Reprodução, distribuição e padrões de co-ocorrência em uma comunidade de palmeiras na Amazônia central: Uma abordagem teórica e experimental

Abstract

One of the main concerns of community ecology is to determine which factors affect species distribution. Starting from the premise that fruit production is the last step of true establishment, we match environmental gradients and the experimental approaches with help from phylogenetic tools to bring light into the mechanisms influencing palm distribution patterns in a terra firme forest in central Amazonia. We sampled 30 PPBio standardized plots of 1 ha each at Ducke Reserve near Manaus, where every individual from nine species was identified, marked and counted. Every month, marked palms were monitored for fruit presence and some focal individuals had their fruits counted. Besides, we used data from the whole palm community available in a data set from 72 plots in the same area to analyze the phylogenetic community structure. Additionally, we conducted a seed-sowing experiment with two species of Attalea in 30 plots. Overall, most of nine species monitored presented some degree of restriction in at least one developmental phase along the clay content gradient, with fruiting individuals more restricted. Even so, some species produce fruits regardless of the gradient position such as Euterpe precatoria, Iriartela setigera and Oenocarpus minor. We did not find phylogenetic structure in the local palm community. Additionally, the morphologic/reproductive traits were not conservative, but labile and not spatially structured. However, in bottomlands more similar individuals co-occur more than expected by chance. Finally, the sowed seeds of Attalea did germinate regardless of the gradient position showing a distribution pattern more related to dispersal limitation than to environmental control. These results suggest important conclusions about the factors affecting the palm distribution showing that information that do not consider fruit production and species relatedness may lead to biased conclusions compromising choise of a appropriate site for conservation purposes.