Samambaias e Licófitas: florística e aspectos biogeográficos na Floresta Atlântica no Nordeste do Brasil

Abstract

The ferns and lycophytes comprise the seedless vascular plants and present the dominant sporophytic phase. They are currently distributed in several regions, with a greater predominance in the Tropical region, occurring mainly in the humid forests, such as the Atlantic and Amazonian Forest, with 915 and 534 species recorded respectively in Brazil. This work aims to record the occurrence of fern and lycophyte species in remnants of the Atlantic Forest in the states of Rio Grande do Norte and Ceará, for the conservation of biodiversity and important for the formation of corridors in the Atlantic Forest. Through the distribution of the species of the family Pteridaceae an analysis of panbiogeography was developed aiming to find generalized tracks compatible with the routes for species exchange between the Atlantic and Amazonian Forest. Considering that these routes would be viable for the presence of forest fragments in other phytogeographic domains such as the Caatinga, Cerrado and Pantanal, a biome distribution model was generated in South America in order to establish the biome delimitation during the Last Glacial Maximum (glacial period) and during the Mid Holocene (interglacial period). The registration of ferns and lycophytes occurred in three conservation units, the Ubajara National Park, the Environmental Protection Area (EPA) Serra da Meruoca (both in Ceará) and the Relevant Ecological Interest Area (REIA) Mata da Bica (Rio Grande do Norte). In these areas, the greatest number of environments possible were visited, mainly those with the highest occurrence of ferns and lycophytes, the material collected was herborized and deposited in the RN, UFRN, EAC and JPB herbarium. For the analysis of panbiogeography, a spreadsheet with the record of Pteridaceae species occurring in the Northern Atlantic Forest was elaborated then individual tracks, generalized and panbiogeographic nodes were elaborated by means of the Martitracks and Quantum Gis softwares. For the modeling of the biomes distribution during the glacial and interglacial period, the Maxent software was used, with the algorithm of the same name and the Openmodeller software with the environmental distance algorithm, was used. The flora recorded in the REIA Mata da Bica and EPA Serra da Meruoca corresponds to 17 species of ferns and one lycophyte. According to the similarity analysis, a greater floristic similarity was observed between the EPA Serra da Meruoca and REIA Mata da Bica with areas of the Caatinga phytogeographic domain, even occurring in the Atlantic Forest phytophysiognomy. Through the analysis of Panbigeography it was identified that the spatial homologies found through generalized tracks, corroborate with the main routes for the interchange of species between the Atlantic and Amazonian Forests. In relation to the delimitation of the biomes during the glacial and interglacial periods, it was observed that most areas of the analyzed biomes showed expansion during the Mid Holocene in comparison with the Last Glacial Maximum. Expansion occurred in the Tropical and Subtropical Moist Broadleaf Forests (19.52%), Grasslands, Savannas and Temperate Shrublands (12.12%), and Tropical and Subtropical Dry Broadleaf Forests (8.76%). There was retraction in the Flooded Grasslands and Savannas (1.25%) and Tropical & Subtropical Grasslands, Savannas & Shrublands (6.38%). Areas of stability of wet forests that could act as bridges for species exchange were also recorded.