Soraia Girardi Bauermann
Universidade Luterana do Brasil
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Featured researches published by Soraia Girardi Bauermann.
Palaeogeography, Palaeoclimatology, Palaeoecology | 2004
Hermann Behling; Valério D. Pillar; László Orlóci; Soraia Girardi Bauermann
Abstract Late Quaternary vegetation, fire and climate dynamics have been studied based on high-resolution dated pollen and charcoal samples and multivariate data analysis. The samples were taken from a 212-cm-long sediment core of a bog in the Cambara do Sul region on the highlands of northeastern Rio Grande do Sul State, Brazil. The records, including seven AMS radiocarbon dates, span 42 840 14C years, for the first time extending the reconstruction of past environmental changes on the southern Brazilian highlands back to the Last Glacial Maximum (LGM) and pre-LGM times. The last 1100 years provide a decadal resolution. Initially the site was a permanent shallow lake which became seasonally dry after 26 900 14C yr BP. Seasonal climate with a long annual dry period prevailed until the late Holocene. The climate was somewhat wetter from 42 840 to 41 470 14C yr BP and from 41 470 to 26 900 14C yr BP than during the LGM and the late-Glacial period. Natural fires were rare, but became very frequent after 7400 cal BP, suggesting human occupation of the southernmost Brazilian highlands since that time. The records suggest that a species-rich Campos (grassland) vegetation existed in the area under a relatively dry and cold climate during glacial times under possibly as low as −10°C. The record also suggests that small populations of Araucaria were probably only present in refugia of deep and protected valleys and/or on wetter coastal slopes. Campos vegetation existed through the early and mid-Holocene until 4320 cal yr BP, after which Araucaria forest expanded into the network of gallery forests along the streams. By 1100 cal yr BP the Araucaria forest replaced the Campos vegetation reflecting the onset of the wettest period with no marked annual dry season. The marked expansion of the Araucaria forest coincided with the reduction in fire. Between AD 1520 and 1770 Weinmannia became a common taxa in the Araucaria forest, suggesting a shift to warmer climatic conditions on the highlands. This interval was synchronous with a cool phase within the Little Ice Age known from North Atlantic land records. After about AD 1780 human activities changed the original forest composition, first by introducing cattle into the forest and than by selective logging of Araucaria trees. Multivariate analysis of the pollen data shows compositional changes that follow a trajectory alternating undirectional, random phases and phases with directional, sometimes fast transitions. The results also show that compositional changes in the vegetation are slower during cool periods (LGM compared to pre-LGM) and faster in warm periods (Holocene).
Gaea - Journal of Geoscience | 2007
Renato Backes Macedo; Rodrigo Rodrigues Cancelli; Soraia Girardi Bauermann; Sérgio Augusto de Loreto Bordignon; Paulo César Pereira das Neves
Este trabalho apresenta os resultados da analise palinologica de 51 amostras obtidas em um testemunho de sondagem de 270 cm de espessura, realizado na localidade de Passinhos, municipio de Osorio, Planicie Costeira do Rio Grande do Sul, Brasil. Ao longo do perfil foram selecionadas tres amostras para datacao com 14C e a mais basal forneceu uma idade de 10.600±90 anos A.P. Foram identificados 71 palinomorfos, agrupados conforme seus respectivos habitos e/ou habitats e tratados estatisticamente de modo a fornecer diagramas polinicos de porcentagem e concentracao. As quatro zonas palinologicas identificadas evidenciam a gradativa colmatacao de um lago e as mudancas vegetacionais dai decorrentes e, finalmente, os efeitos da colonizacao humana. Permitiram, ainda, sua correlacao com dados anteriores, obtidos em outras areas da Planicie Costeira. Palavras-chave: Palinologia, Holoceno, Rio Grande do Sul, Brasil.
Anais Da Academia Brasileira De Ciencias | 2010
Renato Backes Macedo; Paulo Alves de Souza; Soraia Girardi Bauermann; Sérgio Augusto de Loreto Bordignon
A sedimentar core collected at Santo Antônio da Patrulha, Rio Grande do Sul State, southmost Brazil, was submitted to pollen analysis to provide the vegetational history of this region, and the paleoecological and paleoclimatic changes. A total of 98 taxa of palynomorphs was identified from 35 subsamples. Three radiocarbonic datings were obtained along a section of 115 cm depth, including the basal age of 4730 ± 50 yr BP. Pollen diagrams and cluster analysis were performed based on palynomorphs frequencies, demonstrating five distinct phases (SAP-I to SAP-V), which reflected different paleoecological conditions. The predominance of plants associated with grasslands in the phase SAP-I suggests warm and dry climate conditions. A gradual increasing of humidity conditions was observed mainly from the beginning of the phase SAP-III, when the vegetation set a mosaic of grasslands and Atlantic rainforest. Furthermore, the presence of some forest taxa ( Acacia-type, Daphnopsis racemosa, Erythrina-type and Parapiptadenia rigida-type), from the phase SAP-IV, is interpreted as an influence of the seasonal semideciduous forest in the study region. From the phase SAP-V (ca. 4000 yrs BP), the vegetation became similar to the modern one (extant Atlantic rainforest Biome), especially after 2000 yrs BP (calibrated age).
Palynology | 2016
Izabella Martins da Costa Rodrigues; Bruno Fernandes Falcão; João Renato Stehmanna; Soraia Girardi Bauermann
Aureliana and Athenaea (Withaniinae, Solanaceae) are two genera of shrubs or small trees with centres of diversity in the Brazilian Atlantic Rain Forest. They are difficult to distinguish using gross morphology, and are traditionally segregated based on differences in fruiting calyx size. Pollen grains of all taxa were acetolysed, treated and examined with light and scanning electron microscopy, with the aim of identifying diagnostic characters. Microphotographs and illustrations of pollen grains are presented. The species analysed present small- to medium-sized monad pollen grains of varying morphology with long to extremely long colpi, and lalongate endoapertures. The analysis showed that the pollen grains of both genera are very similar, differing in size-related characters. These data contributed to the synonymisation of Athenaea within Aureliana.
Frontiers in Plant Science | 2016
Jefferson Nunes Radaeski; Soraia Girardi Bauermann; Antonio Batista Pereira
This aim of this study was to distinguish grasslands from forests in southern Brazil by analyzing Poaceae pollen grains. Through light microscopy analysis, we measured the size of the pollen grain, pore, and annulus from 68 species of Rio Grande do Sul. Measurements were recorded of 10 forest species and 58 grassland species, representing all tribes of the Poaceae in Rio Grande do Sul. We measured the polar, equatorial, pore, and annulus diameter. Results of statistical tests showed that arboreous forest species have larger pollen grain sizes than grassland and herbaceous forest species, and in particular there are strongly significant differences between arboreous and grassland species. Discriminant analysis identified three distinct groups representing each vegetation type. Through the pollen measurements we established three pollen types: larger grains (>46 μm), from the Bambuseae pollen type, medium-sized grains (46–22 μm), from herbaceous pollen type, and small grains (<22 μm), from grassland pollen type. The results of our compiled Poaceae pollen dataset may be applied to the fossil pollen of Quaternary sediments.
Gaea - Journal of Geoscience | 2009
Andreia Cardoso Pacheco Evaldt; Soraia Girardi Bauermann; Sabrina Castelo Branco Fuchs; Suzete Diesel; Rodrigo Rodrigues Cancelli
A analise de formas atuais de graos de polen e esporos e sua posterior organizacao em uma colecao de referencia foram realizadas com as especies mais comuns de plantas do Vale do Rio Cai, sul do Brasil. Este procedimento objetiva o conhecimento dos aspectos morfologicos desses materiais, para facilitar as comparacoes com graos dispersos em sedimentos do final do Cenozoico e propiciar reconstituicoes paleoecologicas e paleoclimaticas. Os graos de polen foram selecionados entre os que melhor representam as distintas formacoes vegetacionais presentes, Floresta Ombrofila Mista, Floresta Estacional Decidual, Floresta Estacional Semidecidual e Estepe (Campos) e receberam tratamento previo com o metodo de acetolise. Sao apresentadas as medidas, a descricao e a ilustracao das 93 formas identificadas, das quais 63 sao ineditas para o Estado do Rio Grande do Sul, atestando a carencia de dados e estudos polinicos regionais. Palavras-chave: polen, esporos, Quaternario, Vale do Rio Cai, sul do Brasil.
Grana | 2010
Luís F. P. Lima; Andreia Cardoso Pacheco Evaldt; Soraia Girardi Bauermann; Silvia Teresinha Sfoggia Miotto
Abstract Pollen morphology of the five Brazilian species of the genus Fevillea (F. bahiensis, F. cordifolia, F. passiflora, F. pedatifolia, and F. trilobata) was studied using light and scanning electron microscopy. Pollen in these species is generally stenopalynous, which is in agreement with observations in previous studies of other species. Pollen is shed in monads and characterised by being isopolar, radially symmetric, prolate, and striate. Pollen is of medium size, tricolporate, with long and narrow colpi, a circular endoaperture and a reduced polar area. The exine is up to 2 μm thick.
Brazilian Archives of Biology and Technology | 2016
Hermann Behling; Nuno Verissimo; Soraia Girardi Bauermann; Sérgio Augusto de Loreto Bordignon; Andreia Cardoso Pacheco Evaldt
Little is known about the southernmost occurrence of small areas with Araucaria angustifolia populations in Cacapava do Sul in low elevated areas of Rio Grande do Sul State, about 130 km to the south of to the highlands of southern Brazil where the main distribution of Araucaria is found. This occurrence is about 130 km further south to the main area of Araucaria angustifolia which is on the highlands in southern Brazil. The question is whether this occurrence is natural, due to indigenous peoples, or due to plantation by post-Columbian settlers. To trace the origin of this little known southernmost existence of Araucaria angustifolia trees is of particular interest for conservation issues. To address this question we did a vegetation survey and studied a 150 cm-long radiocarbon dated sediment core from the Fazenda da Monica by pollen analysis. The vegetation survey of the study area indicates that also other typical taxa of the Araucaria forest as well as the Atlantic lowland rainforest are found in the present-day semi-deciduous forest, such as Podocarpus, Ilex, Myrsine and Prunus for the former, and Alchornea, Moraceae, Arecaceae, and Myrtaceae for the later. The pollen record, due to bad pollen preservation, starts only after 44 cm core depth, which is about 515 cal yr BP old (AD 1490), indicating that Araucaria angustifolia as well as other Araucaria forest and Atlantic rainforest taxa occurred in this area since the beginning of the pollen record. The occurrence of these taxa can be seen as natural and not introduced during the post-Columbian colonisation. First settlers at the beginning of the 19th century reduced existing population of Araucaria markedly and in particular since about AD 1950. The population of Araucaria angustilfolia before the post-Columbian settlement was much larger than today.
Revista Arvore | 2009
Soraia Girardi Bauermann; Andreia Cardoso Pacheco Evaldt; Sabrina Castelo Branco
A descriptive atlas of pollen and spores from plants of Cai river Valley aimed to facilitate the identification of dispersed palynomorphs in fossil sediments and provide data for environmental management actions. The atlas presents 93 characteristic species of four Cai river valley plant associations, including Floresta Ombrofila Mista, Floresta Estacional Decidual, Floresta Estacional Semidecidual and Estepe, besides exotic plants and disturbed sites. In this first part, detailed descriptions and light micrographs of 24 species, 21 genera, and 17 families were included.
Review of Palaeobotany and Palynology | 2005
Hermann Behling; Valério D. Pillar; Soraia Girardi Bauermann