Marcia Aguiar de Barros

Sugestões para padronização da metodologia empregada em estudos palinológicos do Quaternário

A metodologia detalhada a seguir foi definida pelos autores durante reunioes organizadas em Belo Horizonte por ocasiao do 3f? Congresso da Associacao Brasileira de Estudos do Quatemario (ABEQUA) em 1991. Consiste na padronizacao dos metodos de coleta e dos tratamentos fisico-quunicos a serem aplicados na preparacao das amostras destinadas a estudos em Palinologia. E recomendada para estudos palinologicos relacionados com o Quatemario e devera ser utilizada sempre que for possivel, com a finalidade de permitir uma comparacao entre os trabalhos dos diversos autores e a utilizacao dos dados publicados pela comunidade cientifica. Caso as condicoes de conservacao ou a natureza do material nao permitirem o uso desta metodologia, o autor devera descrever detalhadamente o seu procedimento.

Catálogo sistemático do pólen das plantas arbóreas do Brasil meridional. XXX: Meliaceae

Laboratorio de Palinologia, Departamento de Botânica, Instituto de Biologia, CCS, UFRJ, Cidade Universitaria,CEP 21949-900, Rio de Janeiro, RJ, BrasilCorrespondencia para: Ortrud Monika Barth, Instituto Oswaldo Cruz, Departamento de Virologia,Av. Brasil, 4365, CEP 21045-900, Rio de Janeiro, RJ, BrasilRecebido em 29/11/96 – Aceito em 02/06/98 – Distribuido em 28/08/98

Testing multivariate analysis in paleoenvironmental reconstructions using pollen records from Lagoa Salgada, NE Rio de Janeiro State, Brazil

Despite the indisputable significance of identification of modern analogs for Paleoecology research, relatively few studies attempted to integrate modern and fossil samples on paleoenvironmental reconstructions. In Palynology, this general pattern is not different from other fields of Paleoecology. This study demonstrates the practical application of modern pollen deposition data on paleoenvironmental reconstructions based on fossil pollen by using multivariate analysis. The main goal of this study was to use Detrended Correspondence Analysis (DCA) to compare pollen samples from two sediment cores collected at Lagoa Salgada, a coastal lagoon located at northeastern Rio de Janeiro State. Furthermore, modern surface samples were also statistically compared with samples from both cores, providing new paleoecological insights. DCA demonstrated that samples from both cores are more similar than previously expected, and that a strong pattern, related to a paleoenvironmental event, is present within the fossil data, clearly identifying in the scatter plot samples that represent pre- and post-environmental change. Additionally, it became apparent that modern vegetation and environmental conditions were established in this region 2500 years before present (BP). Multivariate Analysis allowed a more reliable integration of modern and fossil pollen data, proving to be a powerful tool in Paleoecology studies that should be employed more often on paleoclimate and paleoenvironmental reconstructions.

Evolução Paleogeográfica da Planície Costeira da Praia Vermelha, entrada da Baía de Guanabara, Rio de Janeiro, por meio de registros palinológicos

Peat sediments were observed during high tide occasions in the Praia Vermelha beach, urban area of the Rio de Janeiro city. They were studied to investigate possible environmental variations during the Quaternary Period. Palynological analysis was carried out comprising a time interval from ca. 4.520 A 80 to 4.270 A 60 years B.P. During this time the results obtained indicate that a restinga forest vegetation was sequentially dominated by a restinga bog vegetation. A great number of spores presenting corrosion/degradation damage, typical characteristics of exposition to the air, indicate that low quantity of water was disposable occasionally.

Archaeological Deposit in Motako, Southwest Nigeria, Investigated by Pollen Analysis

Pollen, in association with phosphate and archaeological data from a 120 cm deep midden deposit provide insight into site formation processes at Motako. Twelve samples were retrieved from the five distinct stratigraphic layers and subjected to pH and phosphate analyses, and pollen with some archaeobotanical analyses. Results showed that environmental factors influenced the oxidation of the deposit in addition to fungal activity, hence the low pollen content recorded. Five pollen zones were established according to the pollen, phosphate, lithological and archaeological data. The identified palynomorphs were dominated by fungal spores and Amaranthaceae pollen. Moreover, ruderals, including species of ethnobotanical relevance, and Elaeis guineensis pollen were identified, indicating open vegetation initiated possibly by human activity. Zone 1 (110–85 cm) was characterised by low phosphate content, coupled with archaeological materials, broken palm kernels, and low pollen diversity suggesting the area was likely used for activities related to palm oil production. At Zone II (85–70 cm), we suspected that the deposit had gradually been turned into a midden heap as indicated by increase in organic matter content which corresponded to the increased concentration of phosphate and cultural materials, in addition to the increase of pollen of ruderal species. In Zone III (70–45 cm) the midden deposit was fully established with high activity as reflected in the peak in phosphate content, increased diversity of kitchen wares, organic remains and pollen of ethnobotanical significance. The midden was probably beginning to be deactivated in Zone IV (45–25 cm) and/or used for another activity such as gardening for the cultivation of plants with several domestic purposes. Zone V (25–0 cm) shows a reduction of both organic and inorganic materials. The varying concentrations of archaeological material, phosphate and pollen content suggest changing site activities across the sedimentary units, depicting changes in land use and management over time for refuse disposal. The occurrence of decreasing concentration of organic waste towards the top of the sediment profile in tandem with phosphate concentration was considered to be an indicator of the gradual abandonment of the midden.

Palinologia, paleoflorística e aspectos paleoclimáticos de sedimentos do pleistoceno tardio na bacia hidrográfica do Rio Guandu, Rio de Janeiro, Brasil

For presenting great morphological diversity, pollen grains, especially from angiosperms, can be used to determine stratigraphic sequences, relate geographically separated regions and reconstitute the paleoenvironment. Since 1970s, palynological studies on quaternary sediments have been conducted in Brazil, registering vegetation changes and climatic variations that occurred through this geologic period. Palynological analyses on sediments from Guandu river hydrographic basin are presented aiming to reconstitute the previous vegetation, understand its evolution and infer the paleoclimate during the late Pleistocene. For decades, the area has been suffering deep physiognomic changes due to extractive activities, characterizes by the Piranema Sand District. The flood trenches, resulting from such mining activity, enabled the withdrawal of a muddy sedimentary package, containing organic matter, along a columnar profile on Santobaia Sand Pit. The deposit was divided into five levels and all submitted to the standard methodology in chemical treatment. Geochronological analysis appointed a time period between 42.500 and 35.200 A 340 years BP. Palynological data evidenced that, despite the cold and dry weather, distinctive of this glacial period, humidity level was sufficient for the establishment of a vegetation throughout the studied chronological interval. Locally, a flooded forest subjected to occasional fluvial overflows was present, as well as a dry lowland vegetation, in areas out of reach of floods. Palynomorphs indicating the formation of a permanently waterlogged site were not observed. Regionally, a hillside forest was inset with a low pollen record, but always present. These three plant formations coexisted during the considered time period, and the dimension of each one was directly influenced by the Guandu river basins hydrographic conditions.

Paleoambiente e Palinologia de um Nível de Sedimento de Cerca 40.000 Anos A.P. Retirado da Lagoa de Itaipu, Estado do Rio de Janeiro

The lake of Itaipu is located in the central coastal plain, northern to the city of Rio de Janeiro. It started during the late Pleistocene upon an elder swampy underground. During its aging into the Holocene period, the vegetation changed between the domains of forests, savannas and hydrophytes. A 160 cm long sediment core was obtained and a sample was selected at the basis of the core for pollen analysis, dated of 38,490 A 940 non-calibrated years B.P.. Pollen analysis identified 32 pollen types leading to characterize four types of vegetation: the rain forest vegetation, the forest pioneer vegetation, the herbaceous swamp vegetation and the field vegetation. Pollen grain frequency and concentration showed that at this time the area was covered with a mosaic of plant communities, that the lake was not yet installed, and that a humid environment provided the maintenance of high plant diversity.

Tafonomia de Esporos de Pteridófitas Encontrados em Sedimentos Turfosos Quaternários do Rio de Janeiro, Brasil

Taphonomy is a tool used in palaeoenvironmental interpretations dating back to the process of palynomorphs deposition. The interpretation of taphonomic studies provides subsidies to the understanding of the environmental past conditions through the marks left on the preserved palynomorphs. The study area is located in the Praia Vermelha, Urca district, municipality of Rio de Janeiro, in the entrance of Guanabara Bay. The preservation of spores inside a columnar profile, constituted of peat and sandy mud sediments, was studied, comprising a time interval from about 4,520 to 4,270 years B.P. Eight levels were selected and sampled. The spores were classified according to the type of deterioration, by damages of corrosion and degradation and by mechanical damages. The percentage of each kind of deterioration was calculated in relation to the total number of counted spores and the concentration in relation to one cm³ of sediment. A large number of spores presenting corrosion and degradation damages was observed, being characteristic of air exposure, indicating occasions of lower water availability in this site. The predominance of undamaged spores in some levels suggests an underwater sedimentation, corroborated by sedimentary analyses.