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Wind dispersal and 1-year survival of Vataireopsis iglesiasii (Fabaceae) seedlings in a Neotropical lowland rain forest

Abstract:

Populations of many tropical tree species are regulated by negative distance- and density-dependent processes (NDD), yet most studies on the effects of conspecific seedling and adult neighbors on seedling survival have focused on animal-dispersed species. Species with seeds dispersed by wind may not be moved as far on average as seeds dispersed by animals, but some seeds may be dispersed a lot further, suggesting that knowledge of dispersal mechanism may help in our understanding of NDD. In this study, we took advantage of a high-fecundity reproductive event that occurred for an individual isolated canopy tree of Vataireopsis iglesiasii in a tropical lowland rain forest site in Amazonian Ecuador to document seed dispersal and seedling survival to 1-year post-dispersal. Most seeds did not disperse far: 86% of germinated seedlings were found within 100 m. Mortality was high: only 49 of the 1732 monitored seedlings survived one year and only five survived a further four years. We found a significant negative effect of conspecific seedling density (but no effect of distance from the parent tree) on 1-year survival. Rare long-distance dispersal events may increase the probability of a seed reaching specific habitats, such as high-light patches, and surviving beyond one year, thereby shifting the population recruitment curve outwards away from adult trees and maintaining diversity in species-rich forests. Abstract in Spanish is available with online material.