Fenologia e frugivoria por aves em Miconia calvescens e M. prasina (Melastomataceae): influência do conteúdo de carboidratos dos frutos na composição e frequência de visitação da assembleia de aves consumidoras

Abstract

Determining the factors directioning the fruit selection by birds is an important theme to ecological studies. Phenological registers added to frugivory observations are necessary to a better understanding of the bird-plant interaction dynamics. The present dissertation, divided in two chapters, approached the phenology and fruit consumption by birds in two plant species Miconia calvescens e M. prasina. The goals of chapter one were: describe, analyze and compare the reproductive phenology of Miconia calvescens e Miconia prasina and estimate the availability of fruits of each species. For chapter two, the goals were: determine the bird guild visiting both species, evaluate which species has the higher carbohydrate content in the pulp, verify the existence of a correlation between the nutritional value of the pulp and the richness of the guild, as well as the frequency of visitation, observe if the production of carbohydrates in the fruits varies throughout the day and observe if the peak of bird activity matches the peak of carbohydrate production. The study was developed from January to December 2014 in an Atlantic Forest edge stretch, situated in Ilha Grande, RJ. It were marked five individuals of each species, distant 200m from each other. The phenological registers were made monthly and the intensity of buds, flowers, immature and ripe fruits was estimated by the activity index and the Fournier index. To analyze the guild of visitors, it was made focal-tree like observations, from 06:00am to 06:00pm. It was calculated the frequencies of total visitations for each species by hour and also the similarity of the visitors guild among the plant species with the Jaccard Similarity Index (Cj). To analyze the carbohydrate content, immature fruits (n=10) and ripe fruits (n=10) were collected every four hours, frozen and then lyophilized. The emition of buts in M. calvescens occurred between January and May, peak in February to M. prasina. Miconia calvescens showed flowers from January to September. In M. prasina the same pattern of but arising was observed to flowers throughout the year, but with less intensity. The production of immature fruits in M. calvescens was long, from February to November. The peak of production of immature fruits in M. prasina was from April to June. Ripe fruits were available from May to August in M. prasina, and from August to December in M. calvescens. The fruit availability in M. prasina was significantly higher. Miconia prasina was visited by 23 bird species while M. calvescens was visited by13 bird species. Lanio cristatus was the species that made the higher number of visitation to M. prasina, while in M. calvescens Ramphocelus bresilius was the species with the higher frequency of visitation. The peak of visitation occurred in July to M.prasina and November to M. calvescens. The peak of activity occurred between 10:00am to 11:00am. It wasn t observed differences in the carbohydrate production along the day. The mean carbohydrates present in the fruits were glucose, fructose and sucrose. Miconia prasina had more glucose and fructose than M. calvescens, while this last one had more sucrose