Estrutura da taxocenose de Bromeliaceae em duas áreas de restinga da Ilha da Marambaia, Baía de Sepetiba, RJ.

Abstract

Habitats characteristic of the Brazilian coast, the restingas are ecosystems associated with the Atlantic Forest Domain and are characterized by having mesoclimatic conditions considered extreme, and suffer from intense human pressure. Nevertheless, they have great biological diversity, the Bromeliaceae being one of the most representative of these habitats. This study aimed to evaluate the composition, richness and assemblage structure of Bromeliaceae in two areas of restinga located on the island of Marambaia, Mangaratiba, RJ. We established 50 plots of 100 m2 on each of two areas: the Restinga of Praia da Armação (RPA) and the Restinga da Praia Grande (RPG). These plots were placed in lines parallel to the beach with 10 meters apart. In each plot were recorded richness and abundance of epiphytic and terrestrial bromeliads and measured the morphometric characteristics of the host tree, as well as vertical and horizontal distributions of epiphytic species. We sampled 11 species of bromeliads and three new records for Marambaia, bringing the richness of this locality for 21 species of Bromeliaceae, considered a high value of wealth. Most of the species is included on some level of threat according to IUCN, which characterizes the Marambaia Island as an important conservation site for the family. The Island had low similarity with other areas of restinga of Rio de Janeiro and this can be attributed to its geographical location in relation to these areas and the fact it is an island region. Neoregelia cruenta and Tillandsia stricta are the most abundant and are the ones with the highest frequency of occurrence, which is directly related to different reproductive strategies of these species. The specific physiological needs, like dispersion and structural complexity of habitat caused if there were differences in the occupation of phorophytes by epiphytic species. Already aggregated distribution of all species is related to the mechanism of occupation of the environment used by plants and the quality of different substrates provided by the environment and the host tree. In general, the species tend to avoid the sampling units in accordance mainly with the heterogeneity of the habitat but, however, tend to co-exist in phorophytes once occupied the height classes differently. In this study, none of the morphometric parameters of the host tree explained the variations in the parameters of assemblage richness and abundance of bromeliads, indicating that other variables should better explain these relationships.