Padrões florísticos e ecológicos de epífitas vasculares em áreas prioritárias para a conservação na floresta Atlântica Brasileira

Abstract

Despite the intense process of degradation, the Atlantic Forest houses biological megadiversity and high endemism indices and is considered one of the main world hotspots of biodiversity. However, even with the concentration of Brazilian researches in the Atlantic domain, the knowledge about the floristic composition is not evenly distributed, and several gaps must be fulfilled, as in the case of Seasonal Semi-deciduous Forests (SSF). For example, some studies indicate the priority areas for conservation of the Brazilian diversity, but several localities do not have sufficient studies, difficulting the elaboration of conservation strategies. Many of those areas are located in the Minas Gerais (MG) state, lying in the mountainous complex of Serra da Mantiqueira (SM), whose biotic and abiotic relevance are notorious. Both areas and functional groups are undersampled, as in the case of vascular epiphytes, which are important for the ecological dynamics of tropical forests but are poorly known if compared with tree plants. Thus, the present study aimed to investigate priority areas for the conservation of the flora of MG inside the Atlantic Forest, composed of SSF phytophysiognomy. We performed floristic surveys, evaluation of the community structure, and analyses of patterns of the geographical distribution of vascular epiphytes. Three chapters compose this thesis. In the first chapter, we discussed the necessity of continuity of floristic surveys, mainly for non-tree species, even in relatively well-sampled areas like the SM, which is unevenly studied e has several gaps of sampling and knowledge. We present for the first time the records of occurrence of three species in MG, the rediscovery of one species after two centuries from its last collection, and some species rarely collected in the state. These results highlight the importance of efforts in sites with a deficit of knowledge and suggest the region of Itamarati de Minas as a priority area for the conservation of biodiversity in MG, once the majority of records come from the aforementioned municipality. The second chapter presents the checklist of vascular epiphytes of the Serra do Relógio, recording 158 species. 12 This richness is surprisingly higher than found in some rainforests, which are more prone to the occurrence of this synusia, due to high moisture levels and low seasonality. We also analyzed the floristic similarity between two forest remnants in different elevations (~500m and 1400m). Despite the connection through an ecological corridor and the same phytophysiognomy, the similarity found was very low (~22%), showing that local environmental features can strongly influence the composition of vascular epiphytes communities. These data reinforce a trend of a high richness of vascular epiphytes in the SSF of Minas Gerais and the importance of conservation of every remnant of vegetation in Brazil. In the third chapter, we analyzed the distribution of vascular epiphytes in 12 sites composed by SSF in the Serra da Mantiqueira with latitudes varying between 20°24' and 21°41' and altitudes between 250m and 1650m. We evaluated richness, diversity taxonomic indices, floristic similarities between the areas (through clustering and ordination methods), and the β diversity partitioned in two components (nestedness and turnover). The found richness pattern partially proves the hypothesis, with the three richest sites lying between 1000m and 1500m. However, this pattern has not been maintained when considering all areas. In general, high indices of taxonomic diversity showed that the localities are reasonably conserved. The similarity analyses highlight altitude as a determinant feature in the distribution of the táxons, forming two groups above and below the 1000m. The levation is also important in the β diversity analysis, where the component turnover was the main factor of dissimilarity, showing there is an additive differentiation of species among the studied communites. Even the sites with low richness were not subsets of the richest, justifying to include this type of remnant in conservation initiatives. Our results contributed to fulfilling some gaps of knowledge in the SSF of Serra da Mantiqueira, bringing an updated listing of this synusia to this phytophysiognomy, new data about richness, community structure, and distribution of 13 vascular epiphyte species in areas with high relevance for the conservation of Brazilian diversity.