Biogeografia de Epífitas Vasculares na Serra da Mantiqueira, Sudeste do Brasil

Abstract

A fundamental issue for biogeography and ecology is to understand and map the species distribution, which also provides subsidies for actions of conservation. The epiphytes represent a functional group with high richness and abundance in neotropical forests, as well as presenting sensibility to environmental variations, thus representing a good model to study distribution patterns. The Atlantic Forest (AF) is one of the world biodiversity hotspots and is the Brazilian phytogeographic domain with the highest richness and endemism in epiphytes. Atlantic Domain has great elevation amplitude, mainly at the south portion, and the Serra da Mantiqueira (SM) is a mountain chain with the greatest elevations. In the SM, from 1200m, occur the cloud forest, characterized by constant fog and remarkable presence of epiphytes, and one of its subtypes, the dwarf cloud forests, are highly threatened by the global climatic changes. In order to know and understand the distribution patterns and richness of vascular epiphytes in different scales, the thesis was divided into three chapters. The Chapter 1 aimed to refine mapping of the distribution of richness and endemism of vascular epiphytes and to understand the abiotic factors responsible for the richness and species turnover in the Southern block of the Atlantic Forest (SBAF). We used datasets and generated two Generalized Dissimilarity Models (GDM). We found four regions presenting high richness and endemism and confirmed a gradient of richness and species turnover between coastal and inland areas, as well as between the lowland and highland forests. The main preditors from GDMs were geographical distance, cloud cover, and seasonality of temperature. The topographical heterogeneity and respective climatic changes are responsible for increasing the richness and species turnover of vascular epiphytes in SBAF. In Chapter 2 we aimed to list the vascular epiphyte species of cloud forests of the SM. We performed collections throughout the mountain chain and compiled a dataset. The cloud forests of SM presented 678 species, representing approximately 20% and 30% of the Brazilian and Atlantic Forest species, respectively. The 9 richest families, Orchidaceae, Bromeliaceae, and Polypodiaceae, confirmed the patterns obtained in different scales. Several threatened species in the national and state levels highlight the relevance of conservation of the remnants of the SM. In Chapter 3, we aimed to investigate the distribution of richness and composition of species throughout the elevation gradient in the cloud forests of the SM and to evaluate the influence of climatic and topographical variables. We established plots throughout different elevations of the SM to investigate the distribution at local and regional scales. The species richness was compared through rarefaction analysis and the composition was evaluated using analysis of similarity and correlation with environmental factors. We did not find intermediate peaks of richness at the local scale, but regionally the elevation interval between 1500m and 1700m presented the highest richness, especially if compared with the highest altitudes, where low temperatures represent an environmental filter, limiting the richness even with highest precipitation. Species composition is affected by climatic differences, throughout the SM, related to the seasonality, clustering plots of the same locality, despite the geographical distance did not represent a significant factor. The results presented here offer a starting point for observing the patterns of richness and composition of species in elevation gradients facing the global climatic changes.