveyed, 73.8% were hermaphroditic, 18.7% monoecious, and 7.5% dioecious. The frequency of adichogamy (71.7%) was higher than that of dichogamy (28.3%) in hermaphrodite and monoecious species, and protandry was more common than protogyny. There was a higher proportion of herkogamous species (80.6%) to non-herkogamous species. Dioecious species were associated with trees, frugivory, and late seral stages, and monoecy was associated with herbaceous life forms, the C-4 metabolism, and disturbed habitats. Outbreeding systems were the most abundant in a subsample of 84 plant species: no agamospermy (98.4%), non-spontaneous self-pollination (64.3%), xenogamy (65.4%), and self-incompatibility (39.3%), followed by mixed breeding systems. Non-spontaneous self-pollinated and xenogamous plants were mostly woody species from undisturbed areas dispersed either by frugivores or abiotically. Self-incompatibility was also mainly a strategy of woody species that flowered during the dry period. Mixed breeding strategies: partial spontaneous self-pollination, partial xenogamy, and partial self-incompatibility were more frequent in disturbed areas. Thus, outbreeding was the main form of reproduction in the undisturbed forest. We recommend that these forest relics be maintained as reservoirs in order to protect them in their original state.