Relative influence of relatedness, conspecific density and microhabitat on seedling survival and growth of an animal-dispersed Neotropical palm, Oenocarpus bataua

Abstract

We report on a 6-year, field-based experiment in north-western Ecuador, evaluating the relative importance of relatedness, conspecific density and microhabitat on the growth and survival of seedlings of an ecologically and economically important palm, Oenocarpus bataua. We planted O. bataua seedlings in high-density seed deposition sites (leks) of the long-wattled umbrellabird (Cephalopterus penduliger) and randomly selected control sites. We analysed seedling performance in relation to conspecific relatedness, conspecific density and microhabitat. Among the parameters we measured, light availability was the most important determinant for survival and growth. Higher relatedness of neighbouring experimental seedlings and higher conspecific seedling densities were both associated with reduced growth, but did not influence survival, even in umbrellabird leks. These findings are consistent with a survival advantage of umbrellabird dispersal into lek sites (i.e. directed dispersal) that counterbalances negative density-dependent processes expected to occur at these high-density deposition sites. This study highlights the importance of a multi-tiered approach to understanding palm demography and underlines the importance of seed disperser behaviour in determining seedling fate.