Andreia Cardoso Pacheco Evaldt

Grãos de pólen e esporos do Vale do Rio Caí, nordeste do Rio Grande do Sul, Brasil: descrições morfológicas e implicações paleoecológicas

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.

Pollen morphology of Brazilian Fevillea (Cucurbitaceae)

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.

Late Holocene Vegetation History and Early Evidence of Araucaria angustifolia in Caçapava do Sul in the Lowland Region of Rio Grande do Sul State, Southern Brazil

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.

Pollen and spores atlas of the Caí River Valley, RS, Brazil.

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.