Late Quaternary vegetation and climate dynamics in the Serra da Bocaina, southeastern Brazil

Late Quaternary vegetation, fire and climate dynamics were studied by pollen and charcoal analysis in the Serra da Bocaina, in the coastal ranges of southeastern Brazil, Rio de Janeiro and São Paulo States. Samples were taken from two cores, Serra da Bocaina 1 and 2. Seven radiocarbon dates indicate deposits of Late Pleistocene to Holocene age. During the period between 18,570 and 14,570 cal BP wide-spread grassland (“campos”) with frequent fires existed in the higher Serra da Bocaina; taken together with other evidence, this indicates relatively dry and cold climatic conditions for this period. Upper montane forest occurred in protected valleys or on slopes at lower elevations. The conifer Araucaria angustifolia has been present in the Serra da Bocaina since the Late Pleistocene, but populations have fluctuated. An erosion hiatus in the Late-glacial period, evidenced by reworked deposits lacking pollen, was probably caused by increased rainfall during the Younger Dryas period. Upper montane forest taxa expanded during the Holocene, especially after 7260 cal BP. Indications are that the early and mid Holocene were dry and relatively warm, with an annual dry season longer than present day. Modern patches of campos in the Serra da Bocaina are remnants of more expansive grasslands during glacial times.