Frugivoria e dispers?o de sementes por aves em duas esp?cies de Miconia (Melastomataceae) em uma ?rea de mata atl?ntica na Ilha da Marambaia, RJ

• Autor(a) principal: Antonini, Rafaela Dias
• Data de Publicação: 2007
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UFRRJ
• Texto Completo: https://tede.ufrrj.br/jspui/handle/tede/179
• topic: frugivoria, dispers?o de sementes; aves; Ilha da Marambaia; Melastomataceae; frugivory; seed dispersal; birds; Ecologia

The aim of this study was to analyse the populational structure of Miconia prasina and Miconia calvescens (chapter I), study the visiting birds and its foraging tactics (chapter II) and to evaluate the potential of Ramphocelus bresilius as a seed dispersal of those species (chapter III). This work was developed at Ilha da Marambaia (RJ), where were made 40 25 m2 plots from the edge, distributed in three distances. On each one was registered the number of individuals and measured their BHD and height. The pattern of spatial distribution was determined using the Morisita?s Dispersion Index (Id). Possible differences on the populational structure of the species were verified with Student?s T test, while the frequency of vegetation occupancy from the edge, was tested using Chi-square test. The values of Id indicated a aggregated distribution patternfor both species, being M. prasina more founded inside the forest, while M. calvescens specially on the edge. The population of M. calvescens seems to be formed by young individuals, while the population of M. prasina by older individuals. To analyse the guild os visitors to both species, were made focal-tree like observations for 30 minutes periods, when were registered the visiting birds species, the number of individuals and its foraging tactics. Were calculated the frequency of visits total and for each specie for hour and the similarity of the visitors guild among plant species with the Jaccard Similarity Index (Cj). Miconia prasina was visited for six bird species, specially among september and october. M. calvescens was also visited by six species, specially among July and august. The visitors?guilds showed a low similarity among them, being only two species in comon (Ramphocelus bresilius e Thraupis sayaca). The most frequent species, to both Miconia was R. bresilius. The visits on M. prasina concentrated between 09h and 14h, while that, for M. calvescens, was not found a pattern on the visits period. Species of Melastome family are considered key-species to bird communities, for having long frutification period and big amount of fruits. For the germination experiment, were captured six individuals of R. Bresilius and kept in cages for 24 hours. After that time, were offered 10 ripe fruits of the same species of Miconia, removing their faeces every 15 min and, after the first hour, every 30 min. Seeds removed from the faeces (10 of each interval) were put to germinate in petri dishes with filter papel. Analogously, were made four control units with 25 seeds each. Possible differences on germination times were tested using Mann-Whitney test, and the germination rate were compared using Chi-square test. The higher percentage of germination occurred in seeds eliminated among 45 and 60 minutes after the ingestion for M. calvescens and among 15 and 30 minutes for M. prasina. However, the ingestion of seeds reduced the germination rates for both species, inferring that Ramphocelus bresilius can act as a low efficient dispersal for those plants.