Padrões de habitats das espécies de begonia (Begoniaceae) na reserva ecológica de Guapiaçu, Cachoeiras de Macacu, RJ, Brasil

Abstract

The family Begoniaceae is pantropical and includes about 1400 species. In Brazil, it is represented only by the genus Begonia, with 208 species and the Atlantic Rain Forest as its center of diversity. To know the environments where the species occur and the factors that influence the dispersal and establishment of these species is of fundamental importance for their conservation. The aim of this work is to characterize the habitat of species of the genus Begonia in environments of continuous forest and in forest fragments of the Ecological Reserve Guapiaçu (REGUA), localized in the Municipality of Cachoeiras de Macacu, Rio de Janeiro, Brazil (22° 25' 45" S – 42° 44' 62" W). The research attempted to answer the following questions: (a) what are the abiotic characteristics of the habitats of Begonia species in REGUA? (b) what are the preferred environments of Begonia species in REGUA? and (c) are there differences in richness, abundance and abiotic conditions of Begonia habitats among fragments of different sizes and between the fragments and continuous forest? Data were collected on biotic and abiotic characteristics of environments where populations of Begonia spp. occur, such as, size and area of the populations, habits and life forms of the species, canopy opening, altitude, slope, distance to water source, distance to the edge of the fragment, sun exposure, height of the O-horizon, depth of leaf litter and presence of any relevant floristic or physical elements. Altogether, 17 species of Begonia were found in 105 populations: B. arborescens Raddi, B. bidentata Raddi, B. convolvulacea A.DC., B. cucullata Willd, B. dentatiloba A. DC., B. fruticosa A.DC., B. hirtella Link., B. hispida Schott, B. hookeriana Gardner, B. integerrima Spreng, B. lunaris E.L.JACQUES, B. pulchella Raddi, B. ramentacea Paxton, B. solananthera A.DC., B. sylvestris A.DC., Begonia sp.1 and Begonia sp.2. The shrub life form was predominant, representing 65% of samples. The herbs accounted for 12% of all species. Terrestrial was the predominant habit, with 58% of the species. The species with the largest populations in the study area, equally in continuous forest as in fragments, were B. sylvestris, B. hookeriana and B. hirtella with 18, 17 and 16 populations, respectively. Populations of B. hookeriana and B. sylvestris showed the largest variations in the number of individuals, populations ranging from about ten to over 200 individuals, whereas B. cucullata, B. integerrima, B. lunaris and B. pulchella did not exceed ten individuals per population. The species B. hirtella, B. hookeriana, B. integerrima and B. sylvestris showed the largest areas of occupation and also the largest variation of this parameter, with areas ranging from less than 1m2 to over 100m2. Species which had the highest importance values were B. sylvestris, B. hookeriana and B. hirtella. The abiotic parameters measured showed great variation, allowing trends to be observed in preference of some species for specific environmental conditions. However, new research is necessary that will complement the results obtained here and allow for the determination of indicator species of environmental quality.