Population structure and sex ratio in Ocotea notata (Lauraceae) from a coastal sandy plain in Southeastern Brazil

Abstract

The Environmental Protection Area Setiba corresponds to the buffer zone of the State Park Paulo César Vinha. It was about 12.960 of which 7.500 hectares are terrestrial and the rest in the marine environment. In an open shruby vegetação, periodically flooded, we analyzed the structure and sex ratio of a population of Ocotea notata, Lauraceae, in order to undersatand the population dynamics and to investigate if the spatial pattern led male and female morphs close enough to ensure fruit production. A total of 50 plots of 100m² and 7 plots of 16m², totaling 5112 square meter in size. For all sampled individual, Cartesian ordinates were recorded for its location in the sample space. The criterion for inclusion of individuals in the sample was rooting and was measured stem diameter at ground level and height of each individual, both in scale in centimeters. In addition, we recorded floral visitors and the presence of flowers and fruit at different stages of maturation. The species is dioecious, shrubby habit, and the area sampled there is a predominance of male over female subjects at a ration of 11:1, and the population studied has a random spatial pattern. The flowers exhibit sexual dimorphism beyond the reproductive structures, because the male have a plain receptacle, while the female ones are slightly tapered. There was no fruit production in female flowers protected from pollinators, indicating that the species is not agamospermous. The flowering period includes February to June and fruit ripening occurs between October and November. The flowers are samller than 5mm, cream colored, soft and fragrant are visited by a guild of generalist insects, among them the family Syrphidae flies, small bees of the families Halictidae and Anthophoridae. Not all female subjects were fruitful, but those who have bborne fruit produced much fruit, probably due to the activity of pollinators, which tend to focus on the flowers in an individual rather than dispersed among flowering individuals of the population. The population is well distributed throughout the age groups in addition to presenting a random distribution pattern.