Ecologia e similaridade de Orchidaceae em um trecho da Serra da Mantiqueira na Zona da Mata de Minas Gerais, Brasil

Abstract

The presente work aims to present a species list of Orchidaceae associated to an assessment of distributional patterns along an altitudinal gradient and a correlation with habitats mosaics at SerraNegra/Serra do Funil (SN/SF). The present study also aimed to investigate the floristic similarities of Orchidaceae from SerraNegra/Serra do Funil (Rio Preto County, Minas Gerais State, Brazil) with 29 floras from sites in Southeastern Brazil, Distrito Federal, Bahia, Paraná, and Rio Grande do Sul States. Those mountains are located in Southern Mantiqueira Range, at Minas Gerais State, an very interesting biological site. Field work consisted on seven expedition. Collections are deposited at CESJ. The altitudinal gradient was divided in classes of 100m. The phytophysiognomies were defined informally, as underforest, Field, transitional área and degraded área. Habitat and elevation data were obtained in situ or taken from plant labels. The associations between preferred substrate and altitudinal classes were tested by Chi-Square test. The cluster analyses used UPGMA algorithm based on Sorensen coefficient. The clusters’ support was tested by bootstrap analyses with 5000 replications. The Mantel Test was applied to evaluate the relation between the floristic similarity and the geographical distance. There were registered 109 species of Orchidaceae. The epifitic species represent 51% of the richness. The species are distributed in the interior of the forests and also along the open fields. Most of them were exclusive of those habitats. The altidutinal classes with highest richness (900-1000m, 1301-1400m e 1501-1600m) were the most preserved areas at the study site and their environmental and phytophysionomic heterogeneity should justify that richness. The Chi-Square Test showed no association between life forms (terrestrial and epifitic) and altitudinal classes. The result of the cluster analyses was statistically significant, and were found low similarity indices, exceptions are the clusters composed by Serra Negra/Serra do Funil + Parque Estadual do Ibitipoca and Parque Estadual da Ilha do Cardoso+Estação Ecológica Juréia-Itatins. The most relevant result was that clusters grouped sites environmental similar. The studied area (SN/SF) showed to be more related to other sites of open rocky grasslands under the influence of the Atlantic Forest. The SN/SF also showed similarity with Parque Nacional do Itatiaia and Reserva Biológica de Macaé de Cima, sharing approximately 56% of the Orchidaceae species, they are suggesting that SN/SF should be considered a floristic corridor between sites in Serra da Mantiqueira. The sites open rocky grasslands were highlight due their special floristics features. The Mantel test revealed no association between the floristic similarity and the geographical distance of the areas. The

questions remain opened in relation to what factors are influencing the diversity and the distributional patterns of Orchidaceae, then other ordination tests ordination, including abundancy and environmental data should be applied.