Phenology, seed dispersal and difficulties in natural recruitment

13 páginas, 5 figuras, 2 tablas.

commercial species. This study focused on a widely exploited Neotropical canopy species, Pachira quinata (Malvaceae), at the southernmost, wettest limit of its natural distribution, in the Colombian Amazonia. We studied phenological patterns, seed production and natural densities; assessed the importance of seed dispersal and density-dependent effects on recruitment, using field experiments. At this seasonal forest P. quinata was overrepresented by large adult trees and had very low recruitment caused by the combination of low fruit production, high seed predation and very high seedling mortality under continuous canopies mostly due to damping off pathogens. There was no evidence of negative distance or density effects on recruitment, but a clear requirement of canopy gaps for seedling survival and growth, where pathogen incidence was drastically reduced. In spite of the strong dependence on light for survival of seedlings, seeds germinated readily in the dark. At the study site, the population of P. quinata appeared to be declining, likely because recruitment depended on the rare combination of large gap formation with the presence of reproductive trees nearby. The recruitment biology of this species makes it very vulnerable to any type of logging in natural populations.

We thank Carlos Mejía for continuous support during field work. Ramiro Montealegre shared with us his knowledge on local P. quinata. Mauricio Alvarez initially planted the seedlings that served us for two-year monitoring. Financial support was provided by a WCS-FES-Instituto von Humboldt undergraduate research grant to MCC.

Peer reviewed